Precision matthews PM-1127VFI-LB, Safety & Training Manual

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Feed, Speed, and Depth of Cut
Cutting speed is defined as the speed at which the work moves
with respect to the tool (usually measured in feet per minute).
Feed rate is defined as the distance the tool travels during one
revolution of the part.
Cutting speed and feed determines the surface finish, power
requirements, and material removal rate.
The primary factor in choosing feed and speed is the material to
be cut. However, one should also consider material of the tool,
rigidity of the workpiece, size and condition of the lathe, and
depth of cut.
Softer materials such as plastics, aluminum and brass can be
cut at higher speeds than harder materials such as steel.
For most Aluminum alloys, on a roughing cut (.010 to .020
inches depth of cut) run at 600 fpm. On a finishing cut (.002 to
.010 depth of cut) run at 1000 fpm.
To calculate the proper spindle speed, divide the desired cutting
speed by the circumference of the work. Experiment with feed
rates to achieve the desired finish.
In considering depth of cut, it's important to remember that for
each thousandth depth of cut, the work diameter is reduced
by
two thousandths.
When in doubt always start at a slower speed and feed rate.