Exact circumference arithmetic
Cutting Surface Speed ↔ Spindle Speed
Convert between peripheral cutting surface speed and spindle rotational speed using the actual cutting diameter for the operation. Metric and inch formulas are evaluated directly in their stated units.
Kinematic conversion
These are circumference-times-revolutions unit identities, not ISO acceptance formulas. Sandvik Coromant metric milling formulas define Dcap as the cutting diameter at cutting depth ap and give both metric equations. The official inch milling formula sheet gives the corresponding factor 12.
Cutting surface speed is a kinematic quantity, not an intrinsic material property. A recommended value is an operating selection. Kennametal’s official guidance identifies work-material hardness/heat treatment/alloy, tool material/shape/condition, coolant and fixture stability as relevant inputs. The former generic HSS/carbide material table and presets did not identify these conditions and have been removed.
No machine-command guarantee: compare calculated n with tool-holder/tool maximum speed, spindle range, workholding/chuck limits, workpiece integrity, balance, machine torque/power and OEM restrictions. Never exceed the lowest applicable rated speed.
