Breaking end mills

▶  Description of the problem

Your end mills keep breaking even though they are new and of good quality. 

▶  Possible origins

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

Stress is due to excessive milling forces (horizontally and/or vertically) which will make the end mill heat up or take shocks 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 parameters are too high or too low, excessive forces or heat will appear and the end mill will break. 

Note that for some material (metals mostly), a cooling system is also required to help dissipate the heat in the tool, but this is usually done in more advanced usage.

▶  Solution

You have to modify your chip load/depth of cut ratio to reach optimal parameter for your tool/material/machine combination.

If you don't know what it means, it is very important to understand the basics of those principles for CNC milling. Check our article Feeds & Speeds Explained.

You will also find a parameter calculator to help you and useful tips to learn milling different standard materials in our material library.