Karhennetaan

Karhennetaan is the Finnish present passive form of the verb karhentaa, meaning “to knurl.” In manufacturing, knurling refers to creating a textured pattern on a cylindrical surface to improve grip and, occasionally, appearance.

Knurling is a metalworking process that forms a patterned texture on rotating workpieces by plastic deformation rather than material removal. Hardened knurling rollers press into the surface, producing ridges in patterns such as diamond or straight lines. The choice of pattern depends on the intended grip and aesthetic. Three-roller knurling tools can produce a cross-hatched diamond pattern, while two-roller tools yield a linear texture.

Equipment and method: Knurling is typically performed on lathes or dedicated knurling machines. As the workpiece rotates, the knurling tool applies controlled pressure and moves along the length of the cylinder, shaping the surface. The resulting texture is shallow, and the depth is influenced by tool geometry, material hardness, and pressing force.

Applications: Knurled surfaces are common on tool handles, knobs, fasteners, dials, and handwheels. The added grip helps when fingers or gloves contact the surface, especially in tools and mechanical parts subjected to frequent handling.

Considerations: Knurling is not ideal for very soft materials or thin-walled components, which can crack or deform excessively. Proper material hardness, correct diameter, appropriate tool pitch, and controlled feed are important for a consistent, durable pattern.

See also: knurling.