Table 7-2.--Surface Cutting Speeds
cutter, or the work at the suggested speed, make an
immediate readjustment.
Use table 7-3 to determine the cutter rpm for
cutters varying in diameter from 1/4 inch to 5 inches.
For example: You are cutting with a 7/16-inch cutter.
If a surface speed of 160 fpm is required, the cutter
rpm will be 1,398.
If the cutter diameter you are using is not shown
in table 7-3, determine the proper rpm of the cutter by
using the formula:
Cutting speeed 12
(a) rpm =
3.1416 Diameter
fpm
or rpm =
0.2618 D
where
rpm = revolutions per minute of the cutter
Use the approximate values in table 7-2 as a guide
fpm = required surface speed in feet per minute
when you select the proper cutting speed for
D = diameter of the cutter in inches
high-speed steel cutters. Refer to the manufacturer's
recommendations if you are using carbide tooling. If
0.2618 = constant =
you find you cannot suitably operate the machine, the
Table 7-3.--Cutter Speeds in Revolutions Per Minute
7-50