Calculate cutting surface speed from tool diameter and spindle RPM, or calculate the required spindle RPM from a target surface speed.
Enter diameter and spindle speed to calculate.
What is CNC surface speed? Surface speed is the linear speed of the cutting edge as it travels around the rotating tool or workpiece.
What is the difference between RPM and surface speed? RPM describes how fast the spindle rotates. Surface speed describes how fast the cutting edge travels relative to the workpiece. Surface speed depends on both RPM and diameter.
How does diameter affect surface speed? At a fixed RPM, increasing diameter increases surface speed proportionally.
How do I calculate RPM from cutting speed? For metric units, multiply target surface speed in m/min by 1000 and divide by π times diameter in mm.
What is SFM? SFM means surface feet per minute and is the imperial unit commonly used for cutting surface speed.
Can this be used for milling? Yes. Enter the milling cutter diameter and spindle RPM to calculate the cutter's surface speed.
Can this be used for turning? Yes. Enter the workpiece diameter and spindle RPM. For CNC turning with constant surface speed, RPM may change continuously as the diameter changes.
Does tool engagement affect surface speed? The basic geometric surface-speed calculation does not account for engagement. However, radial and axial engagement can affect the appropriate recommended cutting conditions.
Can surface speed be too high? Yes. Excessive surface speed can increase cutting temperature, tool wear and the risk of tool failure depending on the material and cutting tool.
Should I use the calculated RPM exactly? Use the calculated value as the mathematical target, then consider the machine's maximum RPM, available spindle settings, tooling recommendations and actual cutting conditions.