What is the purpose of a knurling tool on a metal lathe?

• A. To cut threads
• B. To produce a gripping pattern on the surface
• C. To polish the surface
• D. To drill holes

Answer: (B)

Knurling creates a textured grip on a metal surface by pressing a patterned tool against a rotating workpiece in the lathe. The knurling tool uses hardened rollers to deform the surface, leaving a regular diamond or straight pattern. This raised pattern increases friction and makes it much easier to hold or turn the part, especially on handles, knobs, or shafts. It’s a cold-working operation, so no material is removed—just shaped to roughen the surface for better grip. This is why it’s used specifically to improve grip, rather than for cutting threads, polishing, or drilling holes.