Machining is the process of cutting raw material into desired shapes and sizes by using various material removal methods and precision machine tools such as lathes, mills, bandsaws, sanders, CNC machines and turning centers. A machinist is someone who specializes in machining.
Milling is the process of using rotary cutters to remove material from a workpiece. The tool is rotated on its axis, and the workpiece is fixed. Milling is one of the most commonly used processes to precisely remove materials in the industry.
Here is a video of milling operation:
Turning on a Lathe
A lathe is a machine that rotates the workpiece on its own axis and the tool remains fixed, unlike a mill. A lathe can perform many operations such as cutting, drilling, facing, knurling, and general turning.
Here is a video on lathe operations:
CNC Machining Centers
Computer Numerical Control (CNC) milling machines or CNC machining centers are mills that are controlled by a computer. The CNC can be programmed by hand using G&M code or programmed with a Computer Aided Machining (CAM) software. More complicated and complex milling operations such as 3D tool paths are programmed using CAM. The CAM software will generate G&M code which is then sent to the CNC machine. The CNC machine is set up and ran by an operator. There are more advanced CNC machines such as five-axis/multi-axis machining centers, which have extra degrees of freedom that allow for even more complicated operations and profiles.
Here is a video on a CNC machining center:
Here is a video of multi-axis machining center operations:
CNC Lathes or CNC Turning Centers, just like CNC mills, use G&M code to operate. All the tools are fixed to a turret which is also controlled by G code. Most common CNC lathes have a Z axis and X axis only. Some advanced CNC lathes feature a Y axis and live tooling. Unlike a traditional lathe, these lathes can perform some milling operations in the middle of a turning operation such as milling a flat on a shaft.
Here is a video of a CNC turning center equipped with live tooling:
Electrical-discharge machining (EDM) is a non-conventional machining process that uses electrical discharge to obtain a highly precise shape. The material is removed by a series of recurring discharges that take place between two electrodes. The workpiece is usually separated by a dielectric liquid. This machining process is primarily used for hard metals.
Here is a video of a wire EDM in operation: