Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process.
There are many kinds of machining operations, each of which is capable of generating a certain part geometry and surface texture.
In turning, a cutting tool with a single cutting edge is used to remove material from a rotating work piece to generate a cylindrical shape. The speed motion is provided by rotating the work piece, and the feed motion is achieved by moving the cutting tool slowly in a direction parallel to the axis of rotation of the workpiece.
Drilling is used to create a round hole. It is accomplished by a rotating tool that typically has two or four helical cutting edges. The tool is fed in a direction parallel to its axis of rotation into the work piece to form the round hole.
In boring, a tool with a single bent pointed tip is advanced into a roughly made hole in a spinning workpiece to slightly enlarge the hole and improve its accuracy. It is a fine finishing operation used in the final stages of product manufacture.
In milling, a rotating tool with multiple cutting edges is moved slowly relative to the material to generate a plane or straight surface. The direction of the feed motion is perpendicular to the tool’s axis of rotation. The speed motion is provided by the rotating milling cutter. The two basic forms of milling are:
Other conventional machining operations include shaping, planing, broaching and sawing. Also, grinding and similar abrasive operations are often included within the category of machining.