The reasons of tools easy to break and solve way:

Reason 1: The feed rate is too fast, the cutting edge is too sharp or the corner of the knife is too sharp.

Solution: Reduce the feed rate and chamfer with gold steel to passivate the cutting edge.  

Reason 2: The accuracy of the collet is too poor or the installation is not good.

Solution: Replace the chuck, or clean up the debris in the chuck. 

Reason 3: The rigidity of the fixture is too poor, and the grip is not enough.  

Solution: Replace the fixture. 

Reason 4: The shape of the workpiece is complex and there are too many dead angles.  

Solution: Change the cutting parameters and programming method. 

Reason 5: The workpiece is not installed firmly.  

Solution: Improve the fixture to ensure the stability of the workpiece. 

Reason 6: The cutting direction is incorrect.  

Solution: Generally, down milling is used for cutting