Comparison of HSS and carbide tools

Question

Tool life equations for two tools under consideration are as follows

HSS = VT^0/2 = 150

Carbide : VT^0.3 = 250

Where V is the cutting speed in m/min and breakeven cutting speed above which the carbide tool will beneficial is

(a) 54 m/min                                  (b) 150 m/min

(c) 194 m/min                                (d) 250 m/min