Glossary of Terms Used in Machining

Bed or Bedplate

A flat surface used as the basic datum in a CNC machine

Blind hole

A hole in any component or part that does not pass all the way through it


A special tool for making a hole in a component which is not round, the process known as broaching


Computer Aided Design: a process whereby components are designed as 3D models on a computer, giving files which can be imported to a machining centre to make parts


Computer Numerical Control: the process whereby a computer digitally guides the movement of machine tools


A work holding chuck that centres round bar when tightened

Cutting Speed

The surface speed of the workpiece in a lathe or machining centre

Machining Centre

A machining centre is a modern machine which will perform all operations such as milling, boring, tapping, turning and drilling.  Modern machines have sophisticated programming capabilities


A process where a part is machined using a rotary cutter which advances into the work piece to be machined.  Direction, speed and pressure may be varied


A tool which cuts threads on the inside of a suitably sized hole

Turned Parts

Turning is a machining process in which a cutting tool describes a helix toolpath by moving linearly while the workpiece rotates. This refers to external surfaces.  When a similar process is applied to internal surfaces, it is named 'boring'.