CNC machining is an evolution of the milling process. This something that uses rotating cutters in order to remove excess materials from a block of material, whether that is wood, metal or plastic.
There are many different work styles that use this process, as well as a milling crowd that use it as the main function. Most commonly though, this is used for creating precision-made parts to a specific size and shape requirement which is dictated by use. You can easily find out the CNC router machine at https://www.omni-cnc.com/cncrouter/.
The tolerance of CNC machining is incredible. Since machines can be almost fully automated, there is little space for human error, except in the initial planning and programming steps.
Errors will only occur if there is a problem with the metal used, if the tool has become damaged in one way or another, or if appropriate maintenance is not performed. These machines or 'mills' as they are often referred to as, are now part of machining centers where almost all functions are carried out automatically including changing tools, control, coolants, and more.
The machining of the multitasking CNC is incredibly impressive because these machines are capable of achieving a wide variety of extremely complex and extremely delicate jobs that would take a huge amount of time to manually perform.