Drilling Machine

  • The Drilling Machine is one of the most significant machine apparatuses in a workshop.
  • In Drilling machine holes may be drilled quickly and at lower cost.
  • The hole is produced by the turning edge of a cutting apparatus known as the drill which applies huge power on the work clipped on the table.
  • Holes were drilled by the Egyptians in 1200 B. C. about 300 years ago by bow drills.
  • The bow drill is the mother of present day metal cutting Penetrating machine.

Definition of Drilling Machine

  • Drilling machine is a machine which makes a circular hole in the workpiece by removing metals in the form of chips with the help of a cutting tool called Drill Bit.

Types of Drilling Machine

  • The various kinds of Drilling machines are as per the following :

1. Portable Drill machine 

2. Upright Drill machine

3. Gang Drill machine

4. Automatic Drill machine

5. Sensitive Drill machine

6. Radial Drill machine

7. Multi Drill machine

8. Deep hole Drill machine

1. Portable Drill machine 

  • This sort of Drill machine can be works easily anyplace in the workshop for boring gaps in workpieces in any position which can’t be bored in a standard Drilling machine.
  • The engine is for the most part of all inclusive kind which might be driven by both A.C and D.C.
  • The maximum size of the drill that it can accommodate is not more than 12 – 18 mm.
  • The machine operates at high speed as smaller size drills are only used.

2. Upright Drill machine

  • It designed for handling medium size workpieces.
  • An enormous number of axle speeds and feeds might be accessible for penetrating various kinds of work.

Upright_Drilling_Machine

Image : Upright Drilling Machine

  • The table of the machine additionally have various kinds of alterations.
  • There are two general classes of it :-

i. Round column section or Pillar Drill machine

  • It consists of a round column that rises from the base which rests on the floor, an arm and a round table assembly, and a drill head assembly.
  • The table and the arm might be moves in a circular segment upto 180° around the section and might be clipped at any position.
  • The table may be rotates 360° about its own centre independent of the position of the arm for locating workpieces under the spindle.
  • The maximum size of holes that the machine can bore isn’t in excess of 50 mm.

ii. Box column section Drill machine

  • It has the square table fitted on the slides at the front face of the machine column.
  • Heavy box column gives the machine strength and unbending nature.
  • The table is raised or brought down by a hoisting screw that gives extra help to the table.
  • These unique highlights license the machine to work with heavier workpieces, and gaps in excess of 50 mm in distance across.

3. Gang Drill machine

  • It is a machine where various single axle drill machine segment are put next to each other on a typical base and have a typical worktable
  • It has four to six spindles may be side by side.
  • A series of operations may be performed on the work by spindle shifting the work from one position to the other on the work table.
  • The speed  and feed of the spindles are control independently.

4. Automatic Drill machine

  • It can play out a progression of machining tasks at progressive units and move the work from one unit to the next naturally.
  • This kind of machine is planned only for generation purposes might be utilized for processing, Honing and comparative activities notwithstanding boring and tapping.

5. Sensitive Drill machine

  • This is a small machine design for drilling a small holes at high speed in light jobs.
  • The base of the machine may mount on a bench or on the floor.

Drilling Machine | Definition, Types, Parts, Operation & Tools

Image : Sensitive Drill machine

  • It comprises of a vertical section, a level table, a head supporting the engine and driving instrument, and a vertical shaft for driving and turning the drill.
  • There is no course of action for any programmed feed of the drill shaft.
  • Its capable of rotating drills of diameter from 1.5 – 15.5 mm.

6. Radial Drill machine

  • It intended for drilling medium to large and heavy workpieces.
  • It comprises of a substantial, round, vertical section mounted on an enormous base.
  • The segment bolsters an outspread arm which can be raised and brought down to suit workpieces of various stature.

7. Multi Drill machine

  • Its main function is to drill a number of holes in a piece of work.

Drilling Machine | Definition, Types, Parts, Operation & Tools

Image : Multiple Spindle Drilling Machine

  • Also to reproduce the same pattern of holes in a number of identical pieces in a mass production work.

8. Deep hole Drill machine

  • In this machine, special machines and drills are use for drilling deep holes in rifle barrels, crank shafts, long shafts, etc.
  • A long activity is typically bolstered at a few focuses to forestall any redirection.
  • The machine may be horizontal or vertical type.

Also Read 

Lathe machine- Introduction, Parts, Operation, Working Principle.

Milling machine – Definition, Types, Parts, Operation.

Capstan Lathe & Turret lathe 

Parts of Drilling Machine

  • It has following major parts :

Drilling Machine | Definition, Types, Parts, Operation & Tools

 

1. Head

2. Spindle

3. Drill chuck

4. Table

5. Base

6. Column

 

1. Head

  • It is mounted on the highest point of the segment and houses the driving and encouraging component for the axle.

2. Spindle

  • This is taper shaft in circular shape which helps to hold the drill chuck.
  • Its made up of high carbon chromium steel, stainless steel or steel alloys.
  • They transfer the rotary motion from drill head to drill jigs.
  • It can move up and down with the help of rack and pinion mechanism.

3. Drill chuck

  • It is generally self – centering which is made of special alloy steel.
  • Its present on the lower end of the spindle.

4. Table

  • Its present on the column with T -slots for clamping the work directly on its face.
  • They may be round or rectangular in shape.

5. Base

  • It is that part of a machine on which vertical column is present.
  • Its support the column and worktable with other attachments.
  • It made up of casting.

6. Column

  • It is the vertical member of the machine that supports the table and the head containing all the driving mechanism.
  • It may be made of box section or of round section.
  • Box column is more rigid unit.
  • In Box column type, the front face of the column is accurately machine to form guideways on which the table can slide up and down for vertical adjustment.
  • In the round segment rack teeth are cut on the essence of the segment for vertical development of the arm and the table.

Operation of Drilling Machine

  • The various operations that can be performed in a drilling machine are :

1. Drilling

2. Boring

3. Reaming

4. Counter Boring

5. Counter Sinking

6. Spot Facing

7. Tapping

8. Lapping

9. Grinding

10. Trepanning

 Drilling Machine | Definition, Types, Parts, Operation & Tools

Image : Operation of Drilling Machine

1. Drilling

  • Drilling is an operation of producing a cylindrical hole by removing metal by rotating edge of cutting tool call as Drill.

Drilling Operation

Image : Drilling Operation

  • This is one of the simplest methods of producing a hole.
  • It doesn’t produce an accurate hole in a workpiece due to the vibration of the spindle and drill.

2. Boring

  • The purpose of boring is to enlarge a hole by means of an adjustable cutting tool with only one cutting edge.
  • It machine the internal surface of a hole already produced in casting.
  • To correct out of roundness of the hole.
  • To address the area of the gap as the drilling apparatus follows an autonomous way as for the gap.

3. Reaming

  • It is a precise method for estimating and completing an opening which has been recently bored.
  • The tool uses for reaming is known as the reamer which has multiple cutting edges.
  • It can’t originate a hole.

Reaming

 

  • It basically follows the way which has been recently bored and expels an extremely limited quantity of metal.
  • The material removes through this process is around 0.375 mm and for accurate work this should not exceed 0.125 mm.

4. Counter Boring

  • This is an operation of enlarging the end of a hole cylindrically.

Counter_Boring

 

  • The enlarged hole forms a square shoulder with the first gap.
  • The cutting speed for this operation is 25 % less than that of drilling.

5. Counter Sinking

  • It is an activity of making a cone – shaped enlargement of the end of a hole to provide a recess for a flat head screw or countersunk rivet fitted into the hole.

Countersinking

 

  • The standard countersinks have 60°, 82° or 90° included angle and the cutting edges of the tool are formed at the conical surface.

6. Spot Facing

  • This is an operation of smoothing and squaring the surface around a hole for the seat for a nut or the head of a screw.

Spot_Facing

 

  • A counter bore or an extraordinary spot confronting apparatus might be utilized for this reason.

7. Tapping

  • This is an operation of cutting internal threads by means of cutting tool called a tap.
  • A tap might be considered as a jolt with precise strings cut on it.

Tapping

 

  • The threads act as cutting edges which are solidified and ground.
  • It removes metal and cuts internal threads which will fit into outer threads of the same size.

8. Lapping

  • This is an operation of sizing and finishing a small diameter hole already hardened by removing a very small amount of material by using a lap.
  • The lap fits in the hole and moves up and down while it revolves.

9. Grinding

  • It is an operation to finish a hardened hole.
  • The grinding wheel is made to rotate with the shaft and is exhausted and down.
  • The accuracy in grinding operation is quite high about ± 0.1125 mm.

10. Trepanning

  • This is an operation of producing a hole by removing metal along the circumference of a hollow cutting tool.
  • It performs for producing large holes.

Trepannings

 

  • The tool resembles a hollow tube having cutting edges at one end and a strong shank at the other to fit into the drill spindle.
  • This is one of the effective strategies for delivering a hole.

Drilling Machine tools

1. Drill

  • A Drill is a fluted cutting tool used to originate or enlarge a hole in a strong material.
  • It manufactures in a wide variety of types and sizes.
  • The types of the drill commonly use :

i. Flat or Spade Drill

ii. Straight Fluted Drill

iii. Two Lip Twist Drill

iv. Taper Shank Core Drill

v. Oil Tube Drill

vi. Centre Drill

i. Flat or Spade Drill

  • A flat drill is sometimes used when an equivalent sized twist drill is not available.
  • It is usually made from a piece of round tool steel which is forge to shape and ground to size.
  • The cutting edge differs from 90° – 120° and alleviation or leeway at the forefront is 3° – 8°.

Disadvantages

  • This types of drill is that each time the drill is ground the diameter is reduced.
  • It can’t be relief upon to drill a true straight hole, since the point of the drill has a tendency to run out of the centre.
  • The chips don’t come out from the hole automatically, but tends to pack more or less tightly.

ii. Straight Fluted Drill

  • It has grooves or flutes running corresponding to the drill axis.
  • This may be consider as a cutting tool having zero rake.

Straight_Fluted_Drill

Image : Straight Fluted Drill

  • Its inconvenient in standard practice as the chips don’t come out from the hole automatically.
  • Its mainly use in drilling Brass, Copper, or other softer materials.

iii. Two Lip Twist Drill

  • It was initially made by twisting a flat piece of tool steel longitudinally for several revolutions, then grinding the diameter and the point.
  • The present day twist drills are made by machining two spiral flutes or grooves that run longwise around the body of the drill.
  • Twist drill is end cutting tool.
  • Different types of twist drills are:

a. Parallel Shank Jobbers Twist Drill

b. Parallel Shank Stub Series Twist Drill

c.  Parallel Shank Long Series Twist Drill

d. Taper Shank Twist Drill

 

a. Parallel Shank Jobbers Twist Drill

  • The Drill has two helical flutes with an equal shank of around a similar width as the cutting end.
  • The diameter of the drill range from 0.2 – 16 mm increasing by 0.02 – 0.03 mm in lower arrangement to 0.25 mm in higher arrangement.

b. Parallel Shank Stub Series Twist Drill

  • The drill is a shortened form of the equal shank twist drill, the shortening being on the flute length.

Parallel_Shank_Stub_Twist_Drill

Image : Parallel Shank Stub 

  • The diameter of the drill ranges from 0.5 – 40 mm increasing by 0.3 mm in lower series to 0.25 – 0.5 mm in higher series.

c.  Parallel Shank Long Series Twist Drill

  • It has two helical flutes with a parallel shank of approximately the shank diameter as the cutting end.
  • The overall length of this drill is the same as that of a taper shank twist drill of corresponding diameter.
  • The diameter varies from 1.5 – 26 mm increasing by 0.3 mm in lower series to 0.25 mm in higher series.

d. Taper Shank Twist Drill

  • It has two helical flutes with a taper shank for holding and driving the drill.
  • The shank for these drills conform to Morse tapers.
  • The diameter ranges from 3 – 100 mm.
  • The diameter increases by 0.3 mm in lowest series having Morse taper shank.

iv. Taper Shank Core Drill

  • These drills are planned for broadening cored, punched or penetrated gaps.
  • These drills can’t originate a hole in solid material because the cutting edges don’t extend to the center of the drill.
  • The metal is remove by a chamfered edge at the end of each flute.
  • The cutting action of a core drill is like to that of a rose reamer and it is regularly utilized as a roughing reamer.

v. Oil Tube Drill

  • It used for drilling deep holes.
  • This run lengthwise spirally through the body to carry oil directly to the cutting edges.

vi. Centre Drill

Center_Drill

Image : Center Drill

  • These are straight shank, two fluted twist drills used when centre holes are drilled on the ends of a shaft.
  • They are made in finer sizes.

Geometry of a Twist Drill

  • The following are the geometry of a twist drill are as follows :

1. Body

2. Flutes

3. Shank

4. Lips

5. Webs

6. Margin

7. Dead Centre

8. Lip relief angle

9. Point Angle

10. Helix Angle

11. Chisel Edge Angle

Drilling Machine | Definition, Types, Parts, Operation & Tools

Image : Geometry of a Twist Drill

1. Body

  • It is the piece of the drill that is fluted and eased.

2. Flutes

  • It forms the cutting edges on the point.
  • To allow the chips to escape.
  • To cause the chips to curl.
  • They permit the cutting fluid to reach the cutting edges.

3. Shank

  • It is that part of the drill which fits to the holding device.

4. Lips

  • It is the main cutting edges of the drill.

5. Webs

  • It is the metal column in the drill to separate the flutes.

6. Margin

  • It is the thin surface along the depression that decides the size of the drill and keeps the drill adjusted.

7. Dead Centre

  • It is a sharp edge at the tip end of the drill.

8. Lip relief angle

  • This is the axial relief angle at the outer corner of the lip.

9. Point Angle

  • This is the angle includes between the cutting lips projected upon a plane parallel to the drill axis and parallel to the cutting lips.

10. Helix Angle

  • It decides the rake edge of the front line of the drill.

11. Chisel Edge Angle

  • It is the angle between the chisel edge and the cutting lip.

Work Holding Device of Drilling Machine

  • The devices commonly use for holding the work in a Drilling Machine are as follows : 

1. T -bolt and Clamps

2. Drill Press Vise

3. Step Block

4. V -Block

5. Angle Plate

6. Drill Jigs

 

1. T -bolt and Clamps

  • This is one of the most common methods holding the work directly on the drilling machine table is by means of T -bolt and Clamps.
  • The diameter of T -bolts usually ranges from 15 – 20 mm.

T_-_bolt

Image : T -bolt

  • The clamp or straps are made of mild steel flats 12 – 20 mm thick and 45 – 70 mm wide.
  • Some of the common types of clamps are as follows :

i. Plain Slot Clamp

  • These are made of mild steel at having a central slot through which a T -bolt is made to pass.

ii. Goose Neck Clamp

  • This is use for holding work of sufficient height.
  • The clamps are sufficiently strong and are usually manufactured by forging.

iii. U -Clamp

U_Clamp

Image : U Clamp

  • Its very useful for quick adjustment of the work.
  • The clamp can be remove without removing the nut.

iv. Finger Clamp

  • They have a round or flat extension which may be fitted in a hole of the workpiece for clamping.

v. Adjustable Step Clamp

Use_of_Adjustable_Step_Clamp

Image : Adjustable Step Clamp

  • It has a screw at its one end which is used to level the clamp when its other end rests against the work.

