Chapter 10
Spindle speeds and travel
Determining Speeds for Milling
Speeds
Milling cutting rates vary according to the machinability of the material being
cut; whether cutting fluid is used and, if so, what kind; the type, size, and
material of the cutter and the coarseness of its teeth; and the amount of
metal being removed. Cutting speed for milling is the distance the cutting
edge of a tooth travels in one minute. If cutting speed is too high, the cutter
overheats and becomes dull. If it's too low, production is inefficient and
rough.
There is no exact right cutting speed for milling a particular material.
Machinist usually start with an average speed, then increase or decrease it
as needed. For light cuts, use the upper end. Use the lower end for heavy
cuts and when you don't use cutting fluid.
Determining rpm.
To set the spindle speed, you have to know the cutter
rpm (revolutions per minute).
For inch measurements, use this formula:
rpm = 12 x CS (fpm) / D” x π
where:
CS - cutting speed
fpm -feet per minute
D” - diameter of the cutter in inches
π = 3.14 You can use an rpm chart for selected diameters of cutting tools at
different cutting speeds.
For metric measurement, use this formula:
rpm = CS (rpm) x 1000 / D (mm) x π
where:
CS - cutting speed
mpm - meters per minute
D (mm) - diameter of the cutter in millimeters
π = 3.14. You can use an rpm chart for selected diameters of cutting tools at
different cutting speeds.
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Summary of Contents for MI-329M
Page 1: ...Smithy MI 329M Operator s Manual 1 ...
Page 30: ...Chapter 13 Diagrams and Parts Listings 30 ...
Page 33: ...33 ...
Page 37: ...37 ...
