What is CNC Machining?


CNC machining isn’t difficult to understand, and with a brief explanation and some background knowledge, anyone can make sense of the basic processes this type of manufacturing uses. If you’re like most people, however, you probably don’t know much about CNC machining because it isn’t something you encounter very often. It’s likely the majority of people who know a bit about CNC machining only do so because it’s part of their industry or because they’ve needed to interact with it in some way.

Are you looking to purchase or use fabricated metal, plastic, wood or foam? If so, it likely won’t be long before you start encountering concepts like CNC machining. Once you do, it can be difficult to discern whether or not this type of metal fabricating is right for your purposes without first possessing a basic understanding of what CNC machining is, how CNC machines work and why some businesses choose it over comparable options.

We want to help give you the background you need to make an informed decision when it comes to purchasing the fabricated metal that will be right for you. That’s why today, we’ve compiled this guide to the basics of CNC machining. By perusing this guide, we hope you’ll be ready to make the decision you need regarding your next step forward.

The Basics of CNC Machining

CNC machining is a manufacturing process where precisely programmed computer software controls the movements of factory equipment, tools and machinery. The acronym stands for “computer numerical control,” which references the fact that carefully coded computer commands control the entire machining process. CNC machine experts use these commands to operate factory machines, which in turn execute these commands to manufacture a completed product.

The primary process CNC machining improves upon is the process whereby operators would manually control every movement of the factory tools. An operator would need to stand at each factory station, physically operating the lathes and mills to create the desired final product. With CNC machining, however, these operators are no longer needed, creating a process that’s safer, faster, more efficient and often more effective.

CNC machining is compatible with an incredible range of tools. From plasma cutters and lathes to lasers and mills, machinists can dictate the movements of these and many more devices, all down to the smallest and most precise movements, to create uniform finished products.

How Do CNC Machines Work?


CNC machining is a complex process that breaks down into several different steps, all of which are crucial to achieving the finished product. If the factory or machine shop in question neglects any of these steps, the process will not work. To get a better understanding of how this process works, let’s examine it from start to finish.

1. Designing the Model

The very first step in the process of CNC machine programming is creating a model that will be the basis for the finished product. Engineers and designers will complete this process using software such as a computer-aided design (CAD) program, where they can create, manipulate and render a 3D model. Within the confines of this software program, they will create the design, tweak it, adjust and otherwise shape it until they confirm it is exactly the design they want.

Because CNC machining will eventually build this design, the software will typically not allow for the creation of anything that is beyond the limits of the machines. In other words, if an engineer tried to design anything the machines wouldn’t be capable of creating, the software would not allow it, notifying the designer that their model was unfeasible.

Once the design is complete, approved and shown to be compatible with the CNC machining technology, it’s time to move on to the next step.

2. Converting the Design

Now that the design is ready to go, the engineers need to translate it into a language the CNC machines can understand and interpret. To do this, workers will run the CAD model through a program that extracts the precise geometry of the design and converts it into a code that is compatible with the machines the engineers will then use to create the full-sized version of the design.

This extracted code is a combination of computer languages that work together to control different machine functions. Most notably, these include the programming languages commonly known as G-codes and M-codes. The G-code, also known as the geometric code, controls the bulk of the machines’ movements, including when, where and how they move as well as when they turn on and off and what paths they take to reach a specific location. The M-code, which stands for miscellaneous function and controls auxiliary functions, works to control additional movements like the replacement and removal of the machine covers at the beginning and end of the process.

After extracting this CNC program from the original design, the machine operators will load this code into the CNC machine.

3. Setting up the Machines

Before the machine operators can initiate the program and let the physical process begin, they’ll need to make sure the machines are ready and in position. That means they’ll need to add or remove all the proper and necessary attachments, move machine components into place and attach extra pieces such as drill bits and end mills. They’ll also need to perform safety checks to make sure no one and nothing is in the way of the machines.

Once the operators are sure everything is ready to work and there are no obstructions anywhere in the way, it’s time for the final step to begin.

4. Executing the Program

By initiating the program, the entire machine will begin to move. The CNC program extracted from the CAD design acts like a set of instructions, telling each machine exactly when to move and where to work to create the desired finished product.

Typically, this process involves a solid piece of material, such as a sheet of metal. The various tools and machines then work to carve, drill and cut away at this piece of metal, working to shape it into the design as dictated by the digital instructions they’re receiving from the CNC program.

What Pieces of Equipment Use CNC Programming?


We’ve already mentioned that CNC coding can control a wide range of various tools and pieces of machinery. But how far does that range extend? How many types of CNC machines are there, and what are they? It’s challenging to write a comprehensive list, as different CNC machine shops will use different tools depending on the types of products.

