Machining Speed and Feed
Spindle speed (RPM) from surface speed (SFM) and cutter or work diameter.
Example
You enter
- Surface speed (SFM) 100
- Diameter (in: cutter for mill/drill, work for turning) 0.5
- Flutes / teeth (optional, for feed) 2
- Chip load per tooth (in, optional) 0.002
You get
- Spindle speed 764 RPM
- Feed rate 3.056
Details, formula, and sources
Spindle speed (RPM) from surface speed (SFM) and cutter or work diameter, plus feed rate (IPM) from the number of flutes and chip load per tooth (first-principles cutting geometry; Machinery's Handbook speeds-and-feeds method).
RPM = 12 * SFM / (pi * dia(in)); feed IPM = RPM * flutes * chip_load(in/tooth); 12/pi = 3.8197.
First-principles cutting geometry; the speeds-and-feeds method as in Machinery's Handbook (Industrial Press), by name.
Pure geometry, public; the surface speed (SFM) and chip load per tooth are user-supplied from the tool / material chart.
Estimate. AHJ and licensed professional govern.
Field names used by the API: surface_speed_sfm, diameter_in, num_flutes, chip_load_in, rpm, feed_ipm
- Chart inputs recommended SFM and chip load per tooth are user-supplied from the tool/material charttool manufacturer data