# Spindle Speed Calculator

The spindle speed calculator will assist you in determining the appropriate **speed and feed** rates to perform any lathe or milling operation. These heavy-duty machines are the **backbone of the manufacturing industry** and are used for **material removal processes** such as **turning, facing, milling, finishing, knurling, grooving**, etc.

To perform said operations, they must operate on the **right spindle speeds** as well as **feeding rate** to maintain dimensional accuracy of the workpiece and finished product. The article explains what spindle speed is and **how to calculate spindle speed and the feed rate calculation**. After the example exercise, you'll be able to calculate spindle speed for milling or lathe operations.

## What is spindle speed? What is feed rate?

The spindle speed is defined as the **rotational speed of the spindle** of the machine. In lathe or CNC machines, the workpiece is attached to the chuck, which is attached to the spindle. Apart from the lathe, the spindle holds drill bits in the chuck, grinding wheels, and milling or shaping tools. The tool would get regular wear and tear from its interaction with the workpiece during the material removal process. The **spindle speed affects the surface finish** of the workpiece and also the **longevity of the cutting tool**.

The spindle speed `N`

, in _{s}`rpm`

, for a machined operating at cutting speed`V`

, in `m/min`

, is given by the spindle speed formula:

`N`_{s} = V * 1000 / (π * D)

where `D`

is the **diameter** of the workpiece in `mm`

. The above equation is used to calculate **spindle speed** for milling or other material removal processes. The spindle speed also affects the feed rate `F`

, in _{r}`m/min`

, for the machining operations. The feed rate is defined as the **amount of material being fed into the tool in length per unit time**. The **feed rate calculation formula** for a machine having `Z`

teeth is given by the equation:

`F`_{r} = N_{s} * F_{t} * Z

where `F`

is the feed per tooth in _{t}`mm`

.

## How to calculate feed rate and spindle speed?

To calculate spindle speed:

- Enter the
**diameter**of the part,`D`

. - Fill in the
**cutting speed**,`V`

. - The CNC spindle speed calculator will return the
**spindle speed**.

To calculate feed rate:

- Enter the
**number of teeth**,`Z`

. - Insert the
**feed per tooth**,`F`

._{t} - The spindle speed calculator will return the
**feed rate**.

## Example: Using the spindle speed calculator

Find the spindle speed for milling a steel workpiece having a diameter of 20 mm. Take cutting speed `V`

to be 5 m/min. Also, determine the feed rate for a single tooth having feed per tooth of 10 mm.

To calculate spindle speed:

- Enter the
**diameter**of the part,`D = 20 mm`

. - Fill in the
**cutting speed**,`V = 5 m/min`

. - Using the
**spindle speed formula**:

`N`_{s} = V * 1000 / (π * D)

`N`_{s} = 5 * 1000 / (π * 20) = 79.58 rpm

The above paragraph explains how to calculate the feed rate for milling. To use the feed rate calculation formula:

- Enter the
**number of teeth**,`Z = 1`

. - Insert the
**feed per tooth**,`F`

._{t}= 10 mm - The feed rate is

`F`_{r} = N_{s} * F_{t} * Z

`F`_{r} = 79.58 * 0.01 * 1 = 0.7958 m/min

## FAQ

### How do I define spindle speed?

The number of rotations per minute for the spindle is known as the spindle speed.

### How do I calculate spindle speed?

To calculate spindle speed:

**Multiply**cutting speed by 1000.**Divide**the product by the circumference of the workpiece/tool.

### What is feed rate?

It is the rate at which the workpiece is fed into the tool or vice versa. It is measured as the length of the workpiece per time.

### How do I calculate feed rate?

Feed rate can be calculated by:

**Multiply**the number of teeth with the feed length per tooth.**Multiply**that product by the spindle speed.