08-04-2014, 06:39 AM
Surface feet per minute (or meters per minute) are always a function of the diameter of a cutter and the RPM. Change one, the other has to change with it.
You want to avoid really light feed rates with coated carbide because you'd be just "rubbing" and wear it out prematurely. Always give it some work to do. In the case of a machine with a feed unit limited to 7.5" per minute, you could figure this out backwards easily. Divide 7.5" by (.005 feed per tooth x 4 teeth) = 375 rpm. A 2" cutter at 375 rpm is only running 196 sfm. That's really on the low side for carbide inserts, but they should survive.
You want to avoid really light feed rates with coated carbide because you'd be just "rubbing" and wear it out prematurely. Always give it some work to do. In the case of a machine with a feed unit limited to 7.5" per minute, you could figure this out backwards easily. Divide 7.5" by (.005 feed per tooth x 4 teeth) = 375 rpm. A 2" cutter at 375 rpm is only running 196 sfm. That's really on the low side for carbide inserts, but they should survive.