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

In an open die forging, a circular disc is gradually compressed between two flat plates. The exponential decay of normal stress on the flat face of the disc, from the center of the disc towards its periphery, indicates that

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?