Calculation policy
MachiningCalc uses standard geometric relationships for surface speed, RPM and feed. The first release does not claim to choose an optimal SFM or chip load for every material and cutter combination. Those inputs should come from the tooling manufacturer or a validated shop process.
Core inch formulas
| Output | Formula |
|---|---|
| SFM | π × diameter × RPM ÷ 12 |
| RPM | SFM × 12 ÷ (π × diameter) |
| Milling feed | chip load × RPM × effective teeth |
| Milling MRR | axial DOC × radial WOC × IPM |
| Turning feed | RPM × feed per revolution |
Surface finish model
The turning surface-finish calculator uses the ideal round-nose geometric approximation Ra ≈ f²/(32r). It is explicitly labeled theoretical because measured finish also depends on vibration, wear, built-up edge, material behavior and inspection settings.
Technical references
- Sandvik Coromant — milling formulas, inch
- Sandvik Coromant — turning formulas, inch
- Harvey Performance — speeds, feeds and chip load formulas
Editorial principle
Every calculator should solve one primary task, disclose its formula, state its assumptions and link to the next logical machining calculation. Material-specific presets will only be added when the underlying data can be sourced and scoped by tool class and operation.