KEVOS® MAKEOS · Manufacturing
Chip Thickness and Specific Cutting Force
What mean chip thickness does this cut produce, and what specific cutting force results?
Mean chip thickness for milling (from feed per tooth, radial engagement and lead angle) or turning, and the specific cutting force kc from the material’s kc1.1 and exponent mc, for use in power calculations.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Operation | choice | Milling or turning. |
| Feed per tooth (milling) or per rev (turning) | mm | Feed per tooth (milling) or per revolution (turning). |
| Radial engagement (milling) | mm | Width of cut across the cutter (milling). |
| Cutter diameter (milling) | mm | Cutter diameter (milling). |
| Lead (entering) angle κr | ° | Lead or entering angle of the cutting edge (90° for a square shoulder cutter). |
| kc1.1 (specific force at 1 mm chip) | N/mm² | Specific cutting force at 1 mm chip thickness and 0° rake for the material, from tooling data (steel about 1500–2100, aluminium 500–800 N/mm²). |
| Exponent mc | Chip thickness exponent from the same data (about 0.2–0.3). | |
| Effective rake angle | ° | Effective rake angle of the insert (positive rake lowers the force by about 1% per degree). |
Method and formulas
- Milling: hm = (360 × fz × sin κr × ae) ÷ (π D φ), with engagement angle φ = arccos(1 − 2ae/D) in degrees (for ae ≤ D/2).
- Turning: h = f sin κr.
- kc = kc1.1 × h^(−mc) × (1 − rake/100).
- Example: 0.15 mm/tooth with 20 mm of a 50 mm cutter gives hm = 0.087627 mm and kc ≈ 3,124.6 N/mm².
Limitations
- Engagement angle formula assumes the cutter centre outside the material (ae up to D); slotting uses full engagement.
- Material data vary; use the tool maker’s kc1.1 and mc for the actual grade.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Get the right kc for the milling and turning power tools
- See how light radial engagement thins the chip
- Compare feeds for efficient cutting
Who it is for
- Machinists
- CNC programmers
- Manufacturing engineers
What you get
- Mean chip thickness
- Engagement angle (milling)
- Specific cutting force kc
Interpreting the result
- Thin chips raise kc; keeping hm near the tool maker’s recommendation improves tool life and efficiency.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1084–1101. Topic reference; no source tables or recommended settings are reproduced.
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