Turning
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helical toolpath by moving more or less linearly while the workpiece rotates. The tools axes of movement may be literally a linear axis, but they can also be combined into more complex motions. So turning can be either linear or contoured. Linear turning involves moving the cutting tool in a straight line parallel to the axis of rotation of the workpiece; that is, the cutting tool is fed tangentially to the workpiece. Contoured turning is a process of combining turning and feed motion to produce a certain shape on the workpiece. Examples of contoured turning include taper turning, grooving, and thread cutting.
The turning operation begins with securing the workpiece between the centers of a machine called a lathe. The elimination of material depends on a variety of factors including the type of cutting tool being used, the spindle speed, the feed rate, and depth of cut. The main types of cutting tools used for turning are single-point, grooving, threading, and form tools.
Single-point tools, also known as lathe tools, are held in a toolholder, which moves parallel to the workpiece and removes material in one direction. Single-point tools are limited in what shapes they can produce, and primarily used to produce flat or slightly contoured surfaces. Grooving tools are used to produce grooves in the face of the workpiece. They are typically used to make plastic and metal parts easier to assemble. Threading tools are used to cut threads on the outside surface of the workpiece. Form tools, such as cutting and boring tools, are used to produce irregular shapes and internal cuts on the workpiece.
The parameters for any turning process depend on the material and size of the workpiece being machined. Different types of materials require different types of tools and different cutting speeds. The depth of cut depends on how much material needs to be removed from the workpiece, and the feed rate depends on how much material is being removed in one pass. When selecting the spindle speed, it is important to consider the cutting tool material, size, and shape.
Turning processes require careful setup and monitoring to ensure the parts are machined to the correct specifications. To set up the turning process, the workpiece must be secured in the lathe and the cutting tool must be inserted into the toolholder. The correct spindle speed and feed rate must be selected before starting the machine. During the turning process, it is important to monitor the progress of the cutting tool and the workpiece to make sure everything is running smoothly. It is also important to check the surface finish of the part, as any discrepancies can adversely affect the performance of the part.
Turning is an essential machining process that is used to produce parts for many different industries. It is a versatile and reliable process that can produce components with high precision and exacting tolerances. As technology advances, new turning processes are being developed to produce components with even tighter tolerances and higher levels of accuracy.
