Rotary burrs
Breaking out the cutter teeth
Increase cutting speed [Vc]
Try centering
Check tool clamping
Reduce plunge of cutter into workpiece
Clogging of cutter teeth
Change tool with different geometry
Reduce tool length
Premature wear
Reduce cutting speed [Vc]
Try centering
Check tool clamping
Separating the head from the shank
Reduce cutting speed [Vc]
Cool the tool or reduce the time of use