How to Calculate Chip Load

Adjusting feed rate to obtain proper chip load will make your tools last longer and lead to better quality finishes.

Chip load is the measure (usually in inches or centimeters) of how much material each cutting surface removes during the cutting process with a drill or router. It is important because it also measures how far you're pushing the capabilities of your cutting surfaces. A lower chip load means you're using a lot more energy and generating a lot more heat than you may need in order to complete a job satisfactorily. Adjusting the rate your material enters the mill (the feed rate) can give you a chip load within manufacturer specifications for your tools.

Things You'll Need

• Feed rate (inches per minute)
• RPM of your bit
• Number of flutes on your bit

Instructions

1. Multiply your RPM by the number of flutes. For example, 15,000 RPM times 2 flutes gives you 30,000.

2. Divide the result from step 1 by your feed rate. For example, a feed rate of 500 inches per minute divided by 30,000 yields a chip load of 0.017 inches.

3. Optionally, convert the chip load from inches to meters by dividing it by 39.374. For example, 0.017 inches divided by 39.374 yields 0.0004 meters, or 0.04 centimeters.

References

• Vortex Tool Company, Inc.: Chip Load Chart