Numerical control tool programmers write programs that control machine tools.

Numerical control tool programmers review blueprints to compute the size and position of the required cuts. Cuts may be linear, angular, or curved. The programmers determine the sequence of machine operations. This includes selecting tools and determining the machine speed and feed rates.

The programmer writes the computer program the machine uses to control the machining or processing of metal or plastic. Sometimes programmers and machinists work together to write a program. Programmers run a computer simulation to determine whether the program is functioning properly. They fix problems and re-test the program until all problems are solved. Programmers may modify existing programs rather than write each program from scratch.