CNC Defined

CNC technology was developed in the United States in the 1950's for the US Air Force by metalworking machine tool builders. It was a major advance in the ability of machines to faithfully reproduce complex part machining steps more accurately without human intervention or variability.

CNC stands for Computer Numerically Controlled. CNC always refers to how a machine operates, that is, its basic method of controlling movement. Put another way, a CNC machine uses a stream of digital information (code) from a computer to move motors and other positioning systems in order to guide a spindle over raw material.

A CNC machine uses mathematics and coordinate systems to understand and process information about what to move, to where, and how fast. Most CNC machines are able to move in three controlled directions at once. These directions are called axes (pronounced ax-ees). The axes are given simple names such as X, Y and Z (based on the Cartesian Coordinate System). The X axis is always the longest distance a machine or a part of a machine must travel. X may be the movement from front to back, Y the movement from left to right, and the Z is almost always vertical movement (normally the spindle's positioning movement up and down).

A CNC machine must be able to communicate with itself to operate. A computer numeric control unit sends position commands to motors. The motors must talk back to the control that, indeed, they have acted correctly to move the machine a given distance. The ability of CNC machines to move in three (or more) directions at once allows them to create almost any desired pattern or shape. All of this processing happens very fast.