Face mill speed and feed calculator converts cutter diameter, target surface speed, insert count, and feed per insert into spindle RPM and table feed rate.
Get RPM and table feed for a face mill from cutter diameter, target SFM, insert count, and feed per insert.
RPM = (SFM x 3.82) / D. Feed = RPM x Feed per Insert x Number of Inserts.
How it works
Face milling uses the same speed and feed math as end milling, just with insert count standing in for flute count. Cutter diameter for SFM purposes is the actual cutting diameter, not the body diameter.
FAQ
Do all inserts need to engage every revolution? No, but the feed-per-insert number assumes full engagement; reduce it if only some inserts are cutting on a given pass.
Related Guides
CNC Calculators · End Mill Speed and Feed Calculator · SFM Calculator
How it works
Face mills are rated by number of inserts rather than flutes, and feed per insert, not per flute, is the value manufacturers publish, so feed rate is RPM times feed per insert times insert count, the same structure as chip-load-based feed calculations for end mills. Larger-diameter face mills need a lower RPM to hold the same SFM, similar to any other milling cutter.
FAQ
Why does my face mill leave a poor finish even at the recommended speed and feed? Common causes unrelated to speed and feed include an insufficient lead angle causing rubbing rather than cutting, a worn or chipped insert, spindle runout, or the cutter’s centerline not passing exactly over the part centerline on some finishing operations.
Related Guides
CNC Calculators · End Mill Speed and Feed Calculator · Material Removal Rate Calculator