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.
The first major advantage of CNC machining is that it improves automation, removing the need of an operator for all but a few parts of the work. CNC machines can be left unattended for hours or even days if necessary, allowing operators to focus on other tasks. This also allows for a company to retain fewer operators, thereby saving on overhead.
By removing the operator, safety is also increased, since should there be a jam or other potentially dangerous machining error, the operator will not be holding the tool and the only thing damaged will be the tool itself. CNC machines can also work much faster than human machinists, since they are faster, stronger, and do not need to take breaks. They can also be run late at night, when most of the workers have gone home, since machines do not need to worry about being sleepy or getting paid overtime.
With the removal of the operator this increases the security as, should there be any jam or dangerous machining errors an operator won't hold the tool, while the sole thing to be damaged is the machine itself.