CNC machining stands for "computer numerical control" machining. It is a relatively new process in the world of machining which allows for increased efficiency through higher levels of automation and by allowing the machine and it's computer controls to do all the work. While CNC machines are expensive and complicated, they quickly pay for themselves by reducing the workload and preventing errors.
CNC machining has a number of major advantages. It improves automation and eliminates the need for an operator for only a few tasks. CNC machines can be left alone for up to 24 hours, or even several days, allowing operators the freedom to concentrate on other tasks. Companies can also save on overhead by having fewer employees.
Safety is increased by removing an operator. In the event of a jam or other dangerous machining error the operator will no longer be holding the tool. The only thing that will be damaged is the tool itself. Because they are stronger and faster than human machinists, CNC machines can work faster than humans. Because they don't need to be tired or get overtime, they can be used late at night when most workers are gone.
CNC machining has another advantage: it produces exact results every time. A CNC machine produces the exact same result every time. Even the most skilled human operator can make minor mistakes. This is crucial in today's world of standard and interchangeable parts.