Computer Numerical Control (CNC) machines use sophisticated computerised processes to control machining operations. They include mechanical lathes, machining centres and milling machines. There are some disadvantages to using CNC machines over traditional methods but many advantages too.
CNC machining processes are precise because they are computer controlled. Before CNC machines, similar machining processes were carried out by operatives using hand-eye coordination. This meant that every component produced was slightly different. In cases where tolerances -- the amount of allowable deviation from the specification -- were critical, this could be problematic. According to Technology Student’s V. Ryan, CNC machines offer the possibility of making any number of identical parts.
CNC machines may be complex but they are highly controllable. Some of the controllability is because of stepper motors. These work by dividing a complete rotation of the table or tool into equal steps. The CNC machine can be programmed to stop at an exact location and begin another process. This gives the programmer a great deal of control over operations and a wide choice of processing techniques. When each axis has its own motor, like Hankook’s VTB/VTC series machines, the programmer has even more control.
CNC machines are capable of working at high speed. This helps to quicken production, which lowers costs. Once a computer program has been tested with a run-through and found to be error-free, it can be run continuously. CNC machines will not make human errors to slow down production. They can be run virtually non-stop. Theoretically, CNC programs could run even faster. The physical limitations of the machine are the only restrictions.
According to Schmit Prototypes, CNC machines are safer because human operators are rarely required. Further, where human operators would take a while to learn how to produce a completely new part, in the case of CNC machines, it’s just a case of changing the programme. In terms of labour requirements, these are lower as one supervisor can run many CNC machines at a time.