What is material removal rate?
The fetched Omni page defines material removal rate, or MRR, as the volume of material removed per unit time during machining. It is commonly reported in mm^3/s, cm^3/min, or in^3/min.
Material removal rate formulae
Turning: MRR = Dp x Fr x Vc
Milling: MRR = Dp x Dr x Vf
Grooving: MRR = W x Fr x Vc
Drilling: MRR = D x Fr x Vc / 4
Grinding: MRR = W x Dc x V
Source example
Omni's turning example uses 1 mm depth of cut, 3 mm/rev feed rate, and 4 mm/min cutting speed to obtain 12 mm^3/min or 0.2 mm^3/s. That exact example is loaded by default.