The Capability of Computer Numerical Control

The Capability of Computer Numerical Control

The dramatic effect computer numerical control has already had on traditional engi­neering production techniques is now well appreciated. Machines controlled in this way

are capable of working for many hours every day virtually unsupervised. They are read­ily adaptable to facilitate production of a wide range of components. Every function tra­ditionally performed by the operator of a standard machine tool can be achieved via a computer numerical control machining program.

To appreciate just how versatile computer numerical control can be, it is only neces­sary to examine very briefly the human involvement in the production of a simple com­ponent such as the one shown in Figure 1.3. The hole only is to be produced by drilling on a conventional vertical milling machine. The activities of the operator in producing the component would be as follows:

  1. Select a suitable cutting tool.
  2. Locate the cutting tool in the machine spindle.

Integrated conrol unit

From this list it can be seen that even the simplest of machining operations involves making a considerable number of decisions that influence the resulting physical activ­ity. A skilled machinist operating a conventional machine makes such decisions and takes the necessary action almost without thinking. Nevertheless, the decisions are made and the action is taken.

It is not possible to remove the human involvement totally from a machining process. No automatic control system is yet capable of making a decision in the true sense of the word. Its capability is restricted to responding to a manually or computer- prepared program, and it is during the preparation of the program that the decisions are made. Via that program the machine controller is fed with instructions that give effect to the decisions. In this way all the functions listed above, and many others not required in such a simple example of machining, may be automatically and repeatedly con­trolled. Figure 1.4 lists the elements of total machine control.