Knurling looks simple until you understand what’s actually happening at the material level. Unlike cutting operations that remove material, CNC knurling is usually a forming process. Hardened knurl wheels press into the surface of a rotating workpiece, plastically deforming the metal to create a repeating pattern. The material flows under pressure rather than being machined away. That distinction matters because knurling depends heavily on material properties, machine rigidity, wheel geometry, spindle speed, and feed synchronization. The most common knurl patterns are: * Straight knurls → parallel lines for grip or press fits * Diamond knurls → intersecting patterns for hand tools and knobs * Helical knurls → angled tracking patterns for specialized applications A properly executed diamond knurl requires the wheel pitch and workpiece diameter to cooperate mathematically. If the circumference does not align well with the knurl pitch, “double tracking” can occur, where the pattern o...