RRB ALP Machinist Trade — Solved Practice Question Bank

Q: What is the key difference between a shaper and a slotter machine? Sol: A shaper's cutting tool reciprocates HORIZONTALLY across the workpiece, while a slotter's tool reciprocates VERTICALLY — making the slotter better suited for internal keyways/slots that a shaper cannot reach. Q: Why does climb (down) milling generally give a better surface finish than conventional (up) milling? Sol: In climb milling the cutter rotation direction matches the feed direction, producing a thinner-to-thicker chip that shears more cleanly, but it requires a rigid, backlash-free machine setup to avoid the workpiece being pulled into the cutter. Q: What determines the choice of abrasive type on a grinding wheel for steel vs cast iron? Sol: Aluminum oxide abrasive is generally used for steel; silicon carbide is generally used for cast iron and non-ferrous metals — matching abrasive hardness/friability to the workpiece material improves grinding efficiency.

Q: In CNC G-code, what is the difference between G00 and G01? Sol: G00 is a rapid, non-cutting positioning move; G01 is a linear cutting move performed at a specific programmed feed rate. Q: Which gear-cutting method is most efficient for high-volume production of external gears? Sol: Hobbing — a continuously rotating hob cutter generates gear teeth efficiently and is widely used for volume production. Q: What is "module" in gear terminology, and why must two meshing gears share the same value? Sol: Module = Pitch circle diameter / Number of teeth; two gears can only mesh correctly if they have the same module, since it defines tooth size and spacing.