Radial rake angle

The radial rake angle is the rake angle of the peripheral cutting edge on a cross-section to the axial centreline of the tool. The radial rake angle is an important factor that determines the cutting edge sharpness and strength. The image below shows the two types of rake angles, positive and negative.

General-purpose end mills usually have a sharp positive rake, while end mills for hardened materials tend to have a negative rake to prevent chipping.