This list, however, includes the most common tools many CNC machining sites use.

  • Milling machines: These can either be purpose-built with the intent of using CNC machining, or retrofitted out of ordinary milling machines to be compatible with CNC technology. Either way, they perform the same function of using rotary cutters to remove sections of raw material.

  • Lathes: Lathes can also be designed specifically for CNC machining or can be retrofitted after the fact to be compatible with the new technology. In either case, their function remains the same as they cut, drill, sand and turn the material symmetrically.

  • Routers: These tools are exclusively for CNC machining and have no other function. You won’t likely find them used in any other industrial setting, as they’re incompatible with anything but CNC technology. Their purpose is to help produce parts with large dimensions smaller tools couldn’t handle, typically by cutting away at materials such as wood, metal or plastic.

  • Plasma cutters: CNC plasma cutters are those designed with the express intention of usage with CNC machining. They are quite similar in setup to CNC routers, but they don’t require quite such a heavy-duty makeup, as they don’t need to drag around a heavy tool. Instead, they use a plasma torch to cut two-dimensional shapes into sheet metal.

  • Laser cutters: Laser cutters exist outside the realm of CNC machining, but the ones we’re discussing here are those designed for exclusive use with CNC programming. They work similarly to a plasma cutter, except that they use a powerful laser to perform the cutting work, and can cut through metal, wood or plastic, depending on the exact strength of the laser used. These are a particularly essential component, so much so that APX York Sheet Metal has three of these tools used among our sister companies and us.

  • Pick-and-place machines: Just as the name suggests, these machines’ job is to pick components up, move them to another location and set them down again. They do this by using a vacuum to pick the piece up, before shifting and setting it down again in its new location. This ability to move and place tiny components is particularly crucial when building devices with a circuit board component.

Specific CNC machining services may use more components than this, or they may have fewer. It depends on what material the machine shop is working with, what they’re looking to do with the material and what type of processes will be necessary to achieve this. Nevertheless, this list represents a few of the most broadly used tools across the industry.

What Are the Benefits of Using CNC Machining Equipment?


In the grand scheme of the history of machining and industrial production, CNC machining is a relatively new development. It has existed since the 1940s when machinists would retrofit pre-existing machines to fit with the new technology. Today, most CNC machining involves machines that have been specifically designed to complement the computer technology.

Of course, if CNC machining is still relatively new, that leads us to some questions. What techniques did machinists use before CNC machining? More importantly, what makes CNC machining superior to these older methods, and what benefits does CNC machining offer that other methods do not?

1. It’s Safer

Older methods of machine operations required operators to stand at the machines themselves, physically operating them and moving the various components around. By extension, this required human operators to work next to dangerously sharp moving parts. This proximity naturally meant the risk for accidents was higher.

CNC machining eliminates this danger, as human operators do not have to be near the tools as they work. All they need to do is operate the computer controls that set the machines in motion, then watch a safe distance as the machines carry out their predetermined code to create the desired product. The risk of injury is slim to nonexistent.

2. It’s More Precise

No matter how skilled machine operators are, they’re still human, and that means that their work will likely not be as uniform and precise as that of a machine operating according to strict instructions. A human operator might produce 100 items that are all nearly identical, but close inspection will almost certainly reveal slight differences between the different objects.

A machine, on the other hand, will produce the same item every time. The only reason there might be differences between products is if there is an error in the programming or if something goes wrong with the machines. If everything goes according to plan, however, those 100 items will all be perfect copies of each other — completely uniform and exactly matching.

3. It’s Faster

When human operators are manually performing every step of the process, it takes time. CNC machining, on the other hand, allows for multiple parts to be moving at the same time and many operations to be carrying on in the same moment. Everything is automated, with no need for hesitation between one step and the next. The result is an operation that’s far faster and far more efficient than any other type of machining production.

Choose APX York Sheet Metal for Your CNC Machining Needs

CNC machining can be useful for a whole host of different industries, such as aerospace and communications. Are you part of an industry that frequently makes use of CNC machining? Are you looking for a machine shop to handle your CNC machining needs? We invite you to come and visit us here at APX York Sheet Metal.

We’re a custom sheet metal fabrication shop based out of York, Penn., where we’ve been family-owned for the past 71 years. Not only that, but some of our team members also have more than 25 years of experience in the industry, meaning we have the background and in-depth industry knowledge to provide you with the services you’re looking for. We pair this industry expertise with personalized customer service, quick turnaround times and a one-stop-shop experience where everything gets completed in-house for a CNC machining experience that gives you the individual attention you deserve.

Are you ready to get started discussing your next CNC machining project? Contact us to get the conversation started and to request a free quote for your project.