2. Drill Press Vise

  • This is one of the most common methods of holding small and regular shaped workpieces.
  • This may be plain or universal type.
  • In a universal vise the base may be swiveled at any angle about the vertical axis and it may be tilted in a vertical plane to drill hole in a work at different angles.

3. Step Block

  • This is used in conjunction with T -bolts and clamps for holding the work directly on the table.
  • Its provide support for the other end of the clamp.
  • They made of mild steel.

4. V -Block

  • Its use for holding round workpieces.
  • They are accurately machined cast iron or steel blocks.

5. Angle Plate

Angle_Plate

Image : Angle Plate

  • These are usually made of cast iron having two faces at right angles to each other.
  • Its use when it is necessary to drill a hole parallel to another surface.

6. Drill Jigs

  • Its use for holding the work in a mass production process.
  • It can hold the work safely, find the work, and guide the device at any ideal position.

Tool Holding Devices

  • The different methods use for holding tools in a droll spindle are :

1. Directly Holding Tool

2. Sleeve

3. Socket

4. Drill Chucks

5. Special Attachments

 

1. Directly Holding Tool

  • All general purpose drilling machines have the spindle bored out to a standard taper to receive the taper shank of the tool.
  • The taper use in a drill spindle is usually Morse standard taper which is approximately 1: 20.
  • The tool may be removed by pressing a tapered wedge known as the drift into the slotted hole of the spindle.

2. Sleeve

  • The sleeve fits into the taper hole of the spindle and holds tool shanks of smaller sizes in the taper hole.
  • It has flat end or tang which fits into the slot of the spindle.
  • The sleeve with the device might be evacuated by compelling a float inside the opening of the axle and the device might be independent from the sleeve by the comparable procedure.

3. Socket

  • Drill attachments are any longer in size than the drill sleeves.
  • It consists of a solid shank attachment to the end of a cylindrical body.
  • The decrease shank of the attachment fits in with the decrease of the drill axle and fits into it.

4. Drill Chucks

  • It has taper shanks which fits into the drill machine spindle.
  • They are especially intended for holding smaller size drills or any other tools.

Applications of Drilling Machine

  • It use in the field of industries purpose like manufacturing, metalworking, etc,.
  • It use for producing holes like drilling, boring, etc,.
  • They also use in underground mining purpose.
  • Use for the purpose of under cutting.

Advantages of Drilling Machine

  • It requires less labor.
  • It gives high precision and accuracy.
  • No skill operators are required.
  • It consumes less floor area.

Disadvantages of Drilling Machine

  • It produces lots of torque at low speeds.
  • It is not suitable for small production methods.

For better understanding watch this video clip

External Links

 

Centrifugal Pump

  • Centrifugal Pump is one of the most common types of pumps used today’s world.
  • This was invented by Denis Papin in the 17th century, a French inventor.
  • It is a radial outward flow machine. And it’s commonly used to move liquids through a piping system.

Centrifugal Pump || Definition, Types, Parts, Working, and Diagram

Image : Centrifugal Pump

  • It acts as a reverse of an inward radial flow reaction turbine.
  • It converts mechanical energy from a motor to energy of moving fluid. Then some of the energy goes into kinetic energy of fluid motion and some into potential energy.
  • It’s represent a fluid pressure or by lifting the fluid against gravity to a higher level.

Definition of Centrifugal Pump

  • Centrifugal Pump is hydraulic machine which converts the mechanical energy into pressure energy by means of centrifugal force acting on the fluid.

Also Read :

Fluid, Definition, Properties, etc.

Cochran Boiler, Definition, etc.

Working Principle 

  • It chips away at the standard of constrained vertex stream. It means that when a certain amount of mass of fluid is allowed to rotate by an external torque, then pressure head may be raised by 

ω² r² / 2g 

  • It means that the rise in pressure head of the rotating liquid  is directly proportional to the square of the tangential velocity of the rotating liquid at any point.

Types of Centrifugal Pump

  • It classified as per following criteria : –

1. Working Head

2. Types of Casing

3. Specific Speed

4. Liquid Handled

5. Disposition of Shaft

6. Number of Impeller Per Shaft

7. Number of Entrance to the Impeller

8. Relative Direction of Flow Through Impeller

 

1. Working Head

  • It is the head at which water is delivered to the pump.
  • According to the range of working head, pump may divides into three categories :-

i. Low Lift Centrifugal Pump

ii. Medium Lift Centrifugal Pump

iii. High Lift Centrifugal Pump

 

i. Low Lift Centrifugal Pumps

  • This type of centrifugal pumps mean to work against head upto 15m.
  • Impeller is surrounded by a volute casing without providing guide vanes.

ii. Medium Lift Centrifugal Pump

  • This uses for head up to 40m and provides with guide vanes.

iii. High Lift Centrifugal Pump

  • This is used to delivered water at head 40m.
  • These types of centrifugal pumps are generally multistage pumps.

2. Types of Casing

  • The casing are of two types and pump is named after the casing it uses.

i. Volute Pump

ii. Turbine Pump or Diffusion Pump

 

i. Volute Pump

  • Volute is of a spiral form and the cross -sectional area of the moving stream gradually increases towards the delivery pipe.

ii. Turbine Pump or Diffusion Pump

  • In this types, impeller is surrounded by a guide wheel consists of a number of stationary vanes or diffuser with cross -section gradually enlarging towards periphery.
  • Generally, this arrangement employs in multistage pumps.
  • Water emerging from the impeller flows past the guide vanes and as the cross -section across flow increases, velocity falls and pressure is built up.

3. Specific Speed

  • It is defined as the speed of a geometrically similar pump which would deliver one cubic meter of liquid per second against a head of one meter.
  • It is denoted by Ns.
  • Specific speed of pump may be given as,

                          Ns = ( N √Q / H¾ )

                          Q = Discharge ( m³ )

                          H = Delivery Head ( m )

4. Liquid Handled

  • Depending on the type and viscosity of liquid to be pumped, the pump may be closed or open impeller.

5. Disposition of Shaft

  • The shaft may be disposes horizontally or vertically.
  • Generally, centrifugal pumps are designed with horizontal shafts.

6. Number of Impeller Per Shaft

  • According to this, pumps can be classified as :-

i. Single Stage Centrifugal Pump

ii. Multistage Centrifugal Pump

 

i. Single Stage Centrifugal Pump

  • It has one impeller provided on the shaft.

ii. Multistage Centrifugal Pump

  • It has two or more impellers provide on one shaft.

Function of Multistage Centrifugal Pump

  • To produce a high head.
  • To discharge a large quantity of liquid.

Advantages of Multistage Pumps

  • Less loss due to friction.
  • Small slip leakage.
  • Reduced stresses.
  • By proper arrangement of impellers, a thrust can eliminates.

Different Between Single Stage and Multistage Centrifugal Pump

S.NO. Single Stage Multistage
1. More frictional losses. Less frictional losses.
2. Larger axial thrust. Less axial thrust.
3. More slip leakage. Less slip leakage.
4. More stresses. Less stresses.
5. Low head. High head

7. Number of Entrance to the Impeller

  • In this type of pump, there is single entry or double entry of liquid provides on the side of impeller by means of suction pump.

8. Relative Direction of Flow Through Impeller

  • According to this, pump can be classified as :-

i. Radial Flow Pump

ii. Mixed Flow Pump

iii. Axial Flow Pump

i. Radial Flow Pump

  • For the most part, all divergent siphons are made with outspread stream impellers.

ii. Mixed Flow Pump

  • It is the modification of radial flow type and able to handle the large quantity of water.
  • Flow through the impeller is combination of radial and mixed flow.

iii. Axial Flow Pump

  • This type of pump is merely calls as centrifugal pump because centrifugal force is not use for generation of pressure.

Parts of a Centrifugal Pump

Main_Parts_of_Centrifugal_Pump

Image : Main Parts Of Centrifugal Pump

  • The main parts of a centrifugal pumps are:

1. Impeller

2. Casing

   a. Volute casing

   b. Vortex casing

   c. Casing with guide blades

3. Suction pipe

4. Delivery pipe

1. Impeller

  • It is a type of wheel with a series of backward curved vanes.
  • This is the main unit of pump which rotates the liquid by externally provided torque by motor.
  • On the impeller curve vanes are attached. The shape of vane or blade may be of following three types:

a. Backward vane

b. Forward vane

c. Radial vane

2. Casing

  • It is an air tight chamber that is surrounding the pump impeller.
  • This is similar to the casing of a reaction turbine. On the basis of casing, shape. They may be following three types:

 a. Volute casing

  • It is of spiral type in which cross -sectional area increases gradually as well as it surrounds the impeller.
  • The main functions of volute casing are:

i. To gather water from the impeller and to transmit it to the conveyance pipe at a steady speed.

ii. To increase the efficiency of the pump by eliminating the loss of head due to change of velocity.

 b. Vortex casing

  • In vortex casing, a circular chamber is provided between the casing and impeller.

c. Casing with guide blades

  • Guide blades are provided along the impeller peripheral hence called guide vanes.
  • The area of guide vane increases, thus reducing the velocity of flow through guide vane and correspondingly increasing the pressure of water. 

3. Suction pipe

  • A pipe whose one end connects to the inlet of the pump and other end dipped into the water in a sump calls as Suction pipe.

4. Delivery pipe

  • A pipe, whose one end attach to the outlet of the pump calls as delivery pipe.
  • Its other end delivers the water at required height.

Types of Head of a Centrifugal Pump

  • The Head of Centrifugal Pump may be expressed in the following ways :-

1. Suction Head

2. Delivery Head

3. Static Head

4. Manometric Head

1. Suction Head

  • It is the vertical height of the centre line of the centrifugal pumps above the water surface in the pump from which water is to be lifted.
  • It denotes by hs.

2. Delivery Head

  • It is the vertical height between the centre line of the pump and the water surface in the tank to which water is delivered.
  • It denotes by hd.

3. Static Head

  • The aggregate of suction head and conveyance head calls as static head.
  • It representes by Hs.

Hs = hs + hd

4. Manometric Head

  • It is defined as the head against which a centrifugal pumps has to work.
  • It denotes by Hmano.

Losses Occur in Centrifugal Pump

  • The various losses which occur in centrifugal pump are as follows :-

1. Hydraulic Losses

2. Mechanical Losses

3. Leakage Losses

1. Hydraulic Losses

  • Water driven misfortunes are the misfortunes happened by the liquid streaming in the siphon.
  • These losses are further classified into :-

i. Circular Flow Loss

ii. Fluid Friction Loss

iii. Shock Loss or Eddy Losses

i. Circular Flow Loss

  • Due to the flow taker place between two adjacent vanes, relative high pressure is formed along leading edge of vane indicates ( + ) in the travelling edge of blade relatively low pressure forms ( – ).

ii. Fluid Friction Loss

  • This loss depends on the area in contact with the fluid flow the roughness magnitude of the surface.
  • The loss can considers to vary as the square of the velocity.

iii. Shock Loss or Eddy Losses

  • This loss occurs due to improper entry angle of the flow with respect to the blade angle.
  • At configuration conditions this misfortune is essentially zero and increments at diminished or expanded stream from typical qualities.
  • Shock Loss occurs during two conditions :-

a. Reduction from normal discharge.

b. Increase from normal discharge.

2. Mechanical Losses

  • Mechanical losses are losses because of circle rubbing among impeller and fluid which occupies the leeway spaces among impeller and packaging.
  • These are likewise the misfortunes because of mechanical erosion in course, pressing organs.

3. Leakage Losses

  • Leakage loss in push balance gadgets, organ fixing and clearances between cut water and packaging and bearing seals.

Operational Difficulties in Centrifugal Pump

  • The operational difficulties are as follows :-
  • Pump fails to start pumping.
  • It is not working upto capacity and pressure.
  • Pump stops working.
  • Pump has very low efficiency.

Cavitation in Centrifugal Pump

  • Cavitation starts to show up in divergent siphons when the weight at the suction falls underneath the fume weight of the fluid.
  • The force of cavitation increments with the decline in estimation of NPSH.
  • In Centrigugal Pump, the pressur is lowest at the inlet of the impeller and hence vapour bubbles form in the suction region.

Centrifugal_Pump_Cavitation

 

  • These air pockets are conveyed alongside the streaming fluid to higher weight district close to the exit of impeller where these fume bubbles breakdown.
  • Because of abrupt crumbling of air pockets on metallic surface the high weight is made, which cause pitting activity on metallic surface and creates commotion and vibrations.
  • In this way cavities form on the metallic surface.

Definition of Cavitation

  • It is characterized as the marvel of development of fume air pockets of a streaming fluid in a locale where the weight of the fluid falls beneath its fume pressure and the unexpected crumbling of these fume rises in a district of higher weight.

 

Thoma’s Cavitation Factor for Centrifugal Pumps

σ =  [ ( Hb ) – ( HshLs ) ] / H

           = [ ( Hatm – Hv ) – Hs – hLs ] / H

       Where,

Hatm = Atmospheric pressure head in m of water or absolute pressure head at the liquid surface in pump.

Hv = Vapor pressure head in m of water.

  and

Hs = Suction pressure head in m of water.

HLs = Head lost because of grating in suction pipe.

and

H = Head developed by the pump.

Effects of Cavitation

  • The metallic surfaces are damaged and cavities are formed on the surfaces.
  • Due to sudden collapsing of vapour bubbles, considerable noise and vibrations are produced.
  • The efficiency of pump decreases due to cavitation.
  • Due to pitting action the surface of the pump blades becomes rough and the force exerted on water by the pump blades decreases.

Factors responsible for cavitation

  • High impeller speed.
  • Little width of suction funnel and gulf of impeller.
  • Too high specific speed.
  • Required NPSH > Available NPSH.
  • High temperature of flowing fluid.

Precautions

  • Pressure of flowing liquid in any part of the pump should not allow to fall below its vapour pressure.
  • Cavitation resistant material should be used.

Priming in Centrifugal Pump

Centrifugal Pump || Definition, Types, Parts, Working, and Diagram

Image : Priming

  • It is an operation in which suction pipe, casing of the pump and a portion of delivery pipe is completely filled with water by an outside source before starting the pump.
  • This is very essential step in start up of a centrifugal pump. Facts is that centrifugal pump are not capable of pumping air or vapours.
  • In priming, centrifugal pump will get fully sub merged in liquid without any air trap inside. This is particularly required when there is a first beginning up.

Necessary of Priming

  • The preparing of positive relocation siphons require uniquely at the hour of first beginning.
  • For this situation preparing implies filling fluid in packaging and expect to lessen the freedom volume.
  • It tends to be expelled the air by their own siphoning activity. This calls Self Priming.
  • Priming is not require in reciprocating pumps. But a centrifugal pump is not self priming, Hence priming is necessary.

