4140 alloy steel turns predictably with good chip formation. In the annealed state, it is straightforward to machine. Pre-hardened material requires more attention to tooling and parameters.
| Parameter | Value |
|---|---|
| Achievable Tolerances | ±0.01 mm (±0.0004") |
| Surface Finish | Ra 0.4-1.6 μm |
| Cutting Speed | 150-250 m/min (annealed) |
| Feed Rate | 0.10-0.30 mm/rev |
| Tooling Recommendations | Carbide inserts grade P20-P30 with TiCN or TiAlN coating. Use heavy-duty insert grades for pre-hardened. |
Use inserts rated for interrupted cuts if pre-hardened
Flood coolant for heat dissipation
Chip-breaking inserts recommended
Reduce speed 30-40% for pre-hardened stock
Shafts and axles
Coupling hubs
Sprocket hubs
Piston rods
Toolholder bodies
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