# Material Removal Rate Calculator

Created by Rahul Dhari
Reviewed by Steven Wooding
Last updated: Feb 02, 2023

Our material removal rate calculator will help you determine the volume of material removed during the machining process.

Regardless of the material in use, the manufacturing of any equipment entails machining. It could be grooving to create threads (see thread calculator) or turning to create a taper (see taper calculator). During the machining process, a block of material is chipped away with a series of operations to give an object its final shape.

Such machining processes include turning, facing, milling, finishing, knurling, grooving, etc. The final shape of the object dictates the amount of material that requires removal. In turn, this parameter is a function of the speed of machining and feed rate (check out our speeds and feeds calculator to know more).

Every machining process has a different formula for material removal rate. This calculator supports the calculation of the material removal rate for turning, drilling, milling, grinding, and grooving. You can begin the process either by punching in some numbers or reading on to learn more about how to calculate the material removal rate.

## What is material removal rate?

The material removal rate (MRR) refers to the volume of material removal per unit time during the machining process. The units of material removal rate are $\text{mm}^3\text{/s}$, $\text{cm}^3\text{/min}$, or $\text{in}^3\text{/min}$. The general calculation of material removal rate is:

$\text{MRR} = \frac{W_\text{Chip} \times A_\text{Chip}}{T},$

where $W_\text{Chip}$ is the width of the chip, $A_\text{Chip}$ is the cross-sectional area of the chip, and $T$ is the time of the operation.

## Material removal rate formulae

You can use the generalized material removal rate formula to establish formulae for different operations. Our material removal rate calculator supports 5 machining operations:

1. Turning;
2. Milling;
3. Grooving;
4. Drilling; and
5. Grinding.

We will go through them individually.

## Material removal rate formula for turning

The process of reducing the diameter of a workpiece is known as the turning operation. For a cylindrical workpiece rotating along its long axis under the turning process, the material removal process happens along two axes — the longitudinal axis and its perpendicular direction.

The speed of the cutting or removal process along the longitudinal axis is feed rate or feed per revolution $(F_\mathrm{r})$. Its counterpart is the cutting speed or perpendicular speed $(V_\mathrm{c})$. The feed rate has units of distance per revolution, whereas the cutting speed has units of distance per time. It is also a function of the depth of cut $(D_\mathrm{p})$. The material removal rate (MRR) for a turning operation is:

$\mathrm{MRR} = D_\mathrm{p} F_\mathrm{r} V_\mathrm{c}.$

## Material removal rate formula for milling

During a milling operation, a rotating tool removes material from a workpiece. This operation is pretty handy for manufacturing gears. The gear teeth are obtained after removing material using the milling machine. It is a function of depth of cut (in axial $(D_\mathrm{p})$ and radial $(D_\mathrm{r})$ directions) and feed velocity$(V_\mathrm{f})$, such that the material removal rate formula for milling is:

$\mathrm{MRR} = D_\mathrm{p} D_\mathrm{r} V_\mathrm{f}.$

## Material removal rate formula for grooving

During this operation, the material is removed to obtain a narrow cut in a workpiece. It is a type of turning operation, however, where only a small part of the workpiece is machined. A typical example of a groove is the narrow channel or canal found on parts to insert O-rings. For a groove of width $(W)$, cutting speed $(V_\mathrm{c})$, and feed rate $(F_\mathrm{})$, the material removal rate is:

$\mathrm{MRR} = W F V_\mathrm{c}.$

## Material removal rate formula for drilling

A drilling operation entails cutting or removing material with a rotary cutting tool, leaving a circular-shaped hole in the material.

The material removal rate for drilling is a function of drill diameter $(D)$, cutting speed $(V_\mathrm{c})$, and feed rate $(F_\mathrm{r})$. The material removal rate formula for drilling is:

$\mathrm{MRR} = \frac{D F_\mathrm{r} V_\mathrm{c}}{4}.$

## Material removal rate formula for grinding

The grinding operation consists of using a tool with embedded abrasive particles to remove material. The particles interact with the material's surface and remove material by cutting away small chips. The grinding process results in a very smooth surface finish, although it is also helpful to roughen up surfaces. The material removal rate formula for grinding is:

$\mathrm{MRR} = W D_\mathrm{c} V,$

where:

• $W$ – Width of surface;
• $D_\mathrm{c}$ – Depth of cut; and
• $V$ – Work velocity.

## Using the material removal rate calculator

Now that you know how to calculate the material removal rate, let's use this knowledge to find the material removal rate for a turning operation.

Consider a turning operation on a cylindrical workpiece with depth of cut of $1 \ \mathrm{ mm}$, feed rate as $3 \ \mathrm{ mm/rev}$ , and cutting speed as $4 \ \mathrm{ mm/min}$.

To calculate the material removal rate for turning:

1. Select the machining operation as Turning.

2. Enter the depth of cut as $1 \ \mathrm{ mm}$.

3. Insert the feed rate as $3 \ \mathrm{ mm/rev}$.

4. Fill in the cutting speed as $4 \ \mathrm{ mm/min}$.

5. Using the material removal rate calculator for turning:

\begin{align*} \qquad \mathrm{MRR} &= D_\mathrm{p} F_\mathrm{r} V_\mathrm{c} \\ \qquad &= 1 \times 3 \times 4 \\ \qquad &= 12 \ \mathrm{mm^3 / min} \end{align*}

## FAQ

### What is material removal rate for drilling with 1 mm drill cutting at 12 mm/min and having feed rate of 5 mm?

The material removal rate is 0.25 mm³/min. Considering 1 mm drill diameter with a cutting speed of 12 mm/min and feed rate of 5 mm/rev, the material removal rate is:

MRR = 1 × 12 × 5 / 4 = 15 mm³/min.

### What is the material removal rate formula for milling?

The material removal rate formula for milling is Dp × Dr × Vf, where Dp and Dr are the depths of cut in a perpendicular direction and radial directions, respectively, and Vf is the feed velocity measured in mm/min.

### How do I calculate material removal for turning?

To calculate material removal for turning:

1. Find the feed rate, cutting speed, and depth of cut.
2. Multiply the feed rate in mm/revolution by cutting speed in mm/min.
3. Multiply the product with depth of cut in mm to obtain the material removal rate.

### How do I calculate material removal for drilling?

To calculate material removal for drilling:

1. Find the diameter of drill bit, cutting speed, and feed rate.

2. Multiply the feed rate in mm/revolution by the cutting speed in mm/min.

3. Multiply the product with the diameter of the drill bit in mm.

4. Divide the product by 4 to obtain the material removal rate.

Rahul Dhari
Operation
Turning

Depth of cut (Dp)
in
Feed rate (Fr)
in
/rev
Cutting speed (Vc)
in/min
Material removal rate (MRR)
ft³/s
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