In other words

  • The density of air is low, so head generated by pump is also low even negligible and hence water not be sucked by the pump.
  • To avoid this difficulty priming of centrifugal pump is necessary.

Method of Priming

  • The pumps can be primed by any of the following methods :-

1. Manually

2. With jet pump

3. With seperator 

4. With vacuum pump

1. Manually

Manually_Priming

 

  • In this strategy, water is poured in the siphon through channel.
  • When preparing is being done, an air escapes through air vent valve.

2. With jet pump

With_Jet_Pump

Image : With jet pump

  • In this technique, water accessible at high head permits to move through a spout.
  • The spout is intended to the point that at the fly outside the spout the weight is not exactly the atm pressure so it is conceivable to suck water from the sump.

3. With seperator 

  • In this strategy, air seperator is given on the conveyance side of siphon and bowed suction pipe divide is given at the gulf of the siphon.
  • Bent suction pipe portion always contain some liquid.
  • The fluid heavier than air, so it falls once again into seperator and air moves upward way.
  • Accordingly the fluid and air are seperated in seperator.

4. With vacuum pump

With_Vacuum_Pump

Image : With vacuum pump

  • In this strategy, the little size responding siphon is utilized preparing radial siphon.
  • The suction line of responding siphon associates with the conveyance line of principle radiating siphon. 

Different Between Centrifugal Pump & Reciprocating Pump

S. NO. Centrifugal Pump Reciprocating Pump
1. It gives large discharge and less head. It gives high head and small discharge.
2. Priming needs. It is self primed.
3. It is simple in construction. Complicated construction.
4. Maintenance cost is low. Maintenance cost is high.
5. Flywheel is not used. Flywheel is used.
6. Installation cost is high. High installation cost.
7. Efficiency is high. Low efficiency.
8. Starting torque is more. Low starting torque.
9. Handle highly viscous fluid. It can handle low viscous fluid.
10. It needs no air vessel. Air vessel uses.

Advantages of Centrifugal Pump

  • The expense of a radial siphon is less as it has less parts.
  • Installation and maintenance are easier and cheaper.
  • It can operates at high speed.
  • It very well may be straightforwardly coupled to an electric engine or an oil motor.

Disadvantages of Centrifugal Pump 

  • Produce cavitation.
  • Poor suction power.
  • Corrosion.
  • Can’t deals with viscous fluids like mud and waste.
  • Can’t be able to work high speed.

Applications of Centrifugal Pump

  • Almost 70 – 80 % Centrifugal Pumps are using in industry or for domestic purpose.
  • Its also using in the field of Food, Chemical, Petrochemical Industries.
  • In the field of irrigation and water supply.
  • Mining etc.

Conclusion

  • Centrifugal Pumps mostly use for commercial purpose and have simple shape so ultimately its cost effective.
  • There working mechanism is simple.
  • They have less power consumption.
  • It can be use to pump suspended or toxic fluids.
  • They may not use for volatile or viscous fluids.

For Better Understanding Watch This Video

External Link

 

Introduction

  • Concrete is a very strong and mouldable (comes in any shape) construction material.
  • This can continue to harden and gains strength over many years.
  • It has a very long history. 
  • The Ancient Romans weren’t the first to make concrete.
  • Romans were first to utilize this material widespread around 600 BC.
  • The Romans successfully implemented the use of concrete in the majority of their construction around 200 BC.
  • It wasn’t until 1793 that this innovation took a major jump forward when John Smeaton found an increasingly present day technique for delivering water driven lime for concrete.
  • In 1824 Joseph Aspdin designed Portland concrete by consuming finely ground chalk and dirt until the carbon dioxide was evacuated. 
  • After that the first widespread use of concrete in home construction was in England and France between 1850 and 1880 byFrancois Coignet.
  • In the nineteenth Century, concrete was utilized for the most part for mechanical structures.

Definition of Concrete 

  • This is the most advance technology which is a mixture of cement, sand, pebbles or crushed rock and water that becomes hard like a stone after a specified days of curing.

Components of RCC Concrete

1. Cement

2. Fine Aggregates ( Sand )

3. Coarse Aggregates ( Pebbles )

4. Steel

5. Water

6. Admixture

1. Cement

  • This is one of the major part of concrete which plays a binding work for whole the components.
  • If you want to know more about Cement than touch my link Cement under:

                                   Cement

2. Fine Aggregates ( Sand )

  • Sand is a granular material made out of finely isolated stone and mineral particles.

3. Coarse Aggregates ( Pebbles )

  • Coarse aggregates are construction component made of rock quarried from ground deposits.

4. Steel

  • Steel is fundamentally an alloy of iron and carbon, with the the carbon content varying up to 1.5 %.

5. Water

  • Water is abundant in nature which uses in construction work but free from natural impurities.

6. Admixture

  • It is a type of chemical uses in concretes production to increase or decrease its setting time in the construction field.
  • It only uses in the big construction work where transportation facility is far from pouring site.
  • The use of this chemical is not in practice in smaller works like making home, etc.

Types of Concrete

1. Reinforced Cement Concrete

2. Plain Cement Concrete

3. Ready -mix Concretes

4. Light weight Concretes

5. Fiber reinforced Concrete

6. Green Concrete

1. Reinforced Cement Concretes ( R C C )

RCC

 

  • It is the combination of ordinary concrete with the steel to increase its compressive and tensile strength to a great extent.
  • Widely use of this in the construction field.
  • It reduces the size of structure.
  • Sizes reduce but load bearing capacity increases.
  • So, Today’s world likes this most.
  • It saves money due to reduce size of structure.
  • In old age, due to no use of R C C, size of place increase and also takes wide area for making place.
  • For example :-

                    a. Buildings

                    b. Flyover

                    c. Highways roads traffic

                    d. Hydro -power plants

                    e. Tunnels

                    f. Irrigation canals

                    g. Drains ,etc.  

2. Plain Cement Concretes ( P C C )

PCC

 

  • It is the mixture of cement, fine aggregate, and coarse aggregate without steel.
  • It is popularly known as P C C.
  • Before starting any R C C work on ground, we first do P C C work to stop corrosion of steel.
  • Save main structure from bacterial attack.

3. Ready -mix Concretes

RMC

 

  • It never prepares on the job site.
  • This prepares at central plant on a fixed batch.
  • It is fully machinery made mix.
  • Making construction work of this is on huge scale.

4. Light weight Concretes

LWC

 

  • It is a type of mixture that is made with a light weight coarse aggregate and five aggregate which may be light weight.
  • It oftens used in house construction.
  • Decrease in dead loads making reserve funds in establishments and fortification.
  • Improved thermal properties.
  • Improved fore resistances.
  • Reduction in form work.

5. Fiber reinforced Concretes

FRC

 

  • It is a mixture of cement, mortar or concrete with suitable fibers.
  • Increases the tensile strength of the concrete.
  • Reduces the air voids & water voids.
  • This increases the durability of the concrete.
  • It’s compressive strength is not enough.
  • It does not prefer for heavy structure.

6. Green Concretes

Cycle of Green Concrete

 

  • The concrete is made with concretes wastes which are Eco – friendly so called as Green concrete.
  • Better Performance                                                                 
  • Enhance cohesion work ability / consistency
  • Reduce shrinkage / creep.
  • Durability – Better service life of concretes
  • Reduce carbon footprint
  • Optimizes use of available materials
  • No increase in cost
  • LID India Certification
  • If you want to know more about Green Concretes than touch my link Green Concretes under :-

Green Concrete

Properties of Concrete

  • High compressive strength.
  • Free from corrosion and there is no appreciable effect of atmospheric agents on it.
  • It solidifies with age and the way toward solidifying proceeds for quite a while.
  • This proves more economical than steel.
  • It binds rapidly with steel.
  • This is weak in tension.
  • Have a tendency to shrink.
  • It has a tendency to be porous.
  • It frames a hard surface, equipped for opposing scraped spot.
  • When it is fresh, it should have enough workability so that it can place in the formwork easily.
  • It must possess maximum density or in other words, it should be the strongest and the most watertight.
  • The cost of materials and labor require to form the concretes should minimum. 

Different Methods of Proportioning Concrete

  • There are different methods as follows :-

1. Arbitrary Method

2. Fineness Modulus Method

3. Minimum Voids Method

4. Maximum Density Method

5. Water Cement Ratio Method

1. Arbitrary Method
  • In this method, there is no rigid control on the strength of the concretes mix. However this method widely uses for all works of small magnitude because of its simplicity in the design.
  • Known mixes of concrete is as under :-
Proportion of Concrete Mix Maximum size of Aggregate Nature of Work
1 : 1 : 2 12 – 20 mm Heavily loaded RCC columns and Arches.
1 : 2 : 2 12 – 20 mm Small precast members.
1 : 1.5 : 3 20 mm Water retaining structures.
1 : 2 : 3 or 1 : 3.66 : 3.33 20 mm Water tank, bridge construction, etc.
1 : 2.5 : 3.5 25 mm Footpath and road work.
1 : 2 : 4 40 mm General RCC work.
1 : 3 : 6 50 mm Mass concreting work in culverts, etc.
1: 4 : 8 or 1 : 5 : 10 or 1 : 6 : 12 60 mm Heavy walls and foundation footings, etc.
2. Fineness Modulus Method
  • The term fineness modulus s uses to show a file number which is harsh corresponding to the normal size of the molecule in the whole amount of total.
  • Let P be the designed fineness modulus for a concretes mix of fine and coarse aggregates.

Then

   R = [( P2 – P ) / ( P – P1 ) ] × 100 

Where   

    R = Proportion of fine total to the joined total by weight.

    P1 = fineness modulus of fine aggregate.

    P2 = fineness modulus of coarse aggregates.

3. Minimum Voids Method
  • In this method, the voids of coarse aggregate and fine aggregate determine separately and to get the dense concrete, it is so arranged that :

a. The quantity of fine aggregate completely fills the voids of the coarse aggregate.

b. The quantity of cement completely fills the voids of the fine aggregate.

c. Sufficient water adds to the mix of cement, fine aggregate and coarse aggregate to make the mix workable.

4. Maximum Density Method
  • This methods bases on the principle that the densest concretes achieves by proportioning its aggregates in such a manner that the heaviest weight of concrete for same volume obtains.
  • This method of maximum density is not very popular mainly because of the following two reasons :

a. The grading can not accurately achieve.

b. There is no control over the strength of concretes.

5. Water Cement Ratio Method

Water_Cement_Ratio

 

  • As per water cement ratio law by Abram, the strength of well compact concretes with good workability depends only on the water cement ratio.
  • By applying this law, concretes assumes to be fully compact.
  • The lower water content produces stiff paste.
  • Water cement ratio within certain limits results in the increase strength.
  • Similarly the higher water content increases the workability but it is not useful for the chemical reaction.
  • The excess water evaporates leaving pores in the concrete thus the increase water cement ratio lowers the strength of concretes.

 Workability of Concrete

  • Workability is the amount of work to produce full compaction.
  • The important facts in connection with workability are :

1. If more water adds to attain the required degree of workmanship, it results into concretes of low strength and poor durability.

2. If the strength of concretes affects, the degree of workability can obtain.

  • By slightlying changing the proportions of fine and coarse aggregates, in case the concretes mixture is too wet, and
  • By adding a small quantity of water cement paste in the proportion of original mix, in case the concretes mixture is too dry.

3. The workability of concretes also affects by the maximum size of the coarse aggregates to use in the mixture.

4. The workability of concrete affects mainly by water content, water cement ratio and aggregate cement ratio.

 Factors Affecting Workability

  • Following are the elements which influence the usefulness of Concrete.

1. Water Content

2. Mix Proportions

3. Size of Aggregates

4. Shape of Aggregates

 1. Water Content

  • Water content of concretes have sufficient influence on the workability.
  • The high the water content per cubic meter of cements, the higher will be the smoothness of cements which is one of the significant factor influencing usefulness.

2. Mix Proportions

  • Total / Cement proportion is a significant factor impacting functionality.
  • The higher aggregate -cement ratio as well as leaner is the concretes.
  • In lean concretes, less quantity of paste is available for providing lubrication per unit surface area of aggregate and hence the mobility of aggregate restrains.
  • In case of rich concretes with lower aggregate -cement ratio, more paste is available to make the mix cohesive and fatty to give better workability.

3. Size of Aggregates

  • The bigger the size of the aggregate, lesser is the surface area and hence less amount of water requires for wetting the surface and less matrix of paste requires for lubricating the surface to reduce internal friction.
  • For a given quantity of water and paste, bigger size of aggregates give higher workability.

4. Shape of Aggregates

  • The shape of aggregates influences workability to a large extent.
  • Angular, elongated or flaky aggregate makes the concretes very harsh when compare to round or cubical shape  aggregates.
  • Adjusted totals have less surface zone and less voids than rakish or flaky total, not just that, being round fit as a fiddle, the frictional obstruction is additionally extraordinarily diminished.
  • Because of above reason, river sand and gravel provide greater workability to concretes than crushed aggregate and sand.

 Concrete Tests

1. Slump Test

2. Flow Test

3. Vee -Bee Test

4. Compaction factor Test

5. Vee -Bee Consistometer Test

1. Slump Test

Concrete || Definition, Components, Types, Properties, Grade & Tests

  • It is the most generally utilized strategy for estimating consistency of cement.
  • This test also tells about workability.
  • It is not a suitable method for very wet or very dry concretes.
  • It doesn’t measures all factors contributing to workability.
  • The diameter of the rod is 16mm and its length is 60cm.
  • The dimensions of Slump Test Apparatus is as under :

Slump_Test

Advantages of Slump Test

  • Easily detect the difference in water content of successive batches of concretes.
  • The apparatus is cheep, portable and convenient to be used at site.

Limitations of Slump Test

  • It occurs only in case of plastic mixes.
  • It doesn’t occur in case of dry mixes.
  • There is no immediate connection between the functionality and the estimation of droop.
  • It is not suitable for a concrete in which maximum size of aggregates exceeds 40mm.
  • There are chance of many shapes of slump to occur and it is difficult to decide which one is giving the correct value.

2. Flow Test

Flow_Test_Apparatus

  • This is a research center test which gives a sign of the nature of cement regarding consistency, cohesiveness and the inclination to isolation.
  • In this test, a standard mass of cement is exposed to shocking.
  • The dimensions of Flow Test Apparatus is as under :-

Concrete || Definition, Components, Types, Properties, Grade & Tests

3. Vee -Bee Test

  • This test is preferred for finding workability of stiff concretes mix having very low workability.

4. Compaction factor Test

  • In this test, the degree of workability of concrete measures in terms of internal energy required to compact the concrete thoroughly.
  • This test designs for the use in the laboratory but it can also use in the field.
  • The degree of compaction calls the compacting factor which measures by the density ratio.

 

      C. F = Wt. of partially compacted concrete / Wt. of fully compacted concrete

 

5. Vee -Bee Consistometer Test

  • It is a good measure indirectly the workability of concretes.
  • This test consist of a vibrating table, a metal pot and a standard iron rod.

