(a) What do you mean by machinibility ? Discuss the factors which come into play while evaluating the machinability of any metal. Also describe machinability index.

(b) Brass components 80 mm long and 55 mm diameter were turned taking a depth of cut 1.25 mm. Using the following data find out the speed that minimizes the machining cost and determine corresponding tool life. Also estimates the cutting speed for maximum production .

Labour + Overhead charges = Rs 20/- per hour

Reconditioning cost of tool = Rs 1 per edge

Tool changing time = 6 mins

Loading and Unloading time of job = 20 sec

Feed = 0.2 mm/rev

C = 300

n = 0.25