Power Requirements:

Power requirements for any cutting procedure should be known in advance, and must always be lower than the available machine tool power. Power (P_c) needed for cutting procedure is given by Equation (1).

P_c = F_c . V_c                                          ---------------- (1)

Here, F_c is cutting force and V_c is cutting velocity. This power is mainly uses in chip formation in the primary shear deformation zone (PSDZ) and shear deformation of chip in the secondary shear deformation zone (SSDZ). Here, the friction among the tool and workpiece is supposed negligible. The power uses in secondary shear zone (Pf) and primary shear zone (Ps) might be given by Equation (2) and (3),.

P_s = F_s . V_s                                                  ---------- (2)

P_f = F. V_f                                                      ----------- (3)

Here, F_s is shear force, F is friction force, V_f is chip flow velocity and V_s is shear velocity.

Thus the total specific energy (U_t) is given by the sum of the energies needed in SSDZ (U_f)  and PSDZ (U_s) as

U_t = U_s + U_f                                     --------- (4)

Here,

U_s = F_s . V_s / b t_u V_c               ------------- (5)

U_f = F . V_f / b t_u V_c                            ----------(6)

Here, b is the width of cut and t_u is the uncut chip thickness.

The needed specific energy per unit volume removal of material based on many factors as cutting conditions (V_c, f, t_u), work material,  cutting tool conditions (sharp or dull, tool angles), friction among chip and tool, and friction among workpiece and tool.

For gross estimation of the cutting power (P_c), cutting force (F_c) might be expressed in terms of material constant (K), depth of cut (d) and feed (f) as follows:

F_c = K d ^a f _b                           ------------- (7)

here, a and b are constants and based upon the cutting conditions.