Cutting Speeds

Different materials should be worked at different speeds, and the speed should depend on the type of cutter being used (a carbide cutter should be run faster). The following discussion assumes a HSS (high speed steel) cutter.

Note that these speeds are generally the fastest speeds which should be used and ought to be treated as upper limits. In industry, maximizing production and throughput are usually top priority and the tendency is to push machines as hard as possible. Lower speeds will give longer tool life.

Some materials though may not give best results when machined at too slow of a speed. Brass is notable in this way.

Cutting speed is given as "sfm" (surface feet per minute) 

Alloy (tough) steels - 50-60 sfm
Cast iron - 60-80 sfm
Cold Rolled Steel (CRS) - 80 sfm
Mild Steel - 120 sfm
Bronze - 150 sfm
Aluminum - 300 sfm
Brass - 600+ (as fast as you can spin)
The calculation is simple: sfm = pi * d * rpm / 12

Alan Koski (10-13-2010) provided a table with information specific to his mill.

For aluminum, here are the speeds which could be used with some common cutters:

CutterRPM
1/1618335
1/89167
1/44584
3/83056
1/22292

And here are the speeds for mild steel:

CutterRPM
1/167334
1/83667
1/41833
3/81222
1/2917

Have any comments? Questions? Drop me a line!

Tom's home page / tom@mmto.org