Hi....I may be wrong but I think a feed rate of 1,066 mm per minute (42"/min) is a bit high with a depth of cut at .200"
What machine are you running?
The fact that the cutter chatters is enough to vibrate it out of the collet.
If the tool chattered that bad you should have stopped the job and analysed your cutter rates.
That's 2 carbide end mills you've broken you must be in the high upper middle class income bracket or your dad owns the store.
Ian.