A $$600$$ $$mm$$ $$ \times \,\,30\,\,mm$$ flat surface of a plate is to be finish machined on a shaper. The plate has been fixed with the $$600$$ $$mm$$ side along the tool travel direction. If the tool over-travel at each end of the plate is $$20$$ $$mm,$$ average cutting speed is $$8$$ $$m/min,$$ feed rate is $$0.3$$ $$mm/stroke$$ and the ratio of return time to cutting time of the tool is $$1:2,$$ the time required for machining will be

Through holes of $$10$$ $$mm$$ diameter are to be drilled in steel plate of $$20$$ $$mm$$ thickness. Drill spindle speed is $$300$$ $$rpm,$$ feed $$0.2$$ $$mm/rev$$ and drill point angle is $${120^0}.$$ Assuming drill over travel of $$2mm$$ the time for producing a hole will be

The time taken to drill a hole though a $$25$$ $$mm$$ thick plate with the drill rotating at $$300$$ $$rpm$$ and moving at a feed rate of $$0.25$$ $$mm$$/revolution is

The abrasive material used in grinding wheel selected for grinding of ferrous alloys is