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Cutting Parameters

Surface Speed Calculator for CNC Machining

Convert spindle RPM and tool or workpiece diameter into surface speed in m/min and SFM. Use it to compare cutting data across metric and imperial tooling charts.

Input Parameters

Results

SFM (m/min)
SFM (ft/min)
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Surface Speed formula and how to use it

Surface speed should be selected by material, tool substrate, coating, operation type, and coolant condition.

Frequently asked questions

What is surface speed?

Surface speed is the speed of the cutting edge relative to the workpiece surface. It is commonly expressed as m/min or SFM.

Is SFM the same as RPM?

No. RPM is spindle speed. SFM changes with diameter, so the same RPM produces different surface speeds on different tool or workpiece diameters.

When should I lower surface speed?

Lower it for hard materials, poor coolant, long reach tools, unstable setups, interrupted cuts, or rapid edge wear.

How to use this Surface Speed calculator

Use this calculator to translate between spindle RPM and cutting speed so metric and imperial tooling charts can be compared correctly.

Common mistakes to avoid

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