| In the engineering industry many of the machines that | | | | controlled by the CNC system. |
| were once manually operated are now operated by | | | | With todays modern and complex machines, the |
| computers. Handles, levers, wheels and other types of | | | | machined part or workpiece can be moved from |
| manually operated machine components and parts | | | | machine to machine automatically with the use of |
| have been replaced by automation in one form or | | | | computer controlled robots, or human intervention, but |
| another. | | | | in either case the steps needed to produce any part is |
| The manual operation of some types of precision | | | | highly automated and the finished part will closely |
| engineering machine such as the lathe or milling | | | | match the CAD design. |
| machine are very often controlled by computer or | | | | A lathe is a machine for revolving a piece of material |
| numerically controlled. Numerical control or NC, or | | | | so as to enable a cutting tool to shape it into a |
| computer numerical control CNC refers to the | | | | component of circular cross section, or to perform a |
| automation of machine tools which are operated by | | | | screw cutting operation. Lathes which are among the |
| programmed commands that are encoded on a | | | | most important machine tools vary widely in design. |
| storage medium. | | | | The workpiece is given a rotational motion and the |
| NC machines were first built in the 1940s and were | | | | material is cut away by a tool that is given an |
| programmed by using paper tape with holes punched | | | | appropriate combination of linear (axial and radial) |
| into it at specific points. These early systems were | | | | movements. |
| soon overtaken with the augmentation of analogue | | | | Milling is a machining operation in which a workpiece is |
| and digital computers. | | | | given the desired shape by the action of a rotating |
| In CNC milling and turning, end to end component | | | | cutter, while the workpiece performs linear |
| design is automated using CAD/CAM programs. The | | | | movements. In its simplest form the milling cutter is a |
| program is put into the lathe or milling machine and the | | | | circular disc whose rim is provided with specially |
| machine is then ready for production. Some machined | | | | shaped teeth (cutting edges). The cutters are of many |
| components will generally require a number of different | | | | different kinds and shapes. The work is fed against |
| tooling applications such as drilling, reaming and tapping | | | | the teeth of the cutter, while the feed motion is |
| etc, and most modern machines will combine tools | | | | longitudinal, transverse or vertical, depending on the |
| within a single cell. This cell will move or rotate to apply | | | | type of milling machine and the nature of the work. |
| the required tooling application, and this will also be | | | | Milling machines are of the horizontal or vertical type. |