Breaking end mills

1. Description of the problem

You repeatably break end mills even though they are fresh and good quality. 
Often this happens when milling aluminum or comparable hard materials. 

2. Possible origins

Breaking end mills is the signs you are inducing to much stress in it. 

Stress is due excessive milling forces (horizontally and/or vertically) which will make the end mill heat up and finally break. 

Every end mill is meant to cut at a specific feed and speed depending on its own properties and the type of material you are milling. If this feed/speed ratio is not wright, excessive forces will appear and the end mill will break. 

3. Solution

Reduce your feed and/or add air cooling to keep the temperature of your end mill as low as possible. Air cooling is also strongly recommended to mill hard materials such as aluminum. 

To learn more about Feeds and speeds go check out our article Feeds & Speeds Explained. You will also find the parameters we recommend for milling on our machines.