CNC MILLING SPEEDS AND FEEDS
The spindle speed you should use for a cutter and the feed rate (the speed at which the cutter should move through the work) depends on a number of factors, not least of which is the rigidity of the milling machine. There is a wide variation in rigidity between machines, and the physical size, fit of the slides and condition of the leadscrews will all have an effect. In practice, theoretical speeds that would be ideal for a robust mill in a factory must be reduced as the size and rigidity of the milling machine are reduced.
Ideal spindle speeds, in revs per minute, for small cutters are likely to be unattainable on small machines unless fitted with a high-speed spindle, so there is a compromise here, too. Just get as close as you can to the ideal and accept the compromise in what a particular mill can achieve. To calculate the spindle speed for a highspeed steel cutter, we need to know the cutting speed appropriate for the material being machined and the diameter of the cutter. Typical cutting speeds are shown in Table 4-4.
