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), 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 was the cutting speed for a 10 min tool life. Compute the machinability rating for this case.
c) What do the results of the two calculations show about the difficulties in machinability measurement?