How does a CNC work

Computer Numerical Control (CNC) machine is operated by pre-programmed list of commands, which moves parts of the machine via electrical motors. Such precisely controlled moves allows for moving tool in working space with great precision (up to 0.01mm/500mm for wood routers). The constant speed and acceleration results in quality far more superior, to one from machines operated by human.

CNC is a vast family:

  • Laser cutters
  • Plasma cutters
  • Electric discharge machines
  • Milling machines
  • Lathes
  • Routers
  • 3D printers
  • Plotters
  • Pick and place machines – robotic arms

and more..

Namely, if machine moves in controlled way between points in the space and is operated  by computer or computer program to achieve by this a goal – it is CNC machine.

Thanks to its high precision combined with speed, they became extremely popular in mass production industries. On the other hand, computerising manufacturing process made creating bespoke items of various shapes and forms easier than ever.

So what are the main components of the CNC machine in analogy to human body:

  • Control unit, which is a brain of the machine
  • Machine frame act like bones
  • Motors are muscles
  • Cables are veins and spine

Dictionary of most common phrases:

  • CAD(Computer Aided Design)

Software to create geometry, that will be further cut out on the machine or saved as technical drawings.

  • CAM (Computer Aided Manufacturing)

Software that creates paths for tools in form of numerical code, G-code. The code will be later read by the machine to cut out the part.

  • Canned cycle

Pre-programmed operation in the memory of the machine (like peck drilling), that can be called by single line command. Given only coordinates and essential parameters of the operation in the command.

  • DXF

Drawing Exchange Format – standard file format used in almost every CAD/CAM platform to save vector graphic and information.

  • G-Code

Common name for the programming language that controls CNC machines

  • M Code

A specific type of G-code designed to call sub-programs from the memory of the machine, called Macros. They are designed to perform operations like tool changes, tool measure or referencing the machine.

  • Machine Control Unit

Specially designed computer to control the machine and work with drives.

  • Machining

The controlled material-removal process with the machine, by using tools to scrap the surface of it.

  • Part Program

A series of numerical instructions used by machine control unit to move the machine or its parts and perform specific task set by engineer who programmed it.

  • Sub-Program

A smaller program that can be run inside main program. Usually used to perform specific tasks – like tool change between operations.

  • Tool-path

Imaginary line made by connecting points from part program, to represent the movement of the machine.

  • X-Axis

Usually, a horizontal axis from left to the right, when you look at the machine from the front. All movement left of a zero point is minus (-X), all movement right of the zero point is plus (+X).

  • Y-axis

Usually, a horizontal axis from front of the machine to back.  All movement further away from the zero point is plus (+Y). All movement closer than the zero point is minus (-Y).

  • Z-axis

Usually an axis that is vertically perpendicular to the X-Y zero point. All movement above the zero point is positive (+Z) while all movement below the zero point is (-Z).