# How To Calculate an End Mill Feed Rate

The feed rate of your solid carbide end mill affects the chip load, tool wear, and other key factors.

Explore feed rate calculations and other factors that can improve the productivity and cutting quality of your milling operation.

### Understanding End Mill Feed Rates

The feed rate of your mill, or other tooling, is calculated using the rotations per minute, number of flutes, and chip load of your milling process. You’ll need to understand these other factors before you can calculate the feed rate.

Once calculated, adjusting the feed rate can reduce chatter, increase tool lifespan and decrease surface roughness. The end mill manufacturer may have recommended feed rates, but the optimal rate can vary depending on your tooling and material.

Every rotation of your end mill cuts away a portion of the workpiece material. This portion, or chip, is measured and used to determine the optimal feed rate using an end mill or drill speed calculator.

The chip load is also called the chip thickness. The thickness is expressed in thousandths of an inch per flute, or cutting edge.

You may see the recommended chip load described as feed per rev. This stands for feed per revolution and describes the feed in thousandths of an inch.

The chip thickness can be altered when the leading edge of the tool changes. In most instances, however, the chip thickness is the distance of movement with one revolution of the end mill.

### Calculating Feed Rate

To calculate the feed rate, you’ll need to know the revolutions per minute and the tool diameter. An end mill speeds and feeds calculator can help you quickly identify the surface feet per minute with these two factors.

You can also calculate the inches per minute using the revolutions per minute and the feed. These calculations allow you to plan for a new cutting process or troubleshoot issues with tool life or cutting quality.

Of course, the feed rate can be calculated without one of these convenient calculators. Manually performing these calculations, however, can be more time-consuming than using a convenient calculation tool.

### Improving Your End Milling Process

Why should you calculate the feed rate or consider altering the toolmaker recommended rates? Adjusting the feed rate is a critical step if you’re changing the tooling, material or other factors of the end milling process.

Here are some key reasons you may wish to calculate and adjust the feed rate:

• Reduce tool chatter
• Increase milling productivity
• Improve tool lifespan
• Reduce roughness in the finished product
• Accommodate aftermarket cutting edges

You can’t expect to use the same feed rate for every tool and material. A small-diameter hole in a wood product requires a different optimal feed rate than a large-diameter hole in a steel product. Even minor speed adjustments can help improve the entire process and your bottom line.