Material Removal Rate Formula

Material removal rate (MRR) is the volume of metal cut per minute. It measures how productive a cut is and feeds directly into spindle horsepower.

MRR = WOC × DOC × Feed (IPM)

What the variables mean

Symbol Meaning
MRR Material removal rate (in³/min)
WOC Width of cut / radial engagement (inches)
DOC Depth of cut / axial engagement (inches)
Feed Feed rate (inches per minute)

Worked example

A 0.25 in wide, 0.5 in deep cut at 30 IPM: MRR = 0.25 × 0.5 × 30 = 3.75 in³/min.

FAQ

Is a higher material removal rate always better? Not necessarily. MRR needs to stay within the limits of the machine’s available horsepower, the tool’s strength, and the setup’s rigidity, since pushing MRR beyond what the system can handle causes tool failure or poor finish rather than faster completion.

How does MRR relate to spindle horsepower requirements? Required spindle horsepower scales roughly with MRR for a given material’s specific cutting energy, which is why MRR is a common way to check whether a cutting parameter set exceeds a machine’s available power before running it.

Skip the arithmetic with the MRR Calculator in Feeds & Speeds.

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