Grade of Concrete

  • Level of Concrete is characterized as the base quality of the solid must groups following 28 days of development with appropriate quality control.
  •  It is denoted by prefixing M.
  • For example : M10, M15, M20, M25, M30, M35, etc. where M stands for Design mix and the numbers represents specified strength in N / mm² after 28 days of curing.

Concrete Mix Design

  • When the task of deciding the proportion of the constituents of concretes decides by the use of certain relationships, the concretes thus produces terms as design mix concrete.
  •  Concrete Mix design procedure for a particular grade of concretes depends on the following requirements :
  • Characteristic strength of concretes.
  • Degree of workability.
  • Specific gravity and bulk density of cement.
  • Grading zone of fine aggregate and size of coarse aggregates.
  • Specific gravity and bulk density of coarse and fine aggregates.
  • Moisture content.

Steps for Concrete Mix Design is as follows :

1. Target mean strength and standard deviation

2. Selection of water -cement ratio

3. Selection of water content

4. Calculation of cementations material content

5. Estimation of coarse aggregates

6. Estimation of mass of coarse aggregates

7. Correction for actual site conditions

Nominal Mix Concrete

  • Nominal Mix Concrete is a concrete which uses where the quality control requirement for design mixes are difficult to implement. 

Curing of Concrete

  • Curing is a process of making concrete surface wet for a certain period of time so as to promote the hardening of cement.
  • The curing period is about 7 – 14 or 28 days.
Purpose of Curing
  • It protects the concretes surfaces from sun and wind.
  • The strength of concretes increases with age when curing is efficient.
  • By proper curing, the durability and impermeability of concretes increases and shrinkage reduces.
Effects of Improper Curing
  • The rate of carbonation increases.
  • Frost and weathering resistance decreases.
  • The durability decreases due to higher permeability.
  • Cracks are formed.
Methods of Curing
  • Ponding with water.
  • Covering concrete with wet jute bags.
  • Covering concrete with water proof paper.
  • Spraying with water.
  • Continuous sprinkling of water.
  • Applying curing compounds.

The best among all methods above is Ponding.

Precautions in Concrete Construction

  Following Precaution should be observed :

  • Concrete ought to be crisp and liberated from set concrete particles.
  • Aggregates should be well graded and free from dirt, etc.
  • Blending water ought to be liberated from unsafe synthetic compounds and remote materials.
  • Prepared concrete each time should be used and finished within 30 minutes or initial setting time of cement.
  • Concretes should prepare on rigid and water tight platform without loosing any cement or water.
  • Complete blending of fixings either by hand or by blender ought to be guaranteed.
  • Care should be taken to avoid bleeding and segregation during transporting or placing concrete.
  • The form work on which concrete lay must check for its rigidity.
  • Laid concrete must compact thoroughly by manual tamping or mechanical vibration.
  • During bad weather conditions, precautions for concreting should be taken.

For better understanding watch this video clip

 https://mechanicalnotes.com/cement-definition-introduction-types-composition-and-tests/   

External Link

Introduction

  • Cement is a binding material.
  • It was first invented by Egyptians.
  • The manufacturing of cement was started in England around 1825.
  • Joseph Aspdin manufactured it and calls it Portland cement.

Cement || Definition, Introduction, Types, Composition and Tests

 

  • Portland cement because when it hardens, it produces a material resembling stone from the quarries near Portland in England.
  •  It obtains by burning together a mixture of naturally occurring argillaceous  and calcareous materials at high temperature.
  • The product obtained on burning called clinker.
  • Clinker cools and grinds to the required fineness to produce a material known as cement.

Definition of Cement

  • Cement is an extremely fine material having adhesive and cohesive properties which provide a binding medium for the discrete ingredients.

Chemical Composition of Cement

  • The materials use for the manufacturing consist mainly of Lime, Silica, Alumina and Iron oxide.
  • Oxides presents in the raw materials when subjects to high clinkering temperature combined with each other to form complex compounds.
  • The identification of the major complex compounds is based on R.H. Bogue’s work and hence these are calls Bogue’s compounds.
  • In addition to the four major components, there are mainly minor compounds form in the kiln.
  • The influence of these minor compounds on the properties of cement or hydrated compounds is not sufficient.
  • Two of the minor oxides namely K2O and Na2O referrers to as alkalies in cement are of some importance.
Constituents Percentage Average Percentage
Lime ( CaO ) 62 – 67 % 62
Silica ( SiO2 ) 17 – 25 %  22
Alumina ( Al2O3 ) 3 – 8 % 5
Calcium Sulphate ( CaSO4 ) 3 – 4 % 4
Iron Oxide ( Fe2O3 ) 3 – 4  % 3
Magnesia ( MgO ) 0.1 – 3 % 2
Sulphur 1 – 3 % 1
Soda and Potash ( Na2O + K2O ) 0.5 – 1.3 % 1

 Bogue’s compounds:-

Name Chemical Formula Percentage
Tricalcium Silicate ( C3S ) 3CaOSIO2 30 – 50 %
Dicalcium Silicate ( C2S ) 2CaOSiO2 20 – 45 %
Tricalcium Aluminate ( C3A ) 3CaOAl2O3 8 – 12 %
Tetracalcium Alumino Ferrite ( C4AF ) 4CaOAl2O3Fe2O3 6 – 10 %

Representation of the composition of Bogue’s compounds is as follows :-

Bogue's_Compound

Functions of Various Cement Ingredients

1. Lime ( CaO )

  • Important Ingredient.
  • Proportion should carefully maintain.
  • Excess lime makes it unsound and causes it to expand & disintegrate.
  • Lime deficiency decreases strength and cause quick setting.

2. Silica ( SiO2 )

  • Important Ingredient.
  • Provides strength.
  • Excess quantity increases strength  but  also increases setting time.

3. Alumina ( Al2O3 )

  • Imparts quick setting.
  • Lowers the clinkering temperature.
  • Use of excess amount decreases strength.

4. Calcium Sulphate ( CaSO4 )

  • This ingredient is in the form of gypsum.
  • Increases the initial setting time.

5. Iron Oxide ( Fe2O3 )

  • Gives colour.
  • Provides hardness.
  • Imparts strength.

6. Magnesia ( MgO )

  • Small amount provides hardness and colour.
  • High content makes unsound.

7. Sulphur ( S )

  • Small amount is useful in making sound cement.
  • Excess content causes unsoundness.

8. Alkalies

  • Excess content causes alkali -aggregate reaction and efflorescence.

Basic Properties of cement Compounds

  • C3S and C2S which together constitute about 70 – 80 %.
  • C3S produces at a faster rate of reaction accompanied by greater heat evolution and imparts early strength.
  • A higher percentage of C3S results in rapid hardening with an early gain in strength with a higher heat of hydration.
  • C2S hydrates and hardens slowly and provides much of the ultimate strength.
  • A higher percentage of C2S results in slow hardening, less heat of hydration and greater resistance to chemical attack.
  • C3A is characteristically fast reacting with water and may lead to an immediate stiffening of paste and this process is known as Flash set.
  • The role of gypsum added in the manufacture of cement is to prevent such a fast reaction.
  • C3A provides weak resistance against Sulphate attack and it’s contribution to the development of strength is perhaps less significant than that of C3S and C2S.
  • Like C3A, C4AF also hydrates rapidly but it individual contribution to the overall strength is insignificant. However, it is more stable than C3A.

Hydration of Cement

    • The chemical reactions that take place between cement and water is known as hydration of cement.
    • This reaction is exothermic which liberates a considerable quantity of heat and this liberates heat is called as heat of hydration.
    • The hydration process is not an instantaneous one.
    • The reaction is faster in the early periods and continues indefinitely at a decreasing rate.
    • During the hydration, C3S and C2S react with water and calcium silicate hydrate forms along with calcium hydroxide [ Ca ( OH )2 ].
    • Calcium silicate is the most important product of hydration and it determines the good properties of concrete.

    2C3S + 6H → C3S2H3 + 3Ca ( OH )2

  •  and
  • 2C2S + 4H → C3S2H3 + Ca (OH )2

    • It can see from the above reactions that C3S produces a less quantity of calcium silicate and more quantity of calcium hydroxide than that forms in the hydration of C2S.

Types of Cement

  • There are different types of cement as classified as follows :-

1. Ordinary Portland Cements 

      a. 33 Grade

      b. 43 Grade

      c. 53 Grade

2. Rapid Hardening Cements 

3. Extra Rapid Hardening Cements 

4. Low Heat Portland Cements 

5. Portland Slag Cements

6. Portland Pozzolana cements

7. Sulphate Resisting  Portland Cements

8. White Portland Cements

9. Coloured Portland Cements

10. Hydrophobic Cements

11. High Alumina Cements

12. Super Sulphated Cements

13. Special Cements

      a. Masonry Cements

      b. Air Entraining Cement

      c. Expansive Cements

      d. Oil Well Cements

1. Ordinary Portland Cements ( OPC )
  • Also known as setting cements.
  • It is the basic Portland cements and manufactures in large quantities than all other cements.
  • It is presently available in three different grades viz. C33, C43 and C53.
  • The numbers 33, 43 and 53 correspond to the 28 days compressive strength of cement as obtain from standard tests on cement -sand mortar specimens.
  • It uses in general concrete construction. 
2. Rapid Hardening Cements ( RHC )
  • It is finer than ordinary Portland cements.
  • It contains more C3S and less C2S than OPC.
  • The one day strength of this is equal to the 3 days strength of OPC with the same water cement ratio.
  • The main advantage of rapid hardening cement is that shuttering may be removed much earlier, thus saving considerable time and expenses.
  • RHC is also used for road work where it is imperative to open the road traffic with the minimum delay.
3. Extra Rapid Hardening Cements ( ERHC ) 
  • It is obtains by mixing calcium chloride with RHC.
  • Addition of CaCl2 imparts quick setting properties in extra RHC.
  • The acceleration of setting, hardening and evolution of heat in the early period of hydration makes this cement very suitable for concreting in cold weathers.
  • The 1 or 2 day strength of extra RHC is 25% more than that of RHC.
  • The gain of strength disappears with age and 90 days strength of extra RHC andRHC are nearly the same.
  • Use of extra RHC prohibits in prestressed concrete construction.

Also read : Green Concrete

4. Low Heat Portland Cements 
  • It is a Portland cement which obtains by reducing the more rapidly hydrating compounds, C3S and C3A and increasing C2S.
  • The heat of hydration of low -heat cement shall be as follows :-
  • 7 days – not more than 65 calories per gm
  • 28 days – not more than 75 calories per gm
  • Since, the rate of gain of strength of this cements is slow, hence adequate percaution should be taken in this use such as with regard to removal of formwork, etc.
  • LHC uses in massive construction works like abutments, retaining walls, dams, etc. where the rate at which the heat can be lost at the surface is lower than at which the heat is initially generated.
  • It has low rate of gain of strength, but the ultimate is practically the same as that of OPC.
5. Portland Slag Cements ( PSC )
  • PSC makes by intergrinding  portland cements clinker and granulated blast furnace slag.
  • The proportion of the slag being not less than 25 % or more than 65 % by weight of cement.
  • The slag should granulate blast furnace slag of high lime content, which produces by rapid quenching of molten slag obtain during the manufacture of pig iron in a blast furnace.
  • In general blast furnace slag cement finds to gain strength more slowly than the ordinary portland cement.
  • The heat of hydration of portland blast furnace slag cements is lower than that of OPC. So, this cement can use for mass concreting but is unsuitable for cold weather.
  • It has fairly high sulphate resistance, rendering it suitable for use in environments exposed to sulphates.
  • It uses for all purpose for which ordinary portland cement uses.
  • Because of its low heat evolution, it can use in mass concrete structure such as dams, foundations and bridge abutments.
6. Portland Pozzolana Cements ( PPC )
  • It can produce either by grinding together portland cement clinker and pozzolana with the addition of gypsum or by blending uniformly portland cement and fine pozzolana.
  • PPC produces less heat of hydration and offers great resistance to the attack of impurities in water than OPC.
  • PPC is particularly useful in marine and hydration constructions, and other mass concrete structures.
  • The disadvantage of using PPC is that the reduction in alkalinity reduces the resistance to corrosion of steel reinforcement.
  • This cement has higher resistance to chemical agencies and to sea water because of absence of lime.
  • It evolves less heat and its initial strength is less but final strength is equal to OPC.
  • It has lower rate of development of strength than OPC.
7. Sulphate Resisting Cements ( SRC )
  • The portland with low C3A and C4AF and ground finer than OPC is known as sulphate resisting cements.
  • This cement is ” Sulphate resistant ” because the disintegration of concrete causes the reaction of C3A in harden cements with a sulphate salt from outside is inhibited.
  • It uses in marine structures, sewage treatment works, and in foundations and basements where soil is infests with sulphates.
  • However, recent research indicates that the use of sulphate resisting cement is not beneficial in environments where chlorides are present.
8. White Portland Cements
  • The process of manufacturing white cement is the same but the amount of iron oxide which is responsible for grayish colour is limited to less than 1 %.
  • Sodium Alumino Ferrite adds to act as flux in the absence of iron oxide.
  • The properties of white cement is nearly same as OPC.
  • Whitness of white cement measures ISI scale or Hunter’s scale.
  • Grey colour of OPC is due to the presence of iron oxide. Hence in white cement, Fe2O3 is limited to 1 %.
9. Coloured Portland Cements
  • It is a type of mixture of  white cements along with the desired colour and color determines its original presence.
  • The cost of this cement is high than OPC.
10. Hydrophobic Cements
  • It obtains by intergrinding OPC with 0.1 – 0.4 % of water repellant film -forming substance such as oleic acid or stearic acid.
  • The properties of hydrophobic cements are nearly the same as that of OPC.
  • The cost of this cement is high than OPC.
11. High Alumina Cements ( HAC )
  • It is very different in composition from portland cements.
  • It characterizes by its dark color , high early strength , high heat of hydration and resistance to chemical attack.
  • The raw material uses for its manufacture consists of limestone and bauxite which is a special clay with high alumina content.
  • It has a good resistance against sulphates and some dilute acids, and particularly recommend in marine environments.
  • It has an initial setting time of 4 hrs and final setting of about 5 hrs.
  • High alumina cement is very expensive to manufacture.
  • It uses where early removal of the framework is required.
  • Its rapid hardening properties arise from the presence of calcium aluminate.
  • This must not mix with any other types of cements.
12. Super Sulphated Cements ( SSC )
  • It obtains from well granulated blast furnace slag, calcium sulphate and OPC.
  • It is ground finer than OPC.
  • This has low heat of hydration.
  • It is used for construction of dams and other mass concreting works.
  • It has high resistance to chemical attack.
13. Special Cements
  • It has some specific function such as altering the setting or hardening behavior of a concrete.

Field Tests For Cements

  • Colour : Grey color with a light greenish shade.
  • Physical properties : Cement should feel smooth when rubs in between the fingers.
  • If hand is inserted in a bag, it should feel cool.
  • If a small quantity of cement throw in a bucket of water, it should sink and should not float on the surface.
  • Presence of lumps : Cement should free from lumps.

