Capstan and Turret Lathe-Introduction, Working, Advantages, Difference, Holding Device

Capstan and Turret Lathe:

Introduction:

  • A  Capstan and Turret lathe is fundamentally production lathe. It is used to manufacture any number of identical pieces in the minimum time.
  • It was modified of engine lathes.
  • They were first developed in United State of America by PRATT and WHITNEY IN  1860.
  • Capstan and turret lathes are Semi-automatic lathes that help in making the Auxiliary motion quick and accurate.
  • The Tail stock is replaced by an index able multi station tool head.
  •  Turret head has a Hexagonal block having six faces with a bore for mounting six or more than six tools at a time. The threaded hole on these faces are used to hold the tools.

Brief working:

  • The work piece is held in collect or chucks that is actuated hydraulically or pneumatically. On the turret head, all the needed tools are held in the respective holes.
  • The tool is moved with the help of turret head, according to the sequence of operation.
  • Drilling, boring, turning, reaming, threading tools are mounted on the turret head.
  • Forming, Chamfering, Knurling tools are mounted on the front end of the turret.
  • The Parting tool is mounted in an inverted position on the rear end of the turret.
  • The turret head is moved back to its initial position after completing each operation where indexes the tools automatically.

Advantages:

  • The production rate is high.
  • Different ranges of speeds are obtained.
  • A number of tools can be accommodated.
  • Less skill operators are required hence lowers the labor cost.
  • higher rigidity so can withstand heavy loads.

Difference Between Capstan and Turret lathe:

 

S. No. Capstan lathe Turret lathe
1. The turret head is mounted on the ram and the ram is mounted on the saddle. The turret head is directly mounted on the saddle and the saddle slides over the bed ways.
2 The saddle is fixed during machining. The saddle is moved along with the turret head during machining.
3 The turret head can’t be moved crosswise. The turret head can be moved crosswise.
4 The lengthwise movement of turret is less. The lengthwise movement of turret is more.
5 Maximum bar size is up to 60 mm  Maximum bar size is up to 200 mm 
6 Collect is used to hold the work piece. Jaw chuck is used to hold the work piece.
7 Rate of tool feeding relatively faster Rate of tool feeding relatively slower
8 It is a light weight machine It is a heavier machine
9 It has a simple tool head. It has hexagonal tool head.
10 Automatic indexing. Manual indexing.

Capstan and Turret Lathe Tools:

  1. Turning tool
  2. Facing tool
  3. Parting tool
  4. Forming tool
  5. Chamfering tool
  6. Drilling
  7. Boring tool
  8. Counter bore
  9. Reamer
  10. External thread cutting tool
  11. Internal thread cutting tool
  12. Workstop

1. Turning tool:

  • Turning tool is mounted on the cross-slide or knee holder.
  • Hollow mill  is a special turning tool used in capstan and turret lathe.

2.  Facing tool:

  • Facing tool may be mounted on the cross-slide or on the knee tool holder.

3. Parting tool:

 

  • The tool is mounted on the rear tool post.
  • All round clearance is given on tool to clear the work while cutting.

4. Forming tool:

  • The forming tools may be straight or circular type.

5. Drill:

  • The twist drill is mounted on the turret face holders are the standard tools used for drilling holes.

6. Boring tool:

  • The boring tools mounted on boring bars are used for enlarging a hole in a capstan or turret lathe.

7. Counter bore:

  • The counter bores are used for enlarging the drilled hole from one end.

8. Reamer:

  • The reamer are used for sizing and finishing a hole.
  • Reamers may have two or more straight or helical flutes in the body.

9. External thread cutting tool:

 

  • External thread are cut on a job in a capstan or turret lathe by using any one of the following tools:

a. Solid button dies:

b. Chasers:

  1.  Radial chaser

           ii.Tangential chaser

                 iii.Circular chaser

 

c. Single point tools:

10. Internal thread cutting tool:

  • The internal thread may be cut in a capstan or turret lathe by using any one of the following tool:

a. Solid tap

b. Collapsible tap

c. Single cutting tool or chaser

11. Chamfering tool:

  • The chamfering tool is mounted on the four station turret on cross-slide.
  • The extreme longitudinal position of the saddle is adjusted by a stop.

12. Workstop:

  • It is mounted on the turret face for maintaining correct length of bar for machining .
  • After it has been pushed through the collet chuck.

Work Holding Devices & Tool Holding Devices:

S.NO. Work Holding Devices Di gram S.NO. Tool Holding Devices Di gram
1. jaw Chucks 1. Straight cutter holder
a. Self centering chuck 2. Multiple cutter holder
b. Independent chuck 3. Offset cutter holder
c. Combination chuck 4. Combination tool holder
d Air operated chuck 5. Knee tool holder
2. Col let chucks 6. Slide tool holder
a. Push out type 7. Knurling tool holder
b. Draw in type 8. Boring bar holder
c. Dead length type 9. Recessing tool holder

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