I was using 0.02" solid carbide endmill to do some pcb milling. I needed 0.5mm tracks. My mill has maximum speed of 1900 rpm, which is way way too slow, but I only had 24 straight tracks to do, so I thought I'll take it nice and slowly. After all, it was just a thin layer of copper.
After doing 3 tracks, I got a little cocky and increased the feedrate and to my utter horror, the tip of the endmill just dispapeared!!
Lesson learned, albeit an expensive one ($18). I have a whole new respect for these little endmills. I can't imagine using these little bits for milling steel let alone soft metal.