indexable drill

[joe-w]

I use 1.125 inch indexable drill in VMC to drill some holes. The material is QT100.
I set the 1400 rpm and 1.4in./min feedrate . It works well more than 600 holes.
But yesterday just after I replaced inserts, the peripherial insert broke and drill was damaged.
Could anybody know the reason?

Thank you

[KenFoulks]

Here are some possibilities:

Material flaw
Insert:
Flawed
Dropped
Over-Tightened
Wrong Grade
Installed over chip
Coolant:
Did not come on
Was insufficient

[Delw]

Most damage to a insert drill in a mill is due to.
Dirty seat pockets when changing inserts and chips.
you could have also worn your seat out and the insert wasnt locating properly

unlike a lathe that can be off center a mill always drills on center ,which is usually the cause.

[joe-w]

Thank you, guys
It is appreciated.
Your answers are helpful