Material Removal Rate Calculator Formula
Understand the math behind the material removal rate calculator. Each variable explained with a worked example.
Formulas Used
Material Removal Rate
mrr = depth_of_cut * width_of_cut * feed_rate / 1000MRR
mrr_mm3 = depth_of_cut * width_of_cut * feed_rateVariables
| Variable | Description | Default |
|---|---|---|
depth_of_cut | Axial Depth of Cut (ap)(mm) | 3 |
width_of_cut | Radial Width of Cut (ae)(mm) | 20 |
feed_rate | Table Feed Rate (Vf)(mm/min) | 400 |
How It Works
Material Removal Rate in Milling
MRR quantifies how fast material is being removed, which directly relates to productivity and power consumption.
Formula
MRR = ap x ae x Vf
where ap is the axial depth of cut, ae is the radial width of cut, and Vf is the table feed rate. The result in mm^3/min can be divided by 1000 for cm^3/min.
Worked Example
Milling with 3 mm depth, 20 mm width, at 400 mm/min feed.
- 01MRR = 3 x 20 x 400 = 24,000 mm^3/min
- 02MRR = 24,000 / 1000 = 24 cm^3/min
- 03For steel with specific cutting energy of 2.5 W-s/mm^3, power = 24000/60 x 2.5 = 1000 W = 1 kW at spindle.
Frequently Asked Questions
How is MRR related to machining power?
Spindle power = MRR x specific cutting energy (kc). For mild steel kc is about 2.0-2.5 W-s/mm^3, aluminium about 0.7-1.0, cast iron about 1.2-1.5. This helps verify the machine has sufficient power.
What limits the maximum MRR?
Machine spindle power, tool strength, rigidity of the setup, and required surface finish all limit MRR. Higher MRR generally means rougher surface finish and higher forces.
Is higher MRR always better?
Higher MRR improves productivity, but it must be balanced against tool life, surface quality, dimensional accuracy, and machine capabilities. Roughing passes maximise MRR; finishing passes prioritise precision.
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