Once the system is developed, it must be loaded into the CNC control. While installers could input this system directly into the controller, it might be like using a CNC machine as a very expensive typewriter. If the CNC program is developed with the help of a CAM system, it is already in the form of a text file. If the system is written by hand, it can be fed into any computer that uses a general-purpose word processor (although most companies use special CNC text editors for this purpose). In any case, the system is in the form of a text file that can be transferred directly to the CNC machine. For this purpose, a distributed numerical control (DNC) system is used.

A DNC system is simply a PC networked with one or more CNC machines. Until recently, a rather crude serial communication protocol (RS-232c) was required to transfer programs. Newer controls do have more current communication capabilities and can be networked in more traditional ways (Ethernet, etc). Aside from the method, the CNC program obviously has to be loaded into the CNC machine before it can be run.

Types of CNC machine tools
As mentioned earlier, CNC touches almost every aspect of manufacturing. Through the use of CNC, many machining processes have been improved and enhanced. Let's look at some specific areas and focus on the use of enhanced manufacturing processes with CNC machines.

In the metal removal industry:
Machining processes traditionally done on conventional machine tools can be achieved (and sometimes improved) with CNC machining centers, including countless milling (face, contour, slot, etc.), drilling, tapping, reaming, boring holes, and anti-boring. In a similar fashion, countless turning operations such as facing, boring, turning, grooving, knurling and threading are done on CNC turning centers. You'll find countless special "by-products" of both machine types, including CNC milling machines, CNC drill and tapping centers, and CNC lathes. All types of grinding operations, such as outer diameter (OD) grinding and inner diameter (ID) grinding, are also performed on CNC grinding machines. CNC has even opened up a whole new technology related to grinding. Contour grinding (grinding contours in a similar way to turning), previously impossible due to technical limitations, is now possible (almost commonplace) with CNC grinding machines.

In the metalworking industry:
In terms of manufacturing, manufacturing generally identifies operations that can be performed on a relatively thin board. Consider a steel filing cabinet. All major components are made of steel plate. These sheets are cut to size, punched in the right places, and then the sheets are bent (shaped) to their final shape. Likewise, operations commonly referred to as fabrication operations include shearing, flame or plasma cutting, stamping, laser cutting, forming and welding. Indeed, CNC touches almost every aspect of manufacturing.

CNC backgauges are often used with shears to control the length of the sheared board. CNC lasers and CNC plasma cutters are also used to bring sheet material to its final shape. CNC turret punches hold various die combinations and punches of most shapes and sizes through the plate. CNC bending machines are used to bend sheets within their final shape.

In the EDM industry:
Electrical Discharge Machining (EDM) is the process of removing metal by using an electric spark to burn it off. There are two forms of CNC EDM, vertical EDM and line EDM. Vertical EDMs require the use of electrodes (usually machined on a CNC machining center) in the shape of a cavity to be machined into the workpiece. Imagine the shape of a plastic bottle that has to be machined into a mold. Wire EDM is commonly used to create punch and die sets for die sets in the manufacturing industry. EDM is one of the lesser known CNC operations as it is closely related to making tools for use in other manufacturing processes.

in the woodworking industry
As in the metal removal industry, CNC machines are heavily used in woodworking shops. Operations include routing (similar to milling) and drilling. Many woodworking centers can accommodate multiple tools and perform multiple operations on the workpiece being machined.

Other forms of CNC machine tools
Many types of lettering and engraving systems use CNC technology. Water jet machining operates on high pressure water jets to cut sheets of material. CNC is even used to manufacture many electronic components. For example, there are CNC coil winding machines, as well as CNC terminal positioning and soldering machines.