What is Knurling? Learn how to make knurling engravings on metal! The Knurling is a manufacturing process, typically conducted on a lathe, process for producing indentations on a part of a workpiece. This interesting process allows hands/fingers to get a better grip on the knurled object than would be provided by the originally smooth metal surface. Knurling has a wide variety of applications where patterns of lines, crosses, and cuts are made on the surface of metal.