Match the following:

A spindle speed of $$300$$ $$rpm$$ and a feed $$0.3mm/revolution$$ are chosen for longitudinal turning operation on an engine lathe. In finishing pass, roughness on the work surface can be reduced by

A moving mandrel is used in

A $$80$$ $$mm$$ thick steel plate with $$400$$ $$mm$$ width is rolled to $$40mm$$ thickness in $$4$$ passes with equal reduction in each pass, by using rolls of $$800mm$$ diameter. Assuming the plane-strain deformation, what is the minimum coefficient of friction required for unaided rolling to be possible?