Step 3:

Eq. (10.12) is often represented in the form

        ------------- (14)

             --------------- (15)

where, T_vm is known as tool life for minimum cost per component (while optimizing cutting speed).

In the same way, equation for tool life (T_fm) for minimum cost per component (while optimizing feed rate) can be derived.

Step 4:

Eq. (14) shows that when the cutting conditions are found in terms of the tool life (T_vm), the corresponding optimum speed (V_opt) is found from Eq. (15) where, f is given the highest possible value.