Bar peeling - how the process works

During bar peeling, bars and tubes made from various carbon steels, spring steels, stainless steels, nickel-based alloys, titanium and aluminium are processed with the desired surface quality, dimensional accuracy and geometrical accuracy. During this peeling process, a number of rough forged and bent or rolled workpieces in the diameter range from 10 to 650 mm are machined to produce a bright, smooth surface and remove cracks caused by the forging and rolling process. 

This heavy machining process is seen as extremely productive and efficient, but at the same time especially challenging for tools and machines. The significantly reduced throughput times compared with the conventional turning process and first-class result for bright steel products with regard to surface quality and dimensional accuracy reduce costs and rework efforts for these semi-finished products.

Schematic representation of a peeling machine

1. Feeding mechanism

2. Entry guide rollers

3. Peeling insert

4. Tool slide/cartridge

5. Exit guide rollers

5. Exit guide rollers

6. Tool adjustment motor

7. Measuring device

8. Withdrawal jaw carriage

9. Entry guide

10. Turning centre

11. Feeding mechanism motor

12. Peeling head

13. Conical ring

14. Hollow shaft

15. Main gearbox

16. Main motor

17. Withdrawal jaw carriage motor

18. Exit guide

Internal peeling

During internal bar peeling, seamless steel tubes, cold-welded or cold-drawn precision steel tubes - which are used for manufacturing cylindrical tubes, for example - are finish machined on the internal diameter. In most cases, a combination of peeling and smooth rolling tools is used.

In the front area of the internal peeling head, the internal peeling inserts are positioned in cartridges and clamped. Only two indexable inserts are usually involved, which are positioned at an offset of 180° to the diameter. To increase the material removal rate, tandem systems are also used, on which two internal peeling inserts are positioned one behind the other in a cartridge in the axial direction. Using the downstream smooth rolling tool, the peeling surface is optimised further with roller pressure and rotation in the same operation, the material is compressed, roughness and unevenness are depressed and the inner tube surface is therefore more level, smoother and more wear resistant.

  1. Workpiece (tube)
  2. Peeling head guide pad
  3. Smooth rollers
  4. Internal peeling head
  5. Cartridge
  6. Internal peeling insert
  7. Smooth roller head
  8. Bar guide pad