The pair of numbers that decide how a cut behaves: spindle speed, derived from surface speed for the material and tool, and feed rate, derived from chip load per tooth times number of flutes times rpm. Getting them right balances tool life, finish, chip control and cycle time. Starting values come from tooling catalogs and handbooks and are then tuned by sound, chip color and finish.
Feeds and speeds out of the catalog are a starting point, listen to it and watch the chips before you push it.
Also heard as
- speeds and feeds
Related terms
SFM
Surface feet per minute: how fast the cutting edge moves across the work, the basis for spindle speed.
Chip load
The thickness of material each cutting edge takes per revolution, also called feed per tooth.
Chatter
Self-sustaining vibration between tool and work that screams, leaves a wavy pattern and kills tools.
Blue chips
Steel chips that come off straw to dark blue from heat, read as a sign of how hard a cut is running.