Металл бетіне өрнек салу өнері

Patterning of metal

Knurling is a manufacturing process, typically conducted on a lathe, whereby a pattern of straight, angled or crossed lines is rolled into the material. Knurling can also refer to material that has a knurled pattern.

The terms knurl and knurled are from an earlier knur ‘knot in wood’ and the diminutive le, from Middle English knaur or knarre ‘knot in wood; twisted rock; crag’. This descends from Old English cnearra but the vowel in Middle English may have been influenced by Old Norse knǫrr ‘merchant ship’ which was known as cnearr in Old English. The modern gnarl is a back formation of gnarled which itself is first attested in Shakespeare's works and is apparently a variant of knurled.

In knurling, indentations are produced on a part of a workpiece. Knurling allows hands or fingers to get a better grip on the knurled object than would be provided by the original smooth surface. Occasionally, the knurled pattern is a series of straight ridges or a helix of "straight" ridges rather than the more usual criss cross pattern. Knurling may also be used as a repair method: because a rolled in knurled surface has raised areas surrounding the depressed areas, these raised areas can make up for wear on the part. In the days when labor was cheap and parts expensive, this repair method was feasible on pistons of internal combustion engines, where the skirt of a worn piston was expanded to the nominal size using a knurling process. As auto parts have become less expensive, knurling has become less prevalent than it once was, and is specifically discouraged by performance engine builders. Knurling can also be used when a component will be assembled into a low precision component, for example a metal pin into a plastic molding. The outer surface of the metal pin is knurled so that the raised detail "bites" into the plastic irrespective of whether the size of the hole in the plastic closely matches the diameter of the pin. Tool handles, mechanical pencils, the grips of pistols, barbell bars, the clamping surface of a motorcycle handlebar and the control knobs on electronic equipment are frequently knurled. Knurling is also used on the grips of darts and the footpegs of BMX bicycles. Knurling is also found in many surgical instruments, where it is used for instrument identification, and its ease of being brushed clean.