What does CCMT stand for?

CCMT is the ISO designation for one of the most common indexable inserts. CCMT inserts are usually carbide inserts, though ceramic and high speed steel inserts are available (though rarer and less available than tungsten carbide). The four letters designate the shape, relief angle, tolerance and fixing type of the insert.

C - 80 degree diamond/rhombus

C - 7 degree relief angle

M - M class Tolerance

T - Countersunk hole for screw fixing

These 4 letters are proceeded by a numerical string indicating the size of the cutting insert and the radius of the cutting tip. For example CCMT060204 is an insert with a 6mm cutting edge, 2mm in thickness with a 0.4mm cutting radius.

CCMT 09t308 would be an insert with a 9mm cutting edge, 3mm thick with a 0.8mm tip radius. The "t" stands for "thickness".

What is a CCMT insert used for?

CCMT inserts are most commonly used for turning, facing and boring operations. This is because the 80 degree shape provides a slight clearance on every cutting edge, allowing enough clearance to cut cleanly without scraping but not so much that the rigidity of the cutter is compromised. 

This makes it suitable for roughing and interrupted cutting, but not more precise operations like profiling.

What is the angle of a CCMT insert?

CCMT inserts are an 80 degree rhomboid with a 6 degree relief angle. The relief angle, like the overall shape, is suited to give just enough clearance to cut cleanly, but with enough support to be capable of robust cutting.