Calculation method
Calculation
RPM = SFM × 12 ÷ (π × Diameter)IPM = RPM × Effective Teeth × Chip LoadMRR = Axial DOC × Radial WOC × IPMUse values in the units shown by the calculator. Inputs must be positive and physically meaningful.
How to use the cutting speeds and feeds calculator
Enter a validated cutting speed, the actual cutter diameter, effective teeth and chip load per tooth. RPM and IPM update immediately. Depth and width of cut are optional inputs used only for the material-removal estimate.
Speed in milling
Milling spindle speed is set by surface speed and cutter diameter. A smaller cutter needs more RPM for the same SFM. Feed rate then adds the tooth count and chip load, so two cutters running the same RPM can require very different IPM.
| Input | What it represents | Where to get it |
|---|---|---|
| SFM | Target cutting surface speed | Tool manufacturer cutting data |
| Diameter | Effective cutting diameter | Tool geometry / setup |
| IPT | Chip load per effective tooth | Tool manufacturer cutting data |
| Flutes | Effective cutting teeth | Tool geometry |
How to interpret RPM, IPM and MRR
RPM is the spindle setting implied by SFM and diameter. IPM is the programmed linear feed when chip load and tooth count are known. MRR is a geometric comparison of volume removed per minute; it does not predict spindle load or tool life.
Factors that affect the result in the real cut
Radial engagement can cause chip thinning; tool runout changes chip load tooth-to-tooth; long stickout lowers rigidity; machine acceleration may prevent small features from reaching programmed feed. Treat the result as a clean baseline, then apply toolmaker corrections and shop limits.
Methodology, standards and validation
MachiningCalc separates deterministic math from cutting-data recommendations. The calculator performs the geometry and unit relationships; the correct starting cutting data still depends on the tool, work material, coating, machine and setup.