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HOW CNC OPERATES MACHINE TOOLS

Computer Numerical Control (CNC) operates machine tools in the same way a skilled operator would manually, but it is done automatically through stored program data. The operator reads the part drawing and then operates the machine slide handles to machine a part to size and shape. The accuracy of the part produced depends entirely on the skill and experience of the operator. CNC overcomes the possibilities of human error because the machine's functions are controlled by a fixed program and are not dependent on operator skill.

CNC offers almost unbelievable savings in production costs and part accuracy, and many other benefits. The following steps summarize how CNC works:

1. Numerical data may be fed into the system by stored data through a floppy disk, compact disk, or directly from a computer.

2. A translating unit reads the data and changes it into an electrical form that the machine tool can understand.

3. A memory system stores the data until it is needed.

4. Rotary resolvers or servo units (transducers) on the machine tool convert the data into the required machine movements.

5. A gaging device measures the machine movements to determine if the servo units have given the correct commands.

6. A feedback unit feeds information back from the gaging device for comparison to see that the machine has moved the required amount.

Once the program for a particular part has been checked for accuracy, it is ready to use. The program contains,...