Specific cutting force

For power, torque and cutting force calculations, the specific cutting force, or k_c1, is used. It can be explained as the force, F_c, in the cutting direction (see picture), needed to cut a chip area of 1 mm that has a thickness of 1 mm. The k_c1 value is different for the six material groups, and also varies within each group.

The k_c1 value is valid for a neutral insert with a rake angle, γ0, = 0°; other values must be considered to compensate for this. For example, if the rake angle is more positive than 0 degrees, the actual k_c value will decrease.

How to calculate specific cutting force (k_c) (N/mm)

If the actual chip thickness, h_m, is, for example, 0.3 mm, the k_c value will be higher, see diagram. When the actual k_c value is defined, the power requirement can be calculated accordingly:

Net power requirement (P_c) (kW)