Laboratory Test of Cements

1.Chemical composition 

2. Normal ( standard ) consistency

3. Initial and final setting time

4. Soundness

5. Strength

6. Fineness

7. Heat of hydration 

8. Specific gravity

1.Chemical Composition Test
  • This is the type of test in which the ratio of percentage of lime to percentage of silica, alumina and iron oxide, when calculated by the formula  ( CaO – 0.7SO3 ) / ( 2.8SiO2 + 1.2Al2O3 + 0.65Fe2O3 ) shall not be greater than 1.02 and not less than 0.66.
2. Normal ( standard ) Consistency Test
  • The normal consistency of a cement paste is defined as that consistency which will permit a Vicat plunger having 10mm diameter and 50mm length to penetrate a depth of 33 to 35mm from the top of the mould.
3. Initial and Final setting time Test
  • Initial setting time test is a test that is the time elapses between the moment that the water is added to the cement, to the time that the paste starts losing its plasticity.
  • Final setting time test is a test that is the time elapses between the moment that the water is added to the cement and the time when the paste has completely losses its plasticity and has attains sufficient firmness to resist certain definite pressure.
4. Soundness Test
  • Soundness of cement indicates that the cement paste, once it has set, does not undergo change in volume causing concrete to crack.
5. Strength Test
  • Strength test is determined by compressive strength test and tensile strength test.
6. Fineness Test 
  • Fineness test is the major of the size of the cement particles in the term of specific surface.
7. Heat of hydration Test
  • Heat evolves during hydration of cement, the amount being dependent on the relative quantity of clinker compounds.
  • The apparatus uses to determine the heat of hydration of cement is known as Calorimeter.
8. Specific gravity Test
  • It is obtained by Le Chatelier’s flask.

       Specific gravity = Weight of Cement / Weight of Displaced volume of Liquid 

For better understanding watch this video clip

Milling ( Machine )

  • Milling  is the backbone of the manufacturing industries.
  • Nearly it can do any processing activity whether it is gear processing, string processing, precise processing, and so on.
  • The main processing machine appeared in around 1770 and was of French starting point.
  • The processing shaper was first created by Jacques De Vaucanson in the year 1782.

Definition of Milling ( Machine )

  • Milling is the machining process of using rotary cutters to remove material by advancing a cutter into a work piece.
  • This may be done varying direction at an angle with the axis, cutter head speed, and pressure.
  • Milling can be done with wide range of machine tools.

Also read:

 

Principal & Working of Milling Machine

Principal

  • A milling machine removes metal by rotating a multi -point cutting tool against a work piece.
  • The work piece or jobs are fixed on the work table and feed is given against the tool.

       The table can be given three type of movements:

   1. Longitudinal cross wise

   2. Vertical movements

   3. Rotational movements

Working_Principle_of_Milling_Machine

Fig. Working -Principle

Working

  • The work is rigidly clamped on the table of the machine and multi teeth cutter will revolving either on a spindle.
  • The cutter has many cutting edges and is rotated at high speeds.
  • The work can be fed in a longitudinal, vertical, or cross direction.
  • For further process, the cutter teeth remove the metal from the work surface to produce desired shape like flat, circular, or curved.

Main Parts of Milling Machine

  • The main Parts of Milling machine are as follows:

Main Parts of Milling Machine

Image. Main Parts of Milling Machine

    1. Base 

    2. Column

  3. Knee

   4. Power Feed Mechanism

  5. Saddle

  6. Table

  7. Spindle

  8. Over  Arm

  9. Arbor

  10. Ram

  1. Base 

  • Base is the lowermost part to support the machine.
  • It is a dim iron throwing precisely machined on its top and base surface and fills in as an establishment part for the various parts which rest upon it.

2. Column

  •  It is the vertical part that is fixed on the base.
  • The segment is box formed, vigorously ribbed inside and houses all the driving instruments for the shaft and table feed.
  • Front vertical face of column is provided with a vertical slide which can be square or of dovetail type.
  • The knee is made of cast iron which slides up and down on the vertical slide ( guide ways ) on the face of column.

3. Knee

  • The knee is an unbending dark iron throwing that slides all over on the vertical methods for the section face.
  • The knee houses the feed system of the table, and various controls to work it.
  • The top essence of the knee shapes a slide route for the seat to give cross travel of the table. 

4. Power Feed Mechanism

  • It is the knee which contains the force feed component.
  • It’s use to control the longitudinal ( left & right ), transverse ( in & out ) and vertical ( up & down ) feeds.

5. Saddle

  • Saddle is present on the knee which supports the table.
  • It is proving motion in the X and Y axes by means of lead screw.

6. Table

  • The table is present on the top of the saddle and can be moved along the X axes.
  • It contains several T – slots for the mounting of work piece or clamping jigs & fixtures.

7. Spindle

  • Spindle is the hollow shaft that is use to hold and drives the cutting tools.
  • The face of the spindle that lies near to the table has an internal taper machined on it.

8. Over  Arm

  • It is a horizontal beam which present at the top face of the column.
  • This may be a single casting which slides on the top face of the column.
  • It might comprise of a couple of tube shaped bars that slide through the openings in the segment.

9. Arbor

  • The arbor has an oil reservoir that lubricates the the bearing surfaces.
  • It prevents the spring of outer end of the arbor during cutting operations.
  • Arbor also helps in aligning the outer end of the arbor with the spindle.

10. Ram

  • The smash on which the processing head is connected can be situated ahead and in reverse along the slide route on the highest point of the section.

Operation of Milling Machine

  • The different milling operations are as follows:

 

1. Face milling

  • This is an operation for producing a flat surface, which is perpendicular to the axis of rotating cutter.

Face_Milling

  • The operation is perform by the face milling cutter.

2. Plain milling

  • It is the operation of production of a plain, flat, horizontal surface parallel to the axis of rotation.

Plain_Milling_Operation

 

  • It is also call as slab or surface milling. 
  • A plain milling cutter is use.

3. End milling

  • It is the operation of production of flat surface which may be vertical, horizontal or at an angle in reference to the table surface.

End Milling Operation

  • End mill cutter is use.
  • There cutters are using for production of slots, grooves or key ways.

4. Side milling

  • It is the machining process which produces flat vertical surface at the sides of a work piece.

5. Slot milling

  • This is a operation of producing slots like T– slots, Plain- slots etc.

6. Angular milling

Angular_Milling

  • It is the operation of producing all types of angular cuts like V- notches, grooves, serrations and angular surfaces.
  • E.g. Production of V- Blocks, etc.

7. Form milling

  • This is the process of machining special contour ( outline ) composed of curves, straight lines, or entirely of curves at a single cut.

Form_Milling_Operation

 

  • This operation is accomplish by using convex, concave and corner rounding milling cutters.
  • In the wake of machining, the shaped surface is checked by a layout measure.

8. Straddle milling

  • It is a process in which two side cutters are use to machining two opposite sides of a work piece simultaneously.

Straddle_Milling_Operation

  • The Straddle milling is very common to produce square or hexagonal surfaces.

9. Gang milling

Gang_Milling_Operation

  • It is the machining process in which two or more milling cutters are use together to perform different operations simultaneously.

10. Profile milling

Profile_Milling_Operation

  • It is the operation of reproduction of an outline of a template or complex shape of a master die on a work piece.

11. Saw milling

Saw_Milling_Operation

  • The Saw milling is the operation of production of a narrow slots or grooves on a work piece by using a saw milling cutter.

12. Gear milling

  • The gear cutting operation is performed in a milling machine by using a form relieved cutter.
  • The cutter may be cylindrical type or end mill type. The cutter profile corresponds exactly with the tooth space of the gear.

Gear_Cutting_Milling_Operation

  • Similarly separated rigging teeth are cut on an apparatus clear by holding the work on an all inclusive isolating head and afterward ordering it.

13. Helical milling

  • The helical milling is the operation of production of helical flutes or grooves around the periphery of a cylindrical or conical work piece.

Milling ( Machine ) | Definition, Parts, Operations, Types, and Methods

  • The usual examples of work performed by helical milling operations are : Production of helical milling cutters, helical gears, cutting helical grooves or flutes on a drill blank or a reamer.

14. Cam milling

  • The Cam milling is the operation of production of cams in a milling machine by the use of a universal dividing head and a vertical milling attachment.
  • The axis of the cam can be set from zero to ninety degrees in reference to the surface of the table for obtaining different rise of the cam.
  • The cams are used to open and close of valves in the internal combustion engines.

15. Thread milling

  • The thread milling is operation of production of threads by using a single or multiple threads milling cutter.

Thread_Milling_Operation

  • The operation is performed in special thread milling machines to produce accurate threads in small or large quantities.

Types of Milling Machine

  • According to their general design classification of milling machine are:

1. Column and knee type

   a. Hand milling machine

   b. Plain ( Horizontal ) milling machine

   c. Universal milling machine

   d. Omniversal milling machine

   e. Vertical milling machine

2. Manufacturing of fixed bed type

  a. Simplex milling machine

  b. Duplex milling machine

  c. Triplex milling machine 

3. Planer type

4. Special type

  a. Rotary table milling machine

  b. Drum milling machine

  c. Planetary milling machine

  d. Pantograph, Profiling & Tracer controlled milling machine

1. Column and knee type

Column and knee type Milling Machine

Source: engineersgallery.com

  • It is most commonly used in general shop-work.
  • The column and knee type milling machine are classified according to the various methods of supplying power to the table, different movements of the table and different axis of rotation of the main spindle.
a. Hand milling machine
  • In Hand milling, the feeding movement of the table is supplie by hand power.
  • The machine is relatively smaller in size than that of other types and is particularly suitable for light and simple milling operations such as machining slots, grooves, and key ways.
 b. Plain ( Horizontal ) milling machine
  • It is the simplest form of milling machine.
  • In this milling, the work piece can be fed in all three axes and this process is suitable for short production.
  • In this milling heavy work piece cannot machined and the operation is slow because of large number of controls.
c. Universal milling machine
  • It is similar to the horizontal milling but the table is placed on the swivel and swivel is placed on the saddle.
  • The machine can be produce spur, spiral, bevel gears, twist drills, reamers, milling cutters, etc. besides doing all conventional milling operations.
d. Omniversal milling machine
  • In this machine, all the movements of a universal milling machine, can be tilted in a vertical plane by providing a swivel arrangement at the knee besides the table.
e. Vertical milling machine
  • In this machine, cutter spindle have vertical position and the table movements are horizontal, vertical and transverse.
  • In vertical milling, over arm is small and provides a strong support for the spindle and spindle can be moves up and down to perform the operations like grooving, facing etc.

2. Manufacturing of fixed bed type

  • The fixed bed type milling are comparatively large, heavy, and rigid and differ radically from column and knee type by the construction of  its table mounting.
  • The table movement is restricted to reciprocation at right angles to the spindle axis with no provision for cross or vertical adjustment.
  • The shaper mounted on the axle head might be moved vertically on the section, and the axle might be balanced on a level plane.

a. Simplex milling machine

Simplex milling machine

Source: mte.us.com

  • In the simplex machine, the spindle head or the spindle can travel only in one direction.
  • Mostly, it travels in vertical direction.

b. Duplex milling machine

Duplex Milling Machine

Image Source: Indiamart.com

  • In this machine, the shaft can travel both vertical and flat way.

c. Triplex milling machine

  • In triplex machine, the spindle can move in all three direction along X, Y and Z, axis.

3. Planer type

  • It’s mostly use for facing operation in mass production.
  • These machine is similar to the bed type milling except it can mounted with various cutters and spindle heads to the machine.

Planer type Milling Machine

Source: Indiamart.com

  • These cutters can perform the facing operations simultaneously.

4. Special type

  • These machines are the modern milling machines which are developed to easy the milling operations according to the job.
  • Following are the special type of milling machines are:
a. Rotary table milling machine
  • This is the modification of a vertical machine for the machining of flat surfaces at production rate.
  • The cutter may be set at different heights relative to the work so that when one of the cutter is roughing the pieces, the other is finishing them.

b. Drum milling machine

  • It’s use for production work only.
  • This type of machine has a vertical central drum which rotates on a horizontal axis much like a Ferry’s wheel.
  • In activity, the drum – apparatus turns gradually, conveying the neutralize the pivoting cutters.

c. Planetary milling machine

  • In this machine, the work is held stationary while the cutters move in a planetary path to finish a cylindrical surface on the work either internally or externally or simultaneously.

d. Pantograph, Profiling & Tracer controlled milling machine

  • Pantograph
  • A pantograph is a mechanism that is generally constructed of four bars or links which are joined in the form of a parallelogram.

Pantograph Milling Machine

Image Source: Indiamart.com

  • It twists so as to enable a client to draw a picture while at the same time drawing at least two duplicates of it..
  • Profiling
  • A profiling machine duplicates the full size of the template attached to the machine.
  • This is practically a vertical milling machine of bed type in which the spindle can be adjusted vertically and the cutter head horizontally across the table.
  • The movement of the cutter is regulated by a hardened guide pin.
  • Tracer controlled
  • The tracer controlled milling machine reproduces irregular or complex shapes of dies, moulds, etc, by synchronized movements of the cutter and tracing element.

Methods of Milling Machine

 

Two basic methods of millings are :

 1. Up milling or conventional milling

 2. Down milling or climb milling

 

1. Up milling or conventional milling

Up_milling

  • The Up milling is also call as conventional milling.
  • In an Up milling process, the direction of cutter rotation is opposite to that of feed motion.
  • If cutter rotates clockwise, the feed motion will take place in rightward direction.
  • The chip thickness is least toward the beginning of the cut and most extreme toward the end.
  • Slicing power shifts from zero to the most extreme worth.

Advantages of Up milling

  • The cutter is not affected by the sandy surfaces of the work piece.
  • It doesn’t require backlash eliminator.
  • Built up edge ( BUE ) fragments are not available on the machining surface.
  • The loads on the teeth are acting gradually.

Disadvantages

  • The propensity of slicing power to lift the work from the installations and poor surface completion.

2. Down milling or climb milling

Down_milling

  • It is also know as climb milling.
  • In down milling, the work piece cuts from right to left cutter rotation in clockwise direction.
  • The chip thickness is maximum at the start of the cut and minimum in the end.
  • There is less friction involves and consequently less heat is generated on the contact surface of the cutter and work piece.

Advantages

  • Tool blunting is less.
  • It produces better surface finish.
  • The flat work piece can be machining easily.
  • It is characterized by less tendencies of chattering and vibration.
  • The fixture are simple and less costly.

Disadvantages

  • The chip thickness is maximum at the point of tooth contact with the work piece.

Difference between Up milling & Down milling

S.NO.

Up Milling

Down Milling

1.

It is also known as conventional milling. It is also known as climb milling.

2.

In this milling, the cutter rotates against direction of feed. In this milling, the cutter rotates with direction of feed.

3.

The width size of the chip is zero at initial cut and increase with feed. This will maximum at the end of feed. The size of the chip is maximum at start of cut and decrease with the feed. This will zero at the end of feed.

