Anatomy of a CNC machine

CNC machine anatomy explained

Machinists and production floor supervisors love CNC machines. One CNC machine can replace between three and a dozen workstations in a production line. The time, money, improved output, numbers, and quality make a CNC machine every manufacturer’s dreams come true. So what is a CNC machine, what does it do, and how does it get such great results?

21st century technology built on 16th century ideas

Centuries ago, craftsmen came up with a way to make their handmade furniture, tools, utensils, and other commonly used implements easier to build and more uniform once completed. They made “jigs” that held the working material in place while the craftsman performed his tasks. Lathes, drills, and primitive routers turned out consistent sizes and better quality workpieces over and over again. Over time, technology and power came into the picture and the evolution of modern CNC machines came about. Check out our previous article for a more in-depth look at the history of CNC machines.

Definition of CNC

The term “CNC” is an acronym for “Computer Numeric Control”. Computers were in their infancy when an engineer at MIT invented the first machine controlled by computer signals in the early 1950’s. That prototype CNC machine was quickly adapted to lathes, drills, routers, and other single-function machine shop devices to produce uniformly-made workpieces without human control. As computers became more sophisticated so did the programs that ran the production machines. With the advent of Computer-aided Design (CAD) and Computer-aided Manufacturing (CAM) programs, the technology behind CNC machines took a giant leap forward. 

Axis by axis: how CNC capabilities have grown

Each direction a tool moves over a workpiece is called an “axis”. Each axis direction is given a letter designation. A tool moving from the front of the work area to the rear is called the “X-axis”. Side to side movement is the “Y-axis”. Movements up and down are called the “Z-axis”. The first modern CNC machines worked with these three-axis directions by incorporating a computer controlling the machine tool’s movement over a workpiece.

Until a few years ago, a three-axis CNC machine was all that was available until four and five-axis machines were developed. Suddenly, CNC capabilities had increased ten-fold. No longer were machining operations limited to working on the exterior surfaces of a workpiece. In the 21st Century, a CNC machine can perform work inside a workpiece.

Anatomy of a CNC machine: what parts do they have?

The parts required for CNC machine operations are a mixture of old terminology being used alongside modern techno-speak. A CNC machine has specific attributes that make it function as a single unit, including:

Drive System

Every CNC machine has motors, drive belts, pneumatic arms, and other devices used to power the tools, locate them to the exact location for machining to be accomplished, transit the tools across the work surfaces, and return the tool to the tool bin before the next tool is put to work.


The place a tool is attached to the working drive turning the tool is called the ” spindle “. Not exactly the same spindle your grandfather knew in years gone by, but the name has remained as the tool’s power connection point. The work a machinist once had connecting and disconnecting each tool to the spindle has been automated, eliminating the need for a worker and increasing productivity and safety.


The ” bed ” is the carrier a workpiece is attached to that locates the workpiece in a precise manner for machining to take place. A workpiece is attached to the bed so that it doesn’t move while being machined.


The “Part Program”, the computer coding language that tells the machine what tool to use and how to use it is the result of the Computer-aided Design ( CAD ) program constructing the workpiece on a computer. The specifications and measurements from the CAD design tell the CNC machine where and how to perform its functions.

Program Input

The instructions that control a CNC machine’s functions are a computer program that is fed into the CNC’s Machine Control Unit (MCU). The program determines which tools perform the functions needed to produce the specified production part.

Machine Control Unit 

The brain that interprets the computer commands and turns those commands into specific machine functions is called the Machine Control Unit or MCU. The input designs combined with the Part Program become the CNC machine’s directions for using the right tool to accomplish the desired cuts to the workpiece.

CNC technology is constantly advancing

As more and more attention is paid to the capabilities of CNC machining in production environments, a greater amount of productivity and sophistication is incorporated into machine functions. The ability to move inside and outside of a workpiece in any direction and with any tooling component has made CNC technology the focus of many CNC manufacturers.

Wood, plastic, metal, and new composite materials can be configured into any design. Much like modern 3D Printers, the advanced features of CNC machines make what once was considered impossible to manufacture into reality. Not sure if you need a CNC machine or a 3D printer to complete a project? Check out this article comparing 3D printers vs. CNC machines!

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