Tool geometry is basically referred to some specific angles or slope of the salient faces and edges of the tools at their cutting point. Rake angle and clearance angle are the most significant for all the cutting tools. The rake angle and clearance angles are illustrated with figures below.

Rake angle (Y): Angle of inclination of rake surface from reference plane.

Clearance angle ($\alpha$): Angle of inclination of clearance or flank surface from the finished surface.

The rake angle has the following function:

• It allows the chip to flow in convenient direction.

• It reduces the cutting force required to shear the metal and consequently helps to increase the tool life and reduce the power consumption. It provides keenness to the cutting edge.

• It improves surface finish.

Rake angle may be positive, or negative or even zero as shown in Figure 1.