What is CNC Machining: Key Concepts & What to Look for in a Machine Shop
Organizations across industries can enhance their manufacturing processes by leveraging computer-numerical control (CNC) machining. The objective of CNC machining is to create a prototype by cutting a block of material into a specific shape.
CNC machining boasts both financial and production advantages over manufacturing alternatives like conventional machining and 3D printing. It is more cost-effective, more accurate, and a faster process overall.
But the appeal of the process doesn’t end there. Rather than relying on live operators to control the manufacturing functions, CNC machining features pre-programmed software and consoles that oversee the movement of the factory tools at play. The process can be deployed to monitor a broad range of machinery—including but not limited to grinders, mills, and routers—through a specific set of prompts.
CNC machining is especially useful because the manufacturing industry tends to use large quantities of materials, which come in complex shapes and a variety of sizes. Many CNC machines include multiple axes that can accommodate different angles and difficult-to-cut materials.
Developed in the 1940s, the first CNC machines used punched-paper technology instead of the digital software we see today. That said, the process has consistently produced large-scale results with great precision, no matter the application. The computerization component of CNC machining guarantees comprehensive, consistent outcomes.
I. How Does CNC Machining Work?
CNC machining is common in projects that require a high level of precision and repetition. The process can accommodate 3D shapes that—in many cases—are too complex to create via conventional machining. The instructions are written in G-code, which is generated using a form of CAD or CAM software before being fed to computers.
The code is written and revised by programmers, and as such, it can be updated as needed to produce the correct prototype shape and quantity. Upon activating a CNC machining system, the desired cuts and shapes are programmed into the software and relayed to the machinery that will carry out the tasks. The pre-programmed CNC machines feature the exacting, high-speed movements required to customize the prototype.
When the program is loaded, an operator will conduct a test of the code to make sure it’s error-free. This trial run is called “cutting air,” and is meant to protect the CNC machine by reducing the risk of damage. Even the smallest mistakes involving speed or positioning can scrape the CNC machine.
To this end, while the design details are automated in CNC machining—this helps to ensure consistency throughout the production process—a design may require cutters and drills to meet the exact specifications of the prototype. (We’ll go over this in more detail shortly.) A router or spindle will then turn the cutting implement and cut the material.
As the program runs, the process can be repeated with the highest precision. Here are two things of note in terms of how CNC machining works:
1. The CNC machining process involves open- and closed-loop systems.
There are two systems used in CNC machining to manage position control. Open-loop systems run a signal in one direction from the controller to the motor of the machine. Conversely, closed-loop systems are capable of receiving feedback signals, and can therefore correct errors regarding velocity and position.
This means that with minimal force and speed, the process can run through an open-loop control. With more force and greater speed, closed-loop control is needed to oversee the pace, consistency, and precision of the CNC machine. An open-loop system is best used in small-scale projects, while a closed-loop system is ideal for industrial applications.
2. There are a number of different types of CNC machines.
Using a CNC machine, complicated cuts can be achieved in mere minutes. CNC machining is a popular way to customize prototypes made from a variety of materials, allowing the manufacturer to generate complex shapes that would be challenging or even impossible to create manually.
Basic machines tend to move in one or two axes, while more advanced machines may have up to five axes. Multi-axis machines can turn and flip the material automatically, eliminating the need for manual intervention. They are usually more accurate as well.
The different CNC machine types are as follows:
Mills are the most common type of CNC machine. Frequently used in industrial manufacturing, they rely on G-code programs and shape the end prototype by moving across the X, Y, and Z axes.
Lathes are similar to mills, only the tools operate in a circular motion. Like mills, lathes can produce complex designs that would be impossible to create with a manual machine.
- Plasma Cutters
Plasma cutters use a plasma torch to cut hard surfaces like metals. The process involves a combination of compressed-gas air and electrical arcs.
- Water Jet Cutters
Like plasma cutters, water jet cutters shape hard materials like granite and metals—this time through the high-pressure application of water. Water jet cutters offer a cooler alternative for materials that can’t withstand a high-heat process and are often used in the mining and aerospace industries.
- Electrical Discharge Machines
Also known as die-sinking or spark machines, electrical discharge machines use electrical sparks to discharge a current and remove pieces of the material to achieve the desired shape.
