Internal gears are manufactured by

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)