Numerical Control (NC) is the term used to describe the automation of machine tools (meaning any powered mechanical device, such as lathes or drill presses, that are typically used in the ‘machining process’ to fabricate metal components of machines) that are operated via abstractedly programmed commands encoded on a storage system, rather than being controlled manually through a system of hand wheels and levers. The development of analogue and digital computers then allowed the creation of the first Computer Numerical Control (CNC) machine tools, further revolutionizing the manufacturing process. The emergence of CNC machine tools in turn led to the development of new and more efficient manufacturing processes such as CNC machining and CNC turning.
Turning, in basic terms, is the process whereby a single pointed cutting tool is held parallel to the surface of a material (such as metal, wood, plastic or stone) which is then rotated and the cutting tool is transverse along two axes of motion in order to produce precise depths and diameters. Turning can be carried out on the outside of the material or on the inside to produce tubular components to desired specifications (in a process known as boring). Other variations of the turning process are ‘Knurling’, which is the cutting of a serrated pattern onto the surface of a part of the material to use as a hand grip. This process requires use of a special purpose knurling tool.
The turning process is typically conducted using a lathe (believed to be the oldest machine tool developed by man) and can be one of four different types: Straight Turning, Taper Turning, Profiling, or External Grooving. These processes can produce various shapes of materials such as straight, conical, grooved and curved components. However, with every turning process, there are three principal forces that have to be taken into consideration: the cutting/tangential force (supplying the energy for the cutting operation whilst acting downward on the tool tip); the axial/thrust/feed force (acting in the longitudinal direction/the feed direction of the tool); and the radial force (which acts in the radial direction and tends to push the tool away from the work piece).
The lathe used in the turning process can be operated manually. However, this requires continuous supervision by the operator whereas if the tool was controlled by a computer (such as in the process of CNC turning), constant supervision would not be necessary, allowing the process to be carried out overnight, thereby maximising output. stamping die parts