Face milling

Edge contact points at entry

Tool life also changes according to how the cutting edge enters the workpiece.

The Figure below shows the condition just before the cutting edge enters a workpiece. The section to be machined is shown as the STUV parallelogram.


Contact between the cutting edge and the workpiece occurs within the STUV parallelogram. The actual cut can start from one of four points

S, T, U and V, or one of four sides. The cut can also the STUV plane completely. Contact can be shown as the following;

Point contact: S, T, U, V

Line contact: ST, TU, UV, VS

Plane contact: STUV.


The way in which the cutting edge contacts the workpiece depends heavily on the face mill cutter edge angles and engage angle (E). For S contact point, contact starts at the weakest part of the cutting edge and fracture is more than likely to occur. Therefore, it should be avoided at all times. The most desirable is U or V point contact.