Both CNC machining and 3D printing are used to create prototypes from a digital file. CNC machining is considered subtractive manufacturing—that is, a process whereby three-dimensional objects are created by cutting away from a solid block of material.
Meanwhile, 3D printing is known as additive manufacturing and involves the use of digital instructions to create new layers. The process generally uses fused-deposition (FDM) software to create the product.
CNC machining offers the following benefits over 3D printing:
1. CNC machining is more precise than 3D printing.
Many CNC mills have accuracy rates of approximately 0.001 inch. In nearly all cases, CNC machines offer greater precision than 3D printers, in large part because the machines feature a higher tolerance for heat.
3D printers may produce distorted products in high heat, and as such, they cannot guarantee precision in hotter conditions. Meanwhile, CNC machining can accommodate the production of complex prototypes in a variety of shapes and sizes, in nearly any production environment.
2. CNC machining is faster than 3D printing.
CNC machines can operate around the clock when they’re properly maintained, and represent a much faster solution than 3D printing. Conversely, 3D printers may need to slow their pace to achieve the right design. They are less efficient than CNC machines when producing large quantities of prototypes.
Ultimately, CNC machines are better equipped to test prototypes because they can quickly build a design for developers to test. (It would take a 3D printer significantly longer to conduct the same test.) And the differences in speed don’t end there, because 3D printing requires extra work after the prototypes are built. In 3D printing the products must be washed, polished, and sealed before they’re available for people to use, which simply isn’t the case in CNC machining. With a CNC machine, the prototype becomes ready for use on completion of the fabrication process.
3. CNC machining is more versatile than 3D printing.
CNC machines are much more versatile than 3D printers. First of all, they feature a range of quality settings, which—in contrast to 3D printers—can create prototypes with rougher designs in some parts of the material and smooth designs in others.
The machines can also accommodate heavier materials than 3D printers, making them ideal for engines, aircraft, and other machines that require durability. In turn, most cutting tools can be used in any CNC machine, while 3D printers struggle to produce products that need to withstand extreme conditions.
Further, 3D printers cannot switch between materials—yet CNC machines can handle all kinds of materials, including soft and hardwoods, acrylic, thermoplastics, machining wax, metal alloys such as aluminum, steel, brass, and copper. Granted, different materials require different tools, but the tools involved in CNC machining can be swapped with ease.
In summary, CNC machines offer greater precision, speed, and versatility in large-scale production environments than 3D printers. When it comes to efficiency and accuracy, CNC machines offer a compelling manufacturing solution.
Companies across many industries outsource their CNC machining needs—usually to save time, money, and stress. These are just some of the industries that use precision CNC machining:
If you are involved in one of these industries—or perhaps another industry, such as publishing or hospitality, or even the military—you may have CNC machining work you would like to outsource.
You wouldn’t want to waste money investing in the wrong items or spend valuable time on a complex process when you could be focusing on your core business. By hiring a machine shop, experienced machinists will fulfill your precision machining needs for you.
When you outsource your CNC machining work, you can avoid the costly, time-consuming setup and maintenance the process entails. A company like Nexus Automation can produce exactly what you need in the right quantities as your organization works to bring its products to market.
Here are three reasons to outsource your precision CNC machining:
1. Save money.
The costs associated with in-house CNC machining are accompanied by marked operating expenses and high housing prices. For one-off or short-term projects in particular, outsourcing ought not be overlooked. Hiring a precision CNC machine shop will allow you to invest your capital where it matters most, and create a quality product as efficiently as possible.
By working with a machine shop, you can cut your CNC machining costs in the long term—specifically by not having to purchase the equipment, tools, or even the materials you need to get the job done.
2. Save time.
Hiring a CNC machining company will save you time because the shop will know exactly what resources they need to bring your project to fruition.
On the other hand, when using CNC machines in-house, you will need to make certain you have the right machinery, software, and materials to create your prototype. This is easier said than done.
Say you intend to use a CNC mill to transform aluminum into your desired shape. What you might not know is that you will need a specific set of tools and applications to produce your prototype. And if for your next prototype you intend to swap materials and use hardwood instead, you’ll need an entirely different set of tools and applications.
