Turning is a machining process that involves using a lathe to remove material from the outer diameter of a rotating workpiece. During the turning process, a cutting tool moves in a linear motion along the surface of the rotating workpiece, removing material around the circumference until the desired diameter is achieved. The main objective of turning is to reduce the workpiece diameter to the desired dimension. Turning can be done manually with a lathe, which frequently requires continuous supervision by the operator, or by an automated lathe that does not. The tools used in the turning process include single-point cutting tools to remove material from the rotating workpiece and a lathe or turning machine. The design of the turning tool varies based on the particular application. The types of lathes used for turning include turret lathes, engine lathes, and special-purpose lathes. Lathes can be manual or CNC.

The most common lathe operations are turning, facing, grooving, parting, threading, drilling, boring, knurling, and tapping. Turning is the most common lathe machining operation, and there are two types of turning operations: rough and finish. Rough turning removes a significant amount of material in one pass, while finish turning creates a smooth surface finish. Taper turning produces a taper along the axis of the workpiece, and tapers are produced by offsetting the tailstock from the center line or by using a taper attachment. Short steep tapers can be turned using a compound rest. Contour turning or profiling is used to create complex shapes on the workpiece.

In summary, turning is a machining process that involves using a lathe to remove material from the outer diameter of a rotating workpiece. The process can be done manually or by an automated lathe, and the tools used in the turning process include single-point cutting tools and a lathe or turning machine. The most common lathe operations are turning, facing, grooving, parting, threading, drilling, boring, knurling, and tapping.