ADKT1505 PDTR IC 328

The shape of an insert has a major influence on the impact resistance of the carbide. 

The weakest section of a milling insert is the corner, which is exposed to constant interrupted cuts and extreme heat changes. 

Since a round insert has no corners, it is more secure than any other shape.

Consider the tremendous forces that are placed on a milling insert in a typical cut. 

As the insert enters the cut, it is subjected to a large compressive load. 

The initial contact between the cutting edge and the workpiece may be very unfavorable depending on the position of the cutter in relation to the workpiece. 

As the insert moves through the cut, the chip thickness is constantly changing, varying the radial and axial cutting forces. 

Finally, as the insert leaves the workpiece, it is subjected to tensile stresses that break down the carbide. 

The chip bending away from the insert places large tensile or "ripping" stress on the face of the carbide.