Turning is an industrial machining process that cuts into the workpiece and removes a small chip of material.
Turning involves rotating a workpiece while a cutting tool performs a straight movement in the plane. The cutting edge of the tool penetrates into the material of the workpiece and removes the part in excess (machining allowance) thus forming a chip.
Depending on the surface to be obtained, turning is divided into:
- flat (or facing) turning: flat surfaces perpendicular to the axis of rotation of the workpiece
- conical turning: conical surfaces
- cylindrical (or plain) turning: cylindrical surfaces in longitudinal direction to the axis of rotation of the workpiece
- helical turning: helical surfaces, e.g. threads, spiral groove
- shape turning (or profiling): surfaces with complex contours
Depending on the position of the tool, turning can be divided into:
- external turning: machining the exterior of workpieces
- internal turning: machining the interior of hollow workpieces
Depending on the degree of finish, the machining process is called:
- roughing: the bulk of the waste material is removed as quickly as possible. Tools capable of withstanding high stresses are used; the tolerances specified in the drawing are not considered.
- finishing: to finish the workpiece, the type and dimensions of the tools used are important; they must be carefully selected. The cutting speed and spindle speed must be adjusted to obtain a finish with the desired properties, especially roughness, and the dimensions specified in the drawing are achieved within the specified tolerances. There are various types of high-precision CNC machine tools for this type of machining.