18.3 (Sl units) A series of cold rolling operations are to be used to reduce the thickness of a metal plate from 50 mm to 20 mm in a reversing

two-high mill. Roll diameter - 600 mm, and coefficient of friction between rolls and work = 0.15. The specification is that the draft is to be equal on each pass. Determine (a)minimum number of passes required, and (b) draft for each pass?