A machinability rating is to be determined for a new work material using the cutting speed for a 60- min tool life as the basis of comparison. For the base material (B1112 steel), test data resulted in Taylor equation parameter values of n = 0.29 and C = 500, where speed is in m/min and tool life is min. For the new material, the parameter values were n = 0.21 and C = 400. These results were obtained using cemented carbide tooling.
(a) Compute a machinability rating for the new material.
(b) Suppose the machinability criterion were the cutting speed for a 10-min tool life rather than the present criterion. Compute the machinability rating for this case.
(c) What do the results of the two calculations show about the difficulties in machinability measurement?