Material Removal Rate Calculator | MRR Tool

Material Removal Rate Calculator

The material removal rate (MRR) calculator finds how fast a machine tool removes material from a workpiece during turning. Enter the cutting speed, the feed rate, and the depth of cut, and the calculator returns the MRR in cubic millimeters per minute (mm³/min).

What is material removal rate?

Material removal rate is the volume of material a cutting tool removes per minute. Machinists use it to judge how productive a machining operation is. A higher MRR means the job finishes faster, but it can also wear out the tool sooner, use more machine power, and leave a rougher surface.

Material removal rate formula

For a turning operation, the formula is:

$\text{MRR} = v \times 1000 \times f \times d$

Where:

• v is the cutting speed, in meters per minute (m/min). This is how fast the tool moves along the surface of the workpiece.
• f is the feed rate, in millimeters per revolution (mm/rev). This is how far the tool advances for each turn of the workpiece.
• d is the depth of cut, in millimeters (mm). This is how deep the tool cuts into the material in one pass.
• 1000 converts the cutting speed from meters per minute to millimeters per minute, so the result comes out in cubic millimeters per minute (mm³/min).

Milling and drilling use different versions of this formula, since they add factors such as the number of cutting teeth or the drill diameter. This calculator covers the turning case.

How to calculate material removal rate

1. Enter the cutting speed in meters per minute.
2. Enter the feed rate in millimeters per revolution.
3. Enter the depth of cut in millimeters.
4. Read the material removal rate in cubic millimeters per minute.

All three values must be positive numbers. The calculator multiplies them together, after converting the cutting speed to millimeters per minute.

Example

A lathe cuts a steel bar with the following settings:

• Cutting speed (v): 100 m/min
• Feed rate (f): 0.2 mm/rev
• Depth of cut (d): 2 mm

First, convert the cutting speed to millimeters per minute: 100 × 1000 = 100,000 mm/min.

Then multiply all three values:

MRR = 100,000 × 0.2 × 2 = 40,000 mm³/min

A second example, with lighter cuts for a finishing pass:

• Cutting speed (v): 200 m/min
• Feed rate (f): 0.1 mm/rev
• Depth of cut (d): 0.5 mm

MRR = 200 × 1000 × 0.1 × 0.5 = 10,000 mm³/min

Why material removal rate matters

Machinists raise the cutting speed, feed rate, or depth of cut to raise the MRR and cut a job's run time. But each of those changes also raises the load on the tool and the machine. A shop has to balance a high MRR against tool wear, surface finish, vibration, and the power available on the machine. Manufacturing engineers use MRR figures to plan production schedules and estimate machining time, since the time to remove a given volume of material equals that volume divided by the MRR.

Frequently asked questions

What is material removal rate? Material removal rate (MRR) is the volume of material a cutting tool removes from a workpiece in one minute, usually measured in cubic millimeters per minute (mm³/min) or cubic inches per minute (in³/min).

What is the formula for material removal rate in turning? MRR = v × f × d, where v is cutting speed, f is feed rate, and d is depth of cut. When v is in meters per minute, multiply it by 1000 first to get the result in mm³/min.

Does a higher MRR mean better machining? Not always. A higher MRR cuts a job faster, but it also raises tool wear, heat, and cutting forces, which can hurt surface finish and shorten tool life. Shops pick an MRR that balances speed against these costs.

How do I convert MRR between metric and imperial units? Divide a value in mm³/min by 16,387.064 to get in³/min. Multiply a value in in³/min by 16,387.064 to get mm³/min.

Is the turning formula the same for milling and drilling? No. Milling and drilling use their own formulas, since they involve extra factors such as the number of cutting teeth or the tool diameter. The formula in this calculator applies to turning.

What limits the maximum MRR a machine can achieve? The main limits are the machine's available power and rigidity, the tool's material and shape, the workpiece material, and the surface finish the job requires.