Turning is a form of machining, a material removal process used to create rotating parts by cutting away unwanted material. The turning process requires a lathe or lathe, workpiece, fixture and cutting tool. The workpiece is a pre-formed piece of material that is held in a fixture that is itself attached to the lathe and allows for high speed rotation. The tool is usually a single-point cutting tool that is also secured to the machine, although some operations use a multi-point tool. The cutting tool enters the rotating workpiece and cuts away the metal in small pieces to form the desired shape.
Turning is used to produce rotating, usually male axis symmetrical parts that have many features such as holes, slots, threads, tapers, steps of various diameters, and even contoured surfaces. Parts manufactured entirely by turning typically include a limited number of components, perhaps for prototyping, such as custom-designed shafts and fasteners. Turning is also commonly used as an auxiliary process to add or refine the characteristics of parts made using a different process. Because turning can provide high tolerances and surface finish, it is ideal for adding precision rotating features to parts whose basic shape is already formed. The results show that high efficiency as well as high accuracy can be attained by CNC turning.
Turning is a machining process in which the cutting tool, usually a non-rotating head, describes a spiral tool path by a more or less linear motion while the workpiece rotates. The axis of motion of the tool may really be a straight line, or it may be along some curve or angle, but they are essentially linear (in a non-mathematical sense). Often, the term “turning” is reserved for producing an outer surface by this cutting action, while the same basic cutting action is referred to as “boring” when applied to an inner surface (i.e., a certain type of hole). Thus, the phrase “turning and boring” classifies the larger (and essentially similar) family of processes. Cutting faces on a workpiece (i.e., surfaces perpendicular to the axis of rotation), whether with a turning tool or a boring tool, is referred to as “facing” and can be classified as a subset of both. Today, the most common type of such automation is computerized digital control, better known as CNC. (In turning, a piece of relatively hard material (such as wood, metal, plastic or stone) is rotated and the cutting tool is moved along 1, 2 or 3 axes of motion to produce precise diameters and depths. Turning can be done on the outside of a cylinder or on the inside (also known as boring) to produce tubular parts in a variety of geometries. Although now quite rare, early lathes could even be used to produce complex geometries and even platonic solids; although since the advent of CNC technology, it has become unusual to use non-computerized toolpath control for this purpose. Turning operations are usually performed on lathes, considered to be the oldest machines, and can be of four different types, such as straight, tapered, profiling or external groove turning. These types of turning operations can produce various shapes of materials such as straight, round, curved or slotted workpieces. In general, turning uses simple single point cutting tools. Each group of workpiece materials has an optimal set of tool angles that have evolved over the years. Scrap metal chips from turning operations are known as swarf (North America), or chips (UK). In some areas, they may be referred to as turning.