3. Enjoy expert support.
If you are working in-house and the CNC machining parts you’ve designed come out flawed, you’ll have to figure out a solution. However, if you’ve hired a precision machine shop to take the reins, they’ll work through any issues that arise and offer excellent customer service along the way.
When you hire a CNC machining company, you are paying for constant support, skilled labor, and tailored service. At Nexus Automation, our expert machinists have the knowledge, skills, and best practices to deliver a high-quality product in a short time period.
IV. 5 Things to Look for in a CNC Machine Shop
So we’ve discussed the benefits of outsourcing your CNC machining needs. Now let’s explore what to look for in a precision machine shop. While references and testimonials can be very helpful, and the company’s portfolio will offer deep insights into the quality of their work, there are other factors you should pay attention to when searching for a CNC machining company.
Five of these factors are as follows:
1. Variety in machines.
Does the company have the machines you need to complete your prototype? Make sure the shop you hire has the right in-house machinery—you wouldn’t want to hire one company, only to realize you need to outsource a different part of the job to another organization later down the road. If you work with both steel and plastic, for instance, search for a machine shop that is equipped to handle both materials. Nexus Automation has our clients covered in this way.
2. Organized workflow.
Make sure the CNC machine shop you hire has an organized, productive labor force. State-of-the-art equipment doesn’t mean much without a team of talented laborers. The right machine shop will include experienced machinists who are trained to work in a quality, streamlined, customer-oriented manner. At Nexus Automation, our machinists have been meticulously trained in the CNC machining process—not only do they have decades of experience, but they can also employ our cutting-edge equipment with ease.
3. Engineering capabilities.
You may create your own designs. Nonetheless, the CNC machine shop you work with should have engineering capabilities of its own. Companies should search for a supplier with extensive engineering, design, and manufacturing experience so the contractor can make improvements and define any practical limitations that may arise during the machining process. Collaboration and knowledge are key here—and an industry-leading precision machine shop like Nexus Automation will have you covered.
4. ISO certification.
Check that your CNC machine shop is ISO-certified, which will guarantee they’re equipped to provide the level of quality you deserve. Nexus Automation, for instance, features ISO 9001:2015 and ISO 13485:2016 certifications, which we believe speaks to our quality management approach. By definition, ISO certification means the machine shop exceeds all expectations in the way of quality. And at Nexus, we streamline our processes and accelerate our clients’ projects without compromising the work we deliver.
5. Capacity for quick-turn and small production runs.
Quick-turn and small production runs reflect the machine shop’s dedication, flexibility, and speed. We, at Nexus Automation, take pride in our ability to execute quickly and efficiently, no matter the project scope. Through our CNC machining processes and people, we guarantee seamless, defect-free prototypes in small volumes—delivered as fast as we can handle. Our world-class project management also includes an encrypted secure server, SolidWorks PDM, and EPICOR ERP, all of which translate to seamless integration in our clients’ supply chains and timeframes.
V. Precision Machining with Nexus Automation
If you are searching for a CNC machine shop, look no further than Nexus Automation. We are a small business—not to mention a certified minority- and woman-owned business—that works locally with clients throughout the Bay Area.
Our CNC machines are designed to fulfill a variety of custom services, ranging from machined components to entire assemblies. We guarantee quick time-to-market and compliance for even the most demanding specs, and produce sophisticated parts from a range of materials.
Not only that, but our expert machinists will ensure your custom parts fit and function exactly as you designed them. The design will remain in our system indefinitely, and can be updated at any time you choose.
Our clients—who range from early-stage startups to Fortune 500 companies in the biotechnology, pharmaceuticals, medical device, automotive, solar, semi-conductor and other industries—can meet the most stringent regulatory standards due to the ISO 9001:2015 and ISO 13485:2016 certifications we discussed previously. Being ISO-certified makes us an appealing partner in highly regulated sectors, and our focus on quality promotes stress-free international expansion.
What’s more, clients need not worry about quality audits and managing processes when they work with us. Nexus Automation will oversee every aspect of their CNC machining.
But most importantly, our CNC machine shop will create the prototype you need to your exact specifications, complete with high dimensional accuracy and superior finishing. With us by your side, you can expect reliable, safe components from a true partner.