Radial Chip Thinning Calculator

Compensate feed and speed for HEM, HSM, trochoidal, and peel milling — run aggressive MRR with shallow radial cuts.

What is chip thinning? When radial engagement is less than half the tool diameter, actual chip thickness is smaller than your programmed feed per tooth. Compensating lets you run full axial depth with a shallow radial bite — the whole basis of modern HEM / HSM toolpaths. SFM bump is Guhring HPC-style.
inches
teeth
inches
inches
SFM
in/tooth
Invalid setup: Radial DoC must be less than the tool diameter — you can't engage more than the tool itself.
+117%
feed rate increase at 10.0% radial engagement
1.67×
Chip Thinning Factor
1.30×
SFM Multiplier

Baseline (No Compensation)

SFM400
RPM3056
IPT0.0030 in
Feed36.7 IPM
MRR1.83 in³/min

Compensated (HEM)

SFM520
RPM3973
IPT0.0050 in
Feed79.5 IPM
MRR3.97 in³/min

Multiplier reference (Guhring HPC-style)

EngagementChip Thinning FactorSFM MultiplierApprox. Feed Increase
50%1.00×1.00×+0%
25%1.15×1.15×+32%
15%1.35×1.20×+62%
10%1.67×1.30×+117%
5%2.29×1.50×+244%
3%2.97×1.70×+405%

Formulas

CTF = D / (2 × √(RDoC × (D − RDoC))) = 0.5 / (2 × √(0.05 × 0.45)) = 1.667 Compensated IPT = 0.003 × 1.667 = 0.00500 Compensated SFM = 400 × 1.300 = 520 Compensated RPM = (520 × 3.82) / 0.5 = 3973 Compensated Feed = 0.00500 × 3973 × 4 = 79.5 IPM