
15
CUTTING SPEEDS
Factors which determine the best speed to use in any drill press operation are:
1. Kind of material being worked.
2. Size of hole.
3. Type of drill.
4. Quality of cut desired.
Generally, the smaller the drill, the greater the required RPM. In soft material, the
speed should be higher than for hard metals.
As a guide, the drill speed for a given drill bit size, is according to the table below.
Wood
2740
1410 -
2270
970 -1280 480 - 580
250 - 400 180
Speed Range
(RPM)
in3/81/2----
mm 9.5 12.5 - - - -
Zinc in 1/4 3/8 1/2 - - -
Diecast mm 6.4 9.5 12.5 - - -
Alum & in 7/32 11/32 15/32 - - -
Brass mm 5.6 8.75 12 - - -
in 3/16 5/16 7/16 - - -
mm 4.8 7.9 11 - - -
Cast Iron in 1/8 1/4 11/32 1/2 - -
& Bronze mm 3.2 6.4 8.75 12.5 - -
Mild Steel in 3/32 5/32 1/4 3/8 1/2 -
& Malleable mm 2.4 4 6.4 9.5 12.5 -
Cast Steel in 1/16 1/8 3/16 5/16 7/16 1/2
& Med Carbon mm 1.6 3.2 4.8 7.9 11 12.5
Stainless in 3/64 1/16 1/8 1/4 3/8 1/2
and Tool Steel mm 1.2 1.6 3.2 6.4 9.5 12.5
Plastic
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