4.

The tool wear rate is more because tool runs against the feed. The tool wear rate is less because the cutter rotates with feed.

5.

The cutting chips fall down in front of the cutting tool. The cutting chips fall down behind the tool.

6.

It gives less surface finish.  It gives better surface finish.
7. The cutting chips are carried upward with the help of tool. The cutting chips are carried downward with the help of the tool.
8. The heat is diffuse to the work piece which causes the change in metal properties. The heat is diffuse to the chip does not change the work piece properties.
9. Tool life is less. Tool life is more.
10. This is also famous as traditional way of cutting the surface. This is non – traditional way of cutting the work piece.
11. The high quality cutting fluid is used. The simple cutting fluid is used.
12. Because of upward force by tool, high strength jig and fixture are used. Because of downward force by tool, normal jig and fixture are used.
13. It requires high cutting force. It requires low cutting force.
14. The cutting forces act upward. The cutting forces act downward.
15. It is mostly applicable for cutting of brass, bronze and ferrous materials. It is mostly applicable for aluminium and aluminium alloys.

Types of Milling cutters

  • A milling cutter is a cutting tool of milling machine, which are available in many shapes and standards.
  • The teeth may be straight or at a helix angle and helix angle helps milling cutter for a slow engagement of the tool to distribute the forces.

         There are wide ranges of milling cutters;

1. Plain cutters

2. End mills

3. Face mill

4. Slab mill

5. Hollow mills 

6. Metal slitting saws

7. Side and face cutter 

8. Cylindrical side and face slotting, screw slotting

9. Single, double and equal angle cutters

10. T -slot, dovetail, convex, single and double corner rounding cutters

 

1. Plain cutters

  • These mills are use to cut with the sides only.

Plain cutters

  • They have straight or helical teeth.

2. End mills

  • End mills are generally HSS cutting tools with three or more flutes.
  • They are intended for bulk metal removal with their flutes and unless they are only suitable for side cutting.

End mills

  • Early end mills and most large end mills have a recessed center at each end of the cutter to facilitate resharpening.

3. Face mill

  • A face mill consist of a cutter body that is designed to hold multiple disposable carbide or ceramic tips.

Face mill

  • These tips may be rotates within the holder to present a fresh face to the work piece, this increases the life of the tip and thus their economical cutting life.

4. Slab mill

  • Slab mills are using in horizontal or universal milling machines to machine large broad surfaces quickly.

Slab mill

  • They have been superseded by the use of carbide tipped face mills that are then used in vertical mills or machining centers.

5. Hollow mills

  • These cutters are use in the screw machines.

Hollow mills

  • In the hollow mills, the cutting teethes are available inside of the surfaces.

6. Metal slitting saws

  • A metal slitting saw is similar to a circular saw blade.
  • It is mostly use for deep slotting and sinking in cuts.

7. Side and face cutter

  • The side and face cutter having cutting teeth on its side as well as its circumference.

Side and face cutter

  • The teeth on the side allow the cutter to make unbalanced cuts without deflecting the cutter as would happen with a slitting saw or slot cutter.

8. Cylindrical side and face slotting, screw slotting

  • Slot drills are generally two fluted cutters that are designed to cut on their end as well as the flutes.
  • For this kind of cutters, slot drills, one of their frontal cutting edges should be across the center for drilling function.

9. Single, double and equal angle cutters

  • Single angle cutters ( Double and equal angle cutters ) are those which have teeth on the conical or angular face of the cutter and having large flat side.
  • Double or equal angle cutter have V -shaped teeth with both conical surfaces at an angle to their end faces.
  • They are commonly use for cutting various kinds of metals.

10. T -slot, dovetail, convex, single and double corner rounding cutters

Milling ( Machine ) | Definition, Parts, Operations, Types, and Methods

  • A dovetail cutter form leaves behind a dovetail slot.

 

Lubricant

  • In the Roman era, lubricants had been based on oil and rapeseed oil, as well as animal fats.
  • It is the life – blood of the machine, keeping the vital parts in perfect condition and prolonging the life of machine.
  • It saves the machine and its parts from corrosion, wear and tear and it minimizes friction.

Definition of Lubricant

  • A lubricant is a substance having an oily property available in the form of fluid, semi – fluid or solid state.

                               or

  • A lubricant is substance introduced between two mating parts to reduce friction.

Lubricant

Image: Lubricant

Purposes of Lubricant

  • It improves the machine efficiency.
  • It prevents corrosion, wear and tear.
  • This reduces friction.
  • It cools the moving elements.
  • It aids in distributing the load.

Properties of Lubricant

The properties of lubricants are as follows:

 1. Oiliness

 2. Viscosity

 3. Flash Point

 4. Fire Point

 5. Pour Point

 6. Emulsification

 7. Acidity

 8. Oxidation

 9. Votarility

 10. Specific Gravity

 11. Carbon Residue Contents

 

 1. Oiliness

  • The oiliness term relates to a lubricant tendency to wet and adhere to a surface in which thin layer of oil film is formed in between two moving parts. So, surface remains oily.

2. Viscosity

  • The viscosity is a measurement of the internal resistance of a lubricant i.e., heavy oil has high viscosity and light oil has low viscosity.
  • It’s indicate the viscosity of lubricant by numbers such as SAF -30, SAF -40 etc.

 3. Flash Point

  • The flash point is the temperature at which , a lubricant converts into steam.

4. Fire Point

  • It is a temperature point at which oil or lubricant tends to the vapourising i.e., 15 to 25° C. Each oil or lubricants have a separate fire and flash point.
  • It should be less than the working temperature of bearing.

5. Pour Point

  • The pour point of a lubricants are the lowest temperature at which, an oil will flow from its container.
  • At low temperature, the viscosity of the oil forms wax crystals. These crystals can clog filters and small openings.

6. Emulsification

  • The emulsify means combining two liquids together which normally do not mix. So, when oil comes contact with water, this is term as emulsification, e.g., steam engine, steam turbine, hydraulic turbine, etc.

7. Acidity

  • In greases, causticity indicates the nearness of corrosive sort constituents whose focus is typically characterize as far as all out corrosive number.
  • The acidity should not be present in oil.

 8. Oxidation

  • The oxidation reduce the flow of oil when lubricant contact with hot air. This oxide formation is stop by adding in the oil.

 9. Votarility

  • It is a lubricant property that defines its evaporative loss characteristics. In this process, less emulsification of an oil else consumption is more.
  • It is the most important in high temperature applications where low viscosity oils are utilize, such as engines. Also, the most volatile a lubricant, the greater its flammability.

10. Specific Gravity

  • It is a property of an oil at which its weight compared with water at 30° F.

 11. Carbon Residue Contents

  • Carbon residue contents of any oil indicated, its capacity of lubricating and quantity of reduced contents. A good lubricant has negligible carbon residue contents.
  • For an engine in combustion and com-pressure process, its quantity should be negligible.

Types of Lubricant

  Normally, lubricants are classified into three groups such as 

 

   1. Liquid Lubricants

                a. Mineral oil

                b. Organic oil

                c. Synthetic oil

                d. Blended oil 

 2. Solid Lubricants

 3. Semi – solid Lubricants

 

1. Liquid Lubricants

  • It is available in liquid form such as mobile oil, spindle oil, natural oils, mineral oils, semi solid lubricants, liquid lubricants.

 There are four types of liquid lubricants as follows.

  a. Mineral oil

  •  It is a substance which comes from petroleum. These oils contain the paraffine and naphthanic quantity, i.e., stable with the high temperature.
  • E.g., Circulating oil, gear oil, machine or engine oil, refrigeration grade oil, steam cylinder oil and wire rope oil.

  b. Organic oil

  • It is a substance which comes from the animals, vegetables and fishes. It is conducted the alcohols and fat acids.
  • Due to these components, it has an oxide property in the coagulation at the low temperature for the coagulation at the low temperature. 
  • For the heavy load, it is mixed with the mineral oil. It is also term as the compound oil.

  c. Synthetic oil

  • It is substance comes from the polakaline glycols, silicons and silicon carbide.
  • In the refinery, silicon carbide converts into silicon and oxygen and mixed with another elements / metals, got the silicon lubricant.
  • These oils having continuous long life its qualities. So that, it is used to the precision tools.

  d. Blended oil  

  • To make the heavy lubricant and increasing the viscosity, the fatty oil 5 to 20 % is used. It is called compound oil or blended oil. 

 

  2. Solid Lubricants

  • Solid lubricantion is simply the lubricantion of two surfaces in moving contact by means of solid materials interposed between them without the need for a liquid medium.
  • The vast majorities of solid lubricant applications are met by only some materials – graphite, molybdenum, disulphide, and PTFE ( Polytera Fluoro Ethylene ), wax, tallac, etc. 

 

  3. Semi – solid Lubricants

  • It is obtained by get – like texture of lubricating oil by the addition of metallic. These lubricants are called grease.
  • So, it is prepared by saponification  of vegetable oils or fats with alkali such as thickener or gelling agents.
  • Grease is used to describe lubricating materials i.e., simply soft solids, high viscosity liquids.     

 

   Selection of Lubricants

        The selection of any lubricant depends upon the following terms:

       i. On the pressure at the both surfaces area.

      ii. On the clearance between the bush and shaft.

      iii. On the motion of relative to the both surfaces.

      iv. On the working temperature.

 

Methods of Lubrication

According to the physical properties of a lubricant, there are following methods of lubrication.                 

 1. Gravity Feed

    i. Oil Cup

   ii. Wick Lubricator

   iii. Drip Feed Lubricator

   iv. Lieuvain’s Glass Bottle Lubricator

 2. Force feed

   i. Oil, Grease Gun and Grease Cups

   ii. Pressure Feed by Hand Pump

  iii. Oil Pump Method

 3. Splash lubrication

 

1. Gravity Feed
  • In this process, oil is filled in the bottle and placed high to the machine and used to drop by drop with the help of cotton.
  • In this process, following methods are used:

  i. Oil Cup

  • This is an ordinary cup shape lubricator. It is fitted with oil vent by using the threads.

Lubricant | Definition, Types, Purposes, Properties, Selection, Methods

  • It safeguards the oil vent and oil for the dusting and supply the oil or lubricant continuously.

 ii. Wick Lubricator

  • Its working principle depends upon the siphon.
  • In this lubricator, having a work i.e., one end full filled in the oil cup and second end connected the lubricated part of machine.

Wick Lubricator

  • In this process, the oil bellowed in the wick as shown in fig.

 iii. Drip Feed Lubricator

  • It has a oil reservoir made by glass as shown in fig. It has a hole in head, called filling hole.

Drip Feed Lubricator

  • This is used for filling oil in the reservoir. The oil entered in the chamber after filtered and felled drop by drop due to gravitation force.

 iv. Lieuvain’s Glass Bottle Lubricator

  • It is made from glass, full of oil as shown in fig.
  • It has fitted a double tapered cork in its mouth with a center head fitted needle. So, it is also term as needle lubricator.

Lieuvain's Glass Bottle Lubricator

  • It is fitted with the oil vent due to its stopper or cork. In this process, the shaft is rotated and lubricant applying in machine.
 2. Force feed
  • It is a process of feeding the lubricant or coolant in any machine by the manual or machinery force.
  • There are following some methods of force feed processing:

i. Oil, Grease Gun and Grease Cups

  • The oil hole or grease point leading to each bearing, is fitted with a nipple and pressing the nose of gun against this, the lubricant is forced to the bearing.

Grease Cup and Grease Gun

  • Greases are also force feed using grease cup. Grease cup is also term as  hand – pressure grease staufier. It is made up of brass or cast iron.

 ii. Pressure Feed by Hand Pump

  • Oil is also pressure feed by hand pump and a charge of oil is delivered to each bearing at intervals once or twice a day by operating a lever provided with some machines.

Pressure Feed by Hand Pump

  • This is also know as shot lubricator.

 iii. Oil Pump Method

  • In this method, an oil pump driven by the machine delivers oil to the bearings continuously and the oil afterwards drains from the bearing to a pump from which, it drawn by the pump again for lubrication.

Lubricant | Definition, Types, Purposes, Properties, Selection, Methods

3. Splash lubrication
  • In this method, a ring oilier attached to the shaft and it dips into the oil and a stream of lubricant continuously splashes around the parts as the shaft rotates.

 

  • The rotation of the shaft causes the ring to turn and the oil adhering to it brought up and fed into the bearing and the oil is then led back into the reservoir. This is also know as  ring oiling.

Lubricant | Definition, Types, Purposes, Properties, Selection, Methods

  • In other systems (such as chain oilier, worm gear bath oilier, etc ) , one of the rotating elements comes in the contact with that of the oil level and splash the whole system with lubricating oil while working.
  • Such systems can be found in the headstock of a lathe machine and an oil engine cylinder.

 

  • As the lubrication of machine is one of the important factor to increase the life span of a machine, cooling is also essential to run the machine and its parts at proper working condition and avoid the wearing out of parts due to heating.

Advantages of Lubricant

  • It’s increase the working capacity of machine.
  • It reduces the heat produced due to friction.
  • Lubricant increases the life of energy.
  • It protects the machine from rust.
  • It carry away contaminant debris.
  • Lubricant helps to machine run fast and smoothly.

Disadvantages of Lubricant

  • Coefficient of friction is high.
  • Self healing property is poor.
  • Poor heat dissipation. For e.g., Polymers etc.
  • Some lubricants is the production of oil spots. For e.g., Steric acid, Salts, and derivatives.

Mechanism of Lubricant

  • There are mainly two types of mechanics:

Also readhttps://mechanicalnotes.com/fluid-definition-fluid-mechanics-classification-properties-and-difference/

 1. Fluid Lubrication

 2. Boundary Lubrication

1. Fluid Lubrication

  • In this type of lubrication is utilize in those cases where liquid lubricants having minimum viscosity under working conditions.

 2. Boundary Lubrication

  • It happens when

                        A shaft starts moving from rest.

                        The speed is very low.

                         The load is very high.

                         Viscosity of this lubricant is too high.

 

Fluid

  • In like manner utilization, ‘ Fluid ‘is often used as a synonym for “ liquid “, with no implication that gas could also be present.

Definition of fluid

  •  It may be defined as follows:
  • A fluid is a substance which is equipped for streaming.

                                                   or

  • A fluid is a substance which disfigures persistently when exposed to outside shearing power.

Fluid

 Image. Fluids

 

Behavior of Fluids

  •  The analysis of fluids behavior is based on:

                i. Fundamental laws of mechanics

               ii. Conservation of mass momentum energy and

               iv. Laws of thermodynamics

Fluid Mechanics

  • Mechanics is the most seasoned physical science that manages both stationary and moving bodies affected by powers.
  • The subcategory fluid mechanics may be defined as that branch of Engineering science which deals with the behaviour of fluids under the conditions of rest and motion.
  • It includes liquids, gases, plasmas and , to some an extent plastics solids.
  • They may be divided into three parts:

          1. Statics                   2. Kinematics                    3. Dynamics

1. Statics

  • The study of in -compressible fluids under static conditions is called hydro statics and that dealing with the compressible static gases is termed as aerostatics.

