Knurling adds gripping texture to round shafts. Common on knobs, handles, and shaft adapters.
Knurling Methods
- Form (compression) knurling — Most common. Wheel(s) press into rotating workpiece. No chips.
- Cut knurling — Special tool cuts pattern. Better for hard materials.
Pattern Types
- Straight — Parallel lines. Best rotational grip, no axial.
- Diagonal — Single helical. Good general-purpose.
- Diamond (cross) — Two helical crossing. Best grip in all directions.
- Convex — Bumps for tactile feel
Knurling Wheels
| TPI | Pattern | Use |
|---|---|---|
| 14 TPI | Coarse | Heavy industrial grip |
| 21 TPI | Medium | Standard tool handles |
| 33 TPI | Fine | Small precision parts |
Tool Holder Types
- Push-type (single wheel) — Simple, requires high force
- Bump-type (two wheels) — Balanced force
- Scissors-type (multi-wheel) — Self-centering. Best for production.
Parameters
- RPM: 30-100 (much slower than turning)
- Feed: 0.10-0.25 mm/rev
- Depth: 0.3-0.8mm depending on TPI
- Coolant: flood with EP additive
Workpiece Diameter Calculation
For clean knurl pattern, workpiece diameter must produce whole number of teeth:
Optimal OD = (n × 25.4) / (π × TPI) where n is whole number.
For 21 TPI: clean diameters are 20.0mm, 22.4mm, 25.0mm, etc.
Browse knurling tools in our specialty catalog.
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