How do you estimate material removal rate on a milling operation?

• A. Width of cut × depth of cut × table feed per minute
• B. Spindle speed × chip load
• C. Depth of cut × width of cut × feed per revolution
• D. RPM × feed per revolution

Answer: (A)

Material removal rate is the amount of material removed per unit of time, i.e., a volume per minute. In milling, the volume being cut each minute is the cross-sectional area of the cut (how wide the cut is times how deep it goes) multiplied by how fast the workpiece moves under the cutter. So you multiply width of cut by depth of cut by table feed per minute. That combination directly gives cubic inches (or cubic centimeters) per minute, which is the MRR.

For example, with a width of cut of 0.5 inch, a depth of cut of 0.2 inch, and a table feed of 15 inches per minute, the MRR is 0.5 × 0.2 × 15 = 1.5 cubic inches per minute.

The other approaches don’t neatly account for all three factors needed to get a volume-per-time measure: they either miss one dimension (width or depth), or rely on rpm/chip load without tying them to the cross-sectional cut area and the actual feed rate.