2. Kinematics

  • It manages the speeds, increasing velocities and the examples of stream as it were.

3. Dynamics

  • It deals with the relations between velocities, accelerations of fluids with the forces or energy causing them.

Application areas of fluid Mechanics

  • Mechanics of liquids is critical in numerous territories of building and science. Examples are:

            

     i. Biomechanics

  • Blood flow through arteries and veins
  • Air flow in the lungs
  • Flow of cerebral fluids

     ii. Households

  • Funneling frameworks for cold water, petroleum gas, and sewage.
  • Piping and ducting network of heating and air – conditioning system.

     iii. Meteorology and Ocean Engineering

  • Movements of air currents and water currents.

     iv. Mechanical Engineering

  • Plan of siphons, turbines, air – molding hardware, contamination – control gear, and so forth.

     v. Civil Engineering

  • Transport of river sediments
  • Pollution of air and water
  • Flood control systems

     vi. Automobile

  • IC motor, cooling, fuel stream, outside optimal design, and so on.

 

Classification of Fluid

  •  The fluids can be classified as follows:

    1. Ideal Fluid 

   2. Real Fluid

   3. Newtonian Fluid 

   4. Non -Newtonian Fluid

    5. Ideal Plastic Fluid 

Stress- Strain Graphs of Different Types of Fluid

                                                   Stress- Strain Graphs of Different Types of Fluid

1. Ideal Fluid

  • The liquids which are incompressible and is having no thickness is known as a perfect liquid.
  • A perfect liquid is just a nonexistent liquid as every one of the liquids which exist, have some thickness.

2. Real Fluid

  • The fluids, which possesses viscosity is known as real fluid.
  • Every one of the liquids, in genuine practice, are genuine liquids.

3. Newtonian Fluids

  •  A real fluids in which the shear stress is directly proportional to the rate of shear strain ( or velocity gradient ) known as a Newtonian Fluids.

4. Non – Newtonian Fluids 

  • A real fluids in which the shear stress is not proportional to the rate of shear strain ( or velocity gradient ) known as a Non – Newtonian Fluids.

 

                                 Ω yx  du / dy ]=0

 There are mainly two types of  Non – Newtonian Fluids

  1. Time independent                                                  

    a. Pseudo Plastic                                                                      

    b. Dilatent fluid

    c. Ideal Bingham

 2. Time dependent

      a.Thixotropic

    b. Rheopectic 

Graph of Non-Newtonian fluid

                             Graph. Non- Newtonian Fluid

 1. Time independent   

 a. Pseudo Plastic

  • Pseudo plastic is the higher velocity gradients where the shearing force increases less than proportionally, i.e n < 1 as shown in graph.
  • The phenomena of under the influence of movement, the liquid seems to become thinner. Subsequently, it is known as ” Shear diminishing “.
  • For example: Blood, milk etc.

b. Dilatent fluid

  • In Dilatent, the viscosity of fluids will grow with the rate of shear strain. Here n > 1 and B = 0.
  • It is additionally term as ” shear thickening “. For example: Butter solution, sugar solution, rice starch solution etc.

c. Ideal Bingham

  • It has some underlying quality past which miss happening begins.
  • For example : Tooth paste, creams, sewage sludge etc.

2. Time dependent

    a.Thixotropic

  • In Thixotropic, fluids which take a finite time to attain equilibrium  viscosity when introduced to a steep change shear rate ( n< 1 & B ≠ 0 ).
  • They are reversible changes from fluid to solid – like elastic gel.
  • Example ; Paints, Printing inks, Gel etc.

  b. Rheopectic

  • μ increases with time for which shearing forces are applied.
  • Here n > 1 & B ≠ 0. Examples – Gypsum paste and Bentonite solution etc.

 

 5. Ideal Plastic Fluids 

  • The fluids in which shear stress is more than the yield value and shear stress is proportional to the rate of shear strain ( or velocity gradientis known as ideal plastic fluids.

Also read: https://mechanicalnotes.com/lubricant-definition-types-purposes-properties-selection-methods/

  • The material properties of a fluid, which may vary, sometimes sensitively with temperature, pressure and composition, determine its mechanical behaviour.

  Properties of fluids

 1. Density

 2. Specific weight                                                       

 3. Specific gravity or Relative Density

4. Specific volume                

  1. Density

  • The mass per unity volume is known as density.
  • It is usually denoted by rho ( Ρ ). It’s units are kg/m³, i.e.,

                                                       ρ = m / V

 2. Specific weight

  • It is defined as the weight per unity volume.
  • It is usually denoted by w.

3. Specific gravity or Relative Density

  • Specific gravity ( Relative Density )  is the ratio of specific weight of liquid to specific weight of a standard fluids.
  • It is dimensionless and has no units. It is represented by S.

4. Specific volume

  • It is defined as volume per unity mass of liquid.
  • It is denoted by ν.

                                          ν = V / m  or 1 / ρ

Difference between Fluid and Liquid

S.NO. Fluid Liquid
1. It is a condition specific to certain substances or it is a subset of matter. Liquid is  one  of the three phases or state of matter.
2. Fluids flow and has some viscosity (thickness). Fluids additionally streams and it has volume, yet no distinct shape.
3. Fluids include liquids. All liquids are fluids.
4. It is a substance that lacks rigidity. it cannot resist force when it is applied to it. Liquids can assume the shape of any container or vessel and they are relatively in-compressible.

Introduction

 

  • The concrete is made with concrete wastes which are Eco – friendly so called as Green concrete.The other name for green concrete is resource saving structures with reduced environmental impact, For e.g. Energy saving, CO2 emissions, waste water. Green concrete is a revolutionary topic in the history of concrete industry. This was first invented in Denmark in the year 1998 by Dr. WG.

 

                                                                    Green Concrete || Introduction, Materials, Types, Advantages, Limitations

  • Green Concrete is a concrete building material that decreases impact on environment which does not contribute CO2 emission and decrease of corrosion and heat cracking. Green Concrete is a term give to a concrete that has extra steps taken in the mix design and placement to insure a sustainable structure and a long life cycle with a low maintenance surface.

 

  • It is made from a combination of an inorganic polymer and between 25% and 100% industrial waste. It gains strength faster and has a lower rate of shrinkage than concrete made only from Portland Cement. Structures built using green concrete have a better chance of sustaining a fire, as it can withstand temperatures of up to 2400° F. Structure constructed from it is more resistant to temperature changes, thus saving heating and cooling costs.

 

          Features of Green Concrete

Cycle of Green Concrete

                                                                         Fig.2 Cycle Process

  • Better Performance                                                                 
  • Enhance cohesion work ability / consistency
  • Reduce shrinkage / creep.
  • Durability – Better service life of concrete
  • Reduce carbon footprint
  • Optimizes use of available materials
  • No increase in cost
  • LID India Certification                                                                                                                                                        

    Materials for Green Concrete

  • Green construction materials compose of renewable things. Green materials are environmentally responsible because impacts are consider over the life of the product. Depending  upon project – specific goals, green materials may involve an evaluation of  one or more of the following criteria.

     1. Locally available                                                                      

    2. Salvaged, re – furnished, or re – manufactured

    3. Reusable or recyclable

Coarse Aggregat

                                                                             Fig.3  Coarse Aggregate

Fine Aggreggate

                                                                             Fig.4  Fine Aggregate

Cementitious materials – Fly Ash

  • Fly ash is a by -product, produced during the operation of coal -fired power  plants. The finely divided particles from the exhaust gases are collected in  electrostatic precipitators. These particles are called as Fly ash.

Fly Ash

  • Advantages Of Using Fly Ash in Concrete:

1. Utilization of fly ash as a part replacement of cement or as a mineral admixture in concrete saves on cement and hence the emission of  CO2.

2.  Use of good quality of fly ash in concrete has shown remarkable improvement in durability of concrete, especially in aggressive environment.

3. Some of the technical benefits of the use of fly ash in Green Concrete are:-

a) Higher ultimate strength

b) Increase durability

c) Improve work-ability

d) Reduce bleeding

e) Increase resistance to alkali-silica reactivity.

f) Reduce shrinkage. 

Suitability of Green Concretes in Structures

 1. Reduce the dead weight of a structure and reduce crane age load; allow handling, lifting flexibility with lighter weight.

 2. Good thermal and fire resistance, sound insulation than the traditional  granite rock.

 3. It improves damping resistance of building.

 4. Reduction of the concrete industry’s CO2 emission by 30 %.

 5. Increase concrete industry’s use of waste products by 20%.

 6. No environmental pollution and sustainable development.

 7. It’s require less maintenance and repairs.

 8. Compressive strength behavior of concrete with water cement ratio is  more than that of conventional concrete.

 9. Flexural strength of green concrete is almost equal to that of conventional concrete.

Scope of Green Concrete

  • They having a revolutionary topic in the history of concrete industry. As green concrete is made with concrete wastes it does take more time to come in India because of industries having problem to dispose wastes and it also reduces environmental impact with reduction in CO2 emission.

 

  • Use of green concrete can help us to reduce a lot of wastage of several products. Various non-biodegradable products can also be used and thus avoiding the issues of their disposal.

Types of Concrete

Also read : Cement Chapter

1. Reinforced Cement Concrete

2. Plain Cement Concrete

3. Ready -mix Concrete

4. Light weight Concrete

5. Fiber reinforced Concrete

6. Green Concrete

1. Reinforced Cement Concrete ( R C C )

Green Concrete || Introduction, Materials, Types, Advantages, Limitations

  • It is the combination of ordinary concrete with the steel to increase its compressive and tensile strength to a great extent.
  • Widely use of this in the construction field.
  • It reduces the size of structure.
  • Sizes reduce but load bearing capacity increases.
  • So, Today’s world likes this most.
  • It saves money due to reduce size of structure.
  • In old age, due to no use of R C C, size of place increase and also takes wide area for making place.
  • For example :-

                    a. Buildings

                    b. Flyover

                    c. Highways roads traffic

                    d. Hydro -power plants

                    e. Tunnels

                    f. Irrigation canals

                    g. Drains ,etc.  

2. Plain Cement Concrete ( P C C )

PCC

 

  • It is the mixture of cement, fine aggregate, and coarse aggregate without steel.
  • It is popularly known as P C C.
  • Before starting any R C C work on ground, we first do P C C work to stop corrosion of steel.
  • Save main structure from bacterial attack.

3. Ready -mix Concrete

RMC

 

  • It never prepares on the job site.
  • This prepares at central plant on a fixed batch.
  • It is fully machinery made mix.
  • Making construction work of this is on huge scale.

4. Light weight Concrete

LWC

 

  • It is a type of mixture that is made with a light weight coarse aggregate and five aggregate which may be light weight.
  • It oftens used in house construction.
  • Reduction in dead loads making savings in foundations and reinforcement.
  • Improved thermal properties.
  • Improved fore resistances.
  • Reduction in form work.

5. Fiber reinforced Concrete

FRC

 

  • It is a mixture of cement, mortar or concrete with suitable fibers.
  • Increases the tensile strength of the concrete.
  • Reduces the air voids & water voids.
  • This increases the durability of the concrete.
  • It’s compressive strength is not enough.
  • It does not prefer for heavy structure.

6. Green Concrete

  • I have already discussed about it above.

Environmental Benefits to using Green Concrete

  • Geo- polymer concrete, or green concrete, is part of a movement to create construction materials that having a reduction impact on the environment. It is made from a combination of an inorganic polymer and 25 to 100 percent industrial waste.

             Here is a list of 4 benefits to using green concrete.

     1. Lasts Longer

  • Green concrete gains strength faster and has a lower rate of shrinkage than concrete made up of Portland Cement.
  • Structures build using green concrete have a better chance of surve a fire ( it can withstand temperatures of up to 2400 degrees on the Fahrenheit scale ). It also has a greater resistance to corrosion which is important with the effect of pollution has on the environment ( acid rain greatly reduces the longevity of traditional building materials ).

 

  • All of those factors add up to a building that will last much longer than one made with ordinary concrete. Similar concrete mixtures have been found in ancient Roman structures and this material was also used in the Ukraine in the 1950 and 1960.

 

  • Over 40 years later those Ukrainian buildings are still standing. If buildings don’t have to be rebuilt, fewer construction materials have needed and the impact to the environment is reduced.

 

  2. Uses Industrial Waste

  • Instead of a 100 percent Portland cement mixture, green concrete uses 25 to 100 percent fly ash. Fly ash is a byproduct of coal combustion and is gathered from the chimneys of industrial plants ( such as power plants ) that use coal as a power source.

 

  • Hundreds of thousands of acres of land are used to dispose of fly ash. A large increase in the use of green concrete in construction will provide a way to use up fly ash and hopefully free many acres of land. 

   3. Reduces Energy Consumption

  • If you use less Portland cement and more fly ash when mixing concrete, then you will use less energy. The materials use in Portland cement require huge amounts of coal or natural gas to heat it up to the appropriate temperature to turn them into Portland cement.

 

  • Fly ash already exists as a byproduct of another industrial process so you are not expending much more energy to use it to create green concrete. Another way that green concrete reduces energy consumption is that a building construct from it is more resistant to temperature changes.
  • An architect can use this and design a green concrete building to use energy for heating and cooling more efficiently. 

  4. Reduces CO2 Emissions

  • In order to make Portland cement – one of the main ingredients in ordinary cement – pulverized limestone, clay, and sand are heated to 1450 degrees C using natural gas or coal as a fuel. This process is responsible for 5 to 8 percent of all carbon dioxide ( CO2 ) emissions worldwide.
  • The manufacturing of green concrete releases has up to 80 percent fewer CO2 emissions. As a part of a global effort to reduce emissions, switching over completely to using green concrete for construction will help considerably.

Production of Green Concrete

 

  • Concrete with inorganic residual products. Ceramic wastes use as green aggregates. By replacing cement with fly ash, micro silica in larger amounts.To develop new green cements and binding materials ( i.e. by increasing the use of alternative raw materials and alternative fuels, and by developing / improving cement with low energy consumption ).

 

  • To use residual products from the concrete industry, i.e. stone dust ( from crushing of aggregate ) and concrete slurry ( from washing of mixers and other equipment ). To use new types of cement with reduced environmental impact. ( mineralized cement, limestone addition, waste – derived fuels ).

Green Lightweight Aggregates

 

  • Synthetic lightweight aggregate produces from environmental waste is a viable new source of structural aggregate material. The uses of structural grade lightweight concrete reduce considerably the self -load of a structure and permit larger precast units to be handled.

 

  • Water absorption of the green aggregate is large but the crushing strength of the resulting concrete can be high. The 28 days cube compressive strength of the resulting lightweight aggregate concrete with density of 1590 kg/m³ and respective strength of 34 MPa. Most of normal weight aggregate of normal weight concrete is natural stone such as limestone and granite.

