In a machining operation, if the generatrix and directrix both are straight lines, the surface obtained is

Two separate slab milling operations, $$1$$ and $$2,$$ are performed with identical milling cutters. The depth of cut in operation $$2$$ is twice that in operation $$1.$$ The other cutting parameters are identical. The ratio of maximum uncut chip thicknesses in operations $$1$$ and $$2$$ is ___________

Match the Machine Tools (Group A) with the probable Operations (Group B)

A steel bar $$200$$ $$mm$$ in diameter is turned at a feed of $$0.25$$ $$mm/rev$$ with a depth of cut of $$4$$ $$mm.$$ The rotational speed of the work piece is $$160$$ $$rpm.$$ The material removal rate in $$m{m^3}/s$$ is