CNC milling consists of a milling machine that uses commands, or G-codes, programmed into the machine via a computer software program. Each code entered into the program has a designated function that is performed by the machine. When codes are entered into a CNC program representing a potential finished product, the mill then drills and turns along axes to cut and shape the material to match the dimensions entered into the computer.
CNC milling machines are controlled in one of two ways: by computer or via manual override. Computer programming allows the machine to make the precise cuts required,but the manual override allows a CNC machine operator to slow down or speed up or tweak the process if necessary.
There are numerous examples of products that can be created using CNC milling processes including pulleys, arms, linkages, fixtures, and valves. Often customers have a need to make a strong part from aluminum or steel to replace a weak plastic part supplied by the manufacturer, and CNC milling machines can do this.
Turning is a slightly different process compared to CNC milling. CNC turning relies upon computer-controlled machines, but creates a different end product. The process uses a single-point cutting tool that is inserted parallel to the material that will be cut. The material ( metal, plastic, etc.) is rotated at varying speeds and the cutting tool traverses the 2 axis of motion to produce cylindrical cuts with exact depths and diameters.
CNC turning can be used on the outside of material to create a tubular shape, such as a decorative brass shoulder bolt or nautical drive shaft, or it can be used on the inside of material to create a tubular cavity within the chosen material. Just like CNC milling, CNC turning is now an automated process because it can complete projects faster and with greater accuracy than turning a lathe by hand.
As mentioned, CNC turning is used to create objects with round or tubular shapes that are created from larger pieces of material. A drive shaft is a simple example of an object that could be created using CNC turning. Other examples include tubing and custom couplings for plumbing or other applications.