How Do CNC Machines Work?

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Our need for machine labor is constantly evolving. As the products that we manufacture become more complex, so too must the machines that make them. As this cycle has progressed, it’s become more and more difficult for machinists to create parts for industrial machines on their own.

CNC machines present an elegant solution to this problem. They enable us to create the parts that are needed to keep our most complex machines running.

But what is a CNC machine, really? How do they work? Are they difficult to operate?

Keep reading to learn the answer to these questions and to learn everything else that you need to know about CNC machines.

What is a CNC machine, and how does it work?

Let’s start with the basics: CNC stands for Computer Numerical Control. This is one method of automating the control of machine tools. So you can use a CNC machine to perform precise cuts and other machining tasks that would be difficult to do with the human hand.

CNC machines are also used on tasks that humans are capable of doing themselves, but which would take them much longer to complete than machines.

CNC machines are given control of the tools that are needed to create a wide variety of parts. But they need instructions to know what to do. These are delivered through a programming language called G-Code.

Programmers create G-Code scripts to tell CNC machines how they should move their tools, what feed rate and spindle speed to use, and the other information that they need to know to create the right part.

Those who create these scripts usually do so using CAM software. With it, they can create a 3D or 2D model of the part that they’d like for the machine to make. Then the CAM software will automatically translate that model into a set of instructions that the CNC machine can follow.

How hard is it to use a CNC machine?

Operating a CNC machine can be easy or difficult depending on the nature of a person’s job. For example, most CNC machines today are fully automated. This means that all they need is a set of digital instructions to create the parts that you want from them.

If a person’s job is simply to input premade codes and let the machine work, then they won’t have much difficulty with learning how to use a CNC machine. The instructional process will just involve learning the machine’s controls and what needs to be done to ensure it functions optimally. This can be learned through on the job training.

But some people do more with CNC machines. Some create the 2D and 3D models that CNC machines use to create parts. This is something that you’ll need to receive a more formalized type of training to learn. If you’re interested in developing this skill, then look into certification programs that cover CAM software at your local technical school or community college.

Others perform CNC programming tasks, which relate to the writing of G-Code itself. This is covered in more depth in the next section.

Is CNC Programming Hard to Learn?

Learning the basics of CNC programming is easy enough. You just need to have some basic mathematical abilities and familiarity with the machining process. You can learn all that you need to know to start doing basic CNC programming in just a few days.

But there are also more complicated types of CNC programming. Intermediate programming can take months to learn and advanced programming tasks will take years to fully understand.

There are three major types of CNC programming that you might learn if you’re interested in doing this type of work. Here’s a look at each of them.


This is the simplest form of CNC programming. It’s usually done right at the machine itself. You can choose a pre-made set of instructions on the machine’s interface or import a pre-written script of G-code into its memory. Once you’ve done that creating the part you need is as easy as running the machine.


CAM is a type of programming that involves creating a model of what you want the machine to do. As the programmer, you set machining parameters and describe the toolpaths that you want. Then the program creates the G-code for you.


Manual programming is the most intensive, advanced type of CNC programming. It involves writing out G-codes from scratch. Manual programming has the benefit of being the most precise way to create a part with a CNC machine, but it also takes a lot of time and energy to learn.

Can you build a career out of your CNC machine expertise?

You can build a career out of CNC machine expertise. There are several ways to go about doing this. Keep reading for an overview of each of them.


Most people start as CNC machine operators. This is when you’ll learn the basics of CNC machines and what it takes to operate them. Most people with this title top out in the low-to-mid $20s per hour. But you can use the skills that you gain as a CNC machine operator to progress towards a higher-paying CNC job.


This is the second step in a common CNC machinist career path. This role involves setting up CNC machines for others to use. To do that, you’ll need to have a good understanding of something called GD&T, which stands for geometric dimensioning and tolerancing. You’ll also need to be capable of making edits through the CNC machine’s interface.

Set-up machinists make more than CNC machine operators, topping out in the higher $20s per hour.


This is the most advanced form of CNC machine operation. The role involves writing G-code that others can use to create specific parts. CNC Programmers often work for companies that have a consistent need to manufacture unique parts with CNC machines.

CNC Programmers can make in the mid-$30s per hour.


The more you learn about CNC machines, the better equipped you’ll be to instruct others on how to use them. Eventually, you’ll be skilled enough to manage a CNC shop or to open up your own. This is typically the final step in a CNC machinist’s career path.


Do I need any credentials to work with CNC machines?

You don’t necessarily need any credentials to begin working with CNC machines. But they can be useful, and you may need one or more of them if you’d like to pursue advanced positions in this field.

Here are some of the relevant credentials that are worth keeping in mind:


This credential is offered by the National Institute for Metalworking Skills (NIMS). It’s an entry-level program that teaches multi-level proficiency in CNC machining. Through it, you can learn how to:


The CCI certification teaches you how to use CAM software to begin creating your own part designs for use in CNC machines. The program will teach you how to:


This is worth pursuing if you’re interested in doing advanced programming work with CNC machines. The curriculum in CNC programming certification programs can vary, but you’ll learn what it takes to begin writing G-code scripts that can be used in CNC machines to create unique parts.

Earning your CNC programmer certificate will help you qualify for the most advanced type of CNC machine work. But you may want to begin working as a CNC machine operator before you pursue it, as doing so will make the curriculum of this certification program much easier for you to follow.

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