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By straight knurling gripping surfaces are produced, e.g on screws, round nuts and control knobs. Attention is to be paid to the following:
- The workpiece is clamped in a chuck. For longer parts the live centre is used as counter-support.- Hard chuck jaws are mainly used.
- The knurling wheel is fixed in the holder by an unhardened steel pin (see Fig. 4).
- The knurling tool holder is to be clamped approx. 1 mm below centre and at right angle to the work-piece axis.
- Mislocation (oblique position) of the tool will result in failures and should be avoided.
- By operating the cross-slide screw, the tool is pressed against the workpiece.
- Firm and safe clamping of the workpiece and tool are important because of the high pressing force.
- If possible, the knurling should be produced in one feed setting.
- Sufficient cooling and lubrication are to be ensured.
- The edges of the workpiece are to be chamfered after knurling since the material is also pressed to the end faces. The amount of chamfer should be approximately equal to the pitch (chamfer = t).
- By visual inspection the grooves are checked for cleanliness.
Figure 15 Working position of tool
1 straight knurling holder
2 workpiece
Figure 16 Misplacement of tool
Figure 17 Chamfering of workpiece
1 chamfer
2 pitch
3 workpiece
What is the purpose of straight
knurlings?
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