Knurling has a wide variety of applications in the screw machine industry as many of its products have knurled surfaces. Knurling is most commonly used for decorative purposes and for serrating surfaces where component parts are locked or keyed together in unit assemblies.
The term “knurling” designates both the process and the knurled portion of the work. Knurling is obtained by displacement of the material when the knurl is pressed against the surface of a rotating work blank. Knurling tools, which have teeth of uniform pitch, are used for producing straight, diagonal or diamond knurls on cylindrical surfaces.
Cylindrical knurls are used for knurling on screw machines, automatic lathes and cylindrical die thread rolling machines. The most commonly used knurls are those which produce straight, diagonal and diamond patterns on the work. Special knurls may be used, however, to produce teeth on tapered, convex or concave surfaces. Flat knurling dies are used in reciprocating types of thread rolling machines. Diameter knurling may have either a male or female pattern. Male diamond knurls have raised points and produce a female impression. Female diamond knurls have depressed points and produce a male impression. The male diamond pattern knurling with raised points on the work is most commonly used as it can easily be produced by using two diagonal knurls-one right hand and the other left hand. Single knurls with male or female diamond patterns are also used.