Advantages

  • It will give increase same particle attraction so user friendly – easier to place, compact & finish concrete. It can be seen in concrete slump.
  • Optimize mix designs mean easier handling, better consistency and easier finishing.
  • Reduction in shrinkage & creep.
  • They use local and recycled materials in concrete.
  • The  heat of  hydration of green concrete is significantly  lower  than traditional concrete.
  • This result in a lower temperature rise in large concrete pours which is a distinct advantage for green concrete.
  • It decreases wastage of materials and opens way of use of waste materials in this generation.

Deck Slab

 

Improved Engineering Properties

  • Mix can result in a reduced paste volume within the concrete structure resulting in a higher level of protection against concrete deterioration.
  • Higher strength per kilogram of cement.
  • Increase durability & lower permeability.
  • More aggregates typically mean higher Modulus of elasticity.

Limitation

  • By using stainless steel, cost of reinforcement increases.
  • Structures constructed with green concrete have less life than structures with conventional concrete.
  • Split tension of green concrete is less than that of conventional concrete.
  • Corrosion in the steel bars can also occur if the aggregates used are not free from corrosion leading agents.

Necessity to Produce Green Concrete

  • To giving a better as well as healthy environment for coming generation.
  • Making use of huge amount of bad concrete which comes from breaking of old buildings, old bridges, etc.
  • Reducing as well as decreasing, the increasing amount of CO2 gas in the environment.
  • To increase the use of conventional residual products, i.e. fly ash.
  • Using residual products from the concrete industry, i.e. stone dust ( from crushing of stones ).
  • To use residual products from other industries not traditionally used in concrete, i.e. fly ash from bio fuels and sewage sludge incineration ash.
  • To use new types of cement with reduced environmental impact. 

Conclusion

  • Green concrete have reduced environmental impact with reduction of the concrete industries CO2  omissions by 30%. They have good thermal and fire resistant. In this concrete recycling, use of waste material such as ceramic wastes and aggregates increase concrete industry waste products by 20%.

 

  • Hence, they consume less energy and becomes economical. So, the use of concrete product like green concrete in future will not only reduce the emission of CO2 in environment and environmental impact but it is also economical to produce.

For better understanding watch this video clip

     Thanks for reading. If the articles help you then spread your love and don’t forget to share it on social network’s.

      Thanks for reading. If the articles help you then spread your love and don’t forget to share it on social network’s.

      Thanks for reading. If the articles help you then spread your love and don’t forget to share it on social network’s.

      Thanks for reading. If the articles help you then spread your love and don’t forget to share it on social network’s.

      Thanks for reading. If the articles help you then spread your love and don’t forget to share it on social network’s.

Cochran Boiler

  • The Cochran boiler was founded by Cochran & Co. of Annan.
  • It is a vertical multi -rounded kettle and having various level fire tubes.
  • It is the modification of simple vertical evaporator where the heating surface has been increased by means of a number of fire tubes.
  • The productivity of this evaporator is obviously superior to the straightforward vertical heater.

Definitions of Cochran Boiler

  • Cochran Boiler is one of the best types of vertical multi- tubular boiler and has a number of horizontal fire tubes.
  • They have cylindrical shell with a dome shape top where the space is provided for steam.

Main Parts of Cochran Boiler

Cochran Boiler

Fig. Cochran Boiler line Diagram.

1. Shell

  • A shell is the main body of the boiler.
  • They having vertical axis cylindrical drum with hemispherical dome type shell at the top.
  • This hemisphere gives higher volume to increase steam capacity.

2. Grate

  • It is the stage on which the strong fuel is singed.

3. Combustion chamber

  • The consuming of fuel happens in the burning chamber.

4. Fire tubes

  • The fire tubes helps in the trading of warmth from the hot vent gases to the water.

5. Fire hole

  • It is the hole through which fuel is fire inside the furnace.

6. Furnace (Fire box)

  • Furnace is the place where combustion of all the fuel is take place.
  • It lies at the bottom of the boiler.
  • It terms as fire box.

7. Ash pit

  • It is the place where ash of the burning fuel is collected.

8. Chimney

  • The chimney is attached with the smoke box.
  • And it releases smoke into the atmosphere.

9. Fire brick lining

  • It helps in the combustion of the fuel and present in combustion chamber.

10. Man hole

  • It is a hole on the boiler shell for the purpose of either cleaning, inspection and maintenance.

11. Flue pipe

  • It is a small passage which connected with the fire box and combustion chamber.
  • The hot gases enter into the combustion chamber through the pipework.

Also read : Boiler Definition, Parts, Components , etc.

Working of Cochran boiler

  • Fuel is placed at the grate through fire hole.
  • Air comes into the combustion chamber through atmosphere.
  • Fuel is burn through fire hole.
  • Then, the hot flue gases emerge out and start flowing into hemispherical dome shaped combustion chamber.
  • This hot flue gases further moves into the fire pipes.
  • The hot flue gases inside the fire tubes exchange the heat from the hot gases to the water.
  • Due to the exchange of heat, the steam produced. And it rises upward to collect into the upper side of the shell.
  • When the required pressure generated, the flue gases goes to the chimney through fire box where it leaves to the atmosphere.
  • Hence, this process repeats and run continuously.

Features

  • In Cochran boiler, any types of fuel may be used.
  • It gives 70% to 75% of thermal efficiency with coal and oil firing.
  • It is well suitable for small capacity requirement.
  • The ratio of grate area to the heating surface area varies from 10:1 to 20:1.

Specification of the Cochran boiler

  Height 5.75 m
  Efficiency 70 – 75 %
  Shell diameter 2.75 m
  Steam capacity 3500 kg/hr (max. 4000 kg/hr)
  Working pressure 6.5 bar( max. 15 bar)
  Heating surface area 120 m

Advantages

  • It occupies less floor space.
  • Initial cost of boiler is less.
  • It is easy to operate.
  • Low initialization cost.
  • They having higher volume to area ratio.
  • Easy to clean and inspect.
  • It’s easy to transport from one place to another.

Limitations

  • Maintenance and inspection are difficult due to narrow space inside for entering.
  • They having limited pressure range.
  • Steam generation rate is low.
  • Due to it’s vertical design, high room head is required for its installation.

Different types of Mounting used in Cochran boiler

  • The Mountings are those mechanical appliances which are considered essential for operating a boiler smoothly and safety. Which are normally mounted on the outside of a heater.

The following are the important mountings of a boiler:

  1. Safety valves                               2. Fusible plug

  3. Pressure gauge                          4. Water level indicator

   5. Blow off cock                             6. Feed check valve

  7. Steam stop valve

1. Safety valves

  • It is utilized to forestall blast because of extreme inward weight.
  • Safety valves are attached on the chest of the boiler.
  • General, there are two safety valves are present on a boiler.

 2. Fusible plug

  • The function of a fusible plug is to ensure safety to the boiler from begin damaged by overheating due to water level falling very low in the boiler.

3. Pressure gauge

  • It application is to measure the pressure of the steam which is present inside the boiler.
  • It’s also present in front of the boiler.

4. Water level indicator

  • It shows the immediate degree of water that’s accessible within the steam evaporator.

5. Blow off cock 

  • It is situated at the bottom of the boiler drum.

   Purpose of Blow off cock:

  i. To empty the boiler.

 ii. To discharge the dimensions, mud and sediments.

6. Feed check valve

  • It regulates the supply of water that is pumped into the boiler by feed pump.

7. Steam stop valve

  • It is normally fitted on the most noteworthy piece of the heater with the assistance of a spine.

       The main functions are as follows:

   i. To regulate the flow of steam from the boiler to the moststeam line.

  ii. To fully shut off the steam provide.

Different types of Accessories used in Cochran boiler

1. Economizer

2. Feed pump

3. Super heater

4. Air preheater

1. Economizer

  • It improves the economy of the boilers.
  • It is used to heat the feed water by the application of heat from the hot fuel gases before it leaves the chimney.

   Advantages of Economizer:

  • The long life of the boiler.
  • To increase in the evaporative capacity of the boiler.

2. Feed pump

  • It use to deliver water to the boiler.

      There are mainly two types of feed pump:

   i. Reciprocating feed pump

  • This is positive displacement type pumps. The most popular types of reciprocating feed pump used in a boiler is a duplex feed pump.
  • It consists of a steam engine and a water pump side by side.

  ii. Rotary feed pump

  • It is a high speed centrifugal pump that is used to deliver a large quantity of water into the boiler.
  • It consists of impeller and casing.

3. Super heater

  • It is a heat exchanger in which products of the heat of combustion is utilized to dry the wet steam and to make super heated by increasing it’s temperature.
  • During this process, pressure remains constant and it’s volume and temperature increase. It consists of a set of small diameter U – tube in which steam flows and takes up the heat from hot flue gases.

Advantages:

  • To increase overall efficiency.
  • There is a saving in fuel consumption.

4. Air preheater

  • It is a device which designed to heat air before another process with the primary objective of increasing the thermal efficiency of the process.

For Better Understanding Watch This Video Clip

 

https://mechanicalnotes.com/boiler-definition-principle-working-properties-classification-component/

 https://mechanicalnotes.com/centrifugal-pump-definition-types-parts-working-and-diagram/

 

 

Boiler

  • A Boiler or steam generator basically is a compartment into which water can be bolstered and steam can be taken out at wanted pressure, temperature and stream.
  • For that the evaporator ought to have an office to consume a fuel and discharge heat. Along these lines the capacity of a heater can be expressed as :

    i. To change over compound vitality of the fuel into heat vitality.

   ii. To move this warmth vitality to water for dissipation too to steam for super warming.

Schematic diagram of Boiler

schematic diagram of boiler

Definition of Boiler

  • It is characterize as a shut vessel wherein steam is created from water by ignition of fuel. 

or

  • A boiler is a closed pressure vessel strongly constructed of steel or iron where water is converted into steam by the application of heat.

Efficiency 

  • The efficiency of a boiler may be defined as the ratio of amount of steam generated per hour to the amount of heat supplied by the fuel per hour.

                            

  Efficiency ( η ) = ( Heat Output / Heat Input ) × 1oo

 

https://mechanicalnotes.com/cochran-boiler-definition-main-parts-working-features-advantages/

Principle & Working of Boiler

Principle 

  • In an evaporator, the warmth vitality of the pipe gases move to the water through convection. The fuel is consume into the heater which produces vent gases.
  • These pipe gases ignore the water containing in shell or cylinder as indicated by the sort of heater. The warmth of the vent gases move to the water and convert it into steam.

working principle of boiler

Working 

  • A boiler is simply  heat exchange in which, water is work as cold fluid and flue gases works as hot fluid. The heat flow is transfer from hot fluid to cold fluid through convection which increases the energy of water.
  • A container half filled with water. The fuel is consume and the vent gases stream over the holder. These gases heat the water and covert it into steam.
  • This steam taken out from a cylinder arranged upper side of the holder. The equivalent measure of water is feed into the holder by the feed valve which keep up the kettle pressure unaltered.
  • If the steam escaping rate is high compare to water feeding rate,the pressure of boiler decreases. What’s more, if the water nourishing rate is high contrast with steam getting away from rate the weight of the heater increments. Thus pressure is control with the help of  fuel supply and water supply of container.

Function & Properties of a good boilers

  • To change over substance vitality of the fuel into heat vitality.
  • To move this warmth vitality to water for dissipation too to steam for super warming.
  • It can be started or stopped quickly.
  • It should have a constant and through circulation of water.
  • All pieces of heater ought to be open for cleaning and review.
  • It should be trouble  free & require less attention and less maintenance.
  • It ought to have high pace of warmth move and better burning effectiveness.
  • They having free from manufacturing defects.
  • It should be able to accommodate the load variation.
  • They having maximum steam generation rate within minimum fuel consumption.
  • Initial cost, running cost & maintenance cost are not high.

Classification of Boiler

      The boilers may be classify mainly on the basis of the following parameters:

1. Axis of the shell

   a. Vertical 

   b. Horizontal

   c. Inclined

2. Use of boilers

 a. Stationary 

 b. Portable

3. Tube contents

 a. Fire tube

 b. Water tube

4. Furnace position

a. Externally fired

b. Internally fired

5. Method of water circulation

a. Natural circulation

b. Forced circulation

1. Axis of the shell

a. Vertical 

  • If the axis of the boiler is vertical then it  called as vertical boiler.
  • It’s occupy less floor space.

b. Horizontal

  • If the axis is horizontal than it called as horizontal boiler.
  • The pieces of a flat evaporator can be reviewed and fixed effectively yet it consumes more space.

c. Inclined

  • If the axis is inclined than it called as inclined boiler.

2. Use of boilers

a. Stationary

  • Stationary boilers are utilized for power plant steam for focal station utility force plants, for plant process steam and so on.

 b. Portable

  • Portable boilers are portable and are of small size.
  • For example:- Locomotive and Marine boilers.

3. Tube contents

 a. Fire tube

  • In fire tube boilers, the hot gases are inside the tubes and the water surrounds the tubes.
  • For example:- Cochran, Lancashire and Locomotive boilers etc.

Fire tube boilers are:

  • Relatively inexpensive.
  • Easy to replace tubes.
  • Easy to clean.
  • Compact in size.
  • Available in size from 600,000 btu/hr to 50,000,000 btu/hr.
  • Appropriate for space warming and modern procedure applications.

     Disadvantages

  • Limitation for high capacity steam generation.
  • Not appropriate for high weight applications 250 psig or more..

b. Water tube

  • In this case of water tube boiler, the water is inside the tube and hot gases surround them.
  • For example:- Babcock and Wilcox, Stirling, Yarrow etc.

   Water tube boilers:

  • Faster recover than their fire-tube cousin.
  • They have ability to reach very high temperatures.
  • They are able to handle higher pressures upto 5,000 psig.
  • It’s available in sizes far greater than a fire tube design, up to several million pounds per hour of steam.

    Disadvantages

  • High initial capital cost.
  • No commonality between tubes.
  • Phsical size may be an issue.
  • Cleaning is more difficult due to the design.

4. Furnace position

a. Externally fired

  • The boiler is known as externally fired if the heat addition is done externally i.e. furnace is outside the unit.
  • For example:- Babcock & Wilcox etc.

b. Internally fired

  • In case of internally fired boiler, heat addition is done internally i.e. furnace is within the unit.
  • For example:- Cochran and Lancashire.

5. Method of water circulation

a. Natural circulation

  • In natural circulation boilers, the circulation of water/steam is caused by the density difference which is due to the temperature variation.
  • For example:- Lancashire

b. Forced circulation

  • In constrained dissemination sort of boilers, the flow of water is finished by constrained siphon.
  • For example:- Velox, Lamont etc.

Basic components of Boiler

  • Furnace
  • Economiser
  • Air -Preheater
  • Super heater
  • Re – heater
  • De -Super heater
  • Condenser
  • Cooling tower
  • Fan or draught system
  • Ash handling system

Applications of Boiler

They having a very wide application in different industries such as

  • Power Sector
  • Thermal Power Plants
  • Sugar Plants
  • FM CG
  • Food Processing Industries etc

 Thanks for reading. If the articles help you then please spread your love and don’t forget to share it on social network’s.