About CNC

A very brief guide for those who are new to CNC


CNC stands for Computer Numerical Control and is a mechanism for the control of machines by computer systems.

It was preceded by NC which stands for Numerical Control where the machines were effectively 'hard wired' to produce one specific part, the computer only being used for such things as tool compensation calculations and for editing.

What follows is a (brief) explanation of how a typical Part is manufactured using a CNC router.

Firstly the part must be designed. This is usually done using a CAD program.

The output of the CAD program is then converted via a CAM program into a Toolpath. The toolpath describes where and in what sequence material from the Stock should be removed in order to leave the part.

The toolpath must then be processed via a POST which creates machine specific G-Code.

The g-code is then fed through the G-Code interpreter which sends motion control commands to the Motion-controller[1]

The motion controller then sends control signals to the axes Motor-drivers which in turn send the appropriate control signals to the motors.

The motors of course move the axes and hence control the movement of the Spindle which powers the tool through the stock.

At the end of this process you're left with your part and a lot of chips.


[1] Some motion controllers are hardware based but in the case of smaller CNC systems, more often than not they are software based and run on a PC. In the latter case the G-code interpreter and motion-controller are often combined as one piece of software.


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