Material Removal Rate (MRR) Calculator
Instant MRR for Turning, Milling, Drilling, Grooving & Grinding — includes formulas, examples, and optimization tips.
What is Material Removal Rate?
Material Removal Rate (MRR) is the volume of material removed per unit time during a machining operation. It’s a key metric in manufacturing that helps optimize machining processes, estimate production times, and calculate costs. Higher MRR values typically mean faster material removal but must be balanced against tool wear, surface finish requirements, and machine capabilities.
MRR Formulas by Operation
| Operation | Formula | Variables |
|---|---|---|
| Turning | MRR = π × D × f × d × N | D = diameter, f = feed, d = depth, N = RPM |
| Milling | MRR = Ap × Ae × Vf | Ap = axial depth, Ae = radial depth, Vf = feed rate |
| Drilling | MRR = (π × D² / 4) × f × N | D = diameter, f = feed, N = RPM |
| Grooving | MRR = W × f × N × Davg | W = width, f = feed, N = RPM, Davg = average diameter |
| Grinding | MRR = W × d × Vw | W = width, d = depth, Vw = work velocity |
Worked Examples
Example 1: Rough Milling Steel
Using a 20mm end mill on steel with axial depth 4mm, radial depth 4mm, feed per tooth 0.06mm, 4 flutes, and 1900 RPM:
Feed Rate = 0.06 mm/tooth × 4 teeth × 1900 RPM = 456 mm/min
MRR = 4mm × 4mm × 456 mm/min = 7,296 mm³/min
At this rate, removing 1000 mm³ would take approximately 8.2 seconds.
Example 2: Finish Turning Aluminum
Turning a 50mm aluminum rod with depth of cut 0.5mm, feed 0.15mm/rev, and 1900 RPM:
MRR = π × 50mm × 0.15mm/rev × 0.5mm × 1900 RPM = 22,384 mm³/min
At this rate, removing 1000 mm³ would take approximately 2.7 seconds.
How to Increase MRR Safely
- Gradually increase parameters – Don’t maximize all parameters at once; increase one at a time while monitoring tool wear.
- Use appropriate coolant – Proper cooling and lubrication allow higher MRR without excessive tool wear.
- Optimize toolpath strategies – Modern CAM software can optimize toolpaths for higher MRR with less tool stress.
- Select the right tool geometry – Different tool geometries perform better at different MRR levels.
- Monitor tool wear – Higher MRR accelerates tool wear; implement regular inspection schedules.
Frequently Asked Questions
Material Removal Rate (MRR) is the volume of material removed per unit time during machining operations like turning, milling, drilling, etc. It’s typically measured in mm³/min or in³/min.
For milling, MRR = Axial Depth × Radial Depth × Feed Rate. The feed rate can be calculated as Feed per Tooth × Number of Flutes × RPM.
This calculator supports both metric (mm, mm/min, mm³/min) and imperial (inches, in/min, in³/min) units. You can toggle between them using the unit switcher.
To increase MRR while maintaining tool life: optimize cutting parameters gradually, use appropriate coolants, select proper tool geometry, ensure rigid setup, and implement tool wear monitoring.