Important Formulae 

 (a) V = π DN /1000 m/min

 Where,            V = Cutting speed, m/min

                       D = Diameter of the workpiece, mm

                       N = Rotational speed of workpiece, rpm

 (b) Time for single pass

                                         t = L + L₀ / fN  min

where, L = Length of the job, mm

           L₀ = Over travel of the tool beyond the length of the job to help in tool setting, mm

           f = Feed rate, mm/rev.

[Over travel is usually 2 to 3 mm on either side]

 (c) Roughing passes

                                    d_r  = A - A_f

Where,               A = Total machining allowance, mm

                         A_f = Finish machining allowance, mm

                         d_r = Depth of cut in roughing, mm

(d) Finishing passes

                                                 d _f   = A_f

where, d_f = Depth of cut in finishing, mm

(e) Power required

                             P = ( F × V)/60 =  ((k × d × f ) × V)/60

where, P = Power, kW

          F = Cutting force, kN

          k = Constant depending in work material, N/mm² (specific cutting pressure)

          f = Feed rate mm/rev.

         d = Depth of cut, mm

         V = Cutting speed, m/min

         x, y are constants depending upon the work material.