Computer numerical control (CNC) machining is a manufacturing process where material is removed from a block of raw material—the workpiece— with a computer-controlled rotating cutting tool until the desired machined part is formed.
CNC machining is one of our core digital manufacturing services here at JC Rapid. Using only the latest automation technology, CNC is ideal for our customers’ high precision machined parts. It is also generally the cheaper option (compared to additive manufacturing) as production ramps up and can be used on a variety of materials.
As a fully automated subtractive manufacturing process, CNC machining delivers:
- Fast material removal
- Tight tolerances and high precision
- Excellent for making complex geometries
- Versatile
- Suitable for many different kinds of substrates
- Unlimited volumes
- Low investment in tooling
- Fast turnaround
- Parts are full-strength
- Excellent surface finishes
- Easily customized
Let’s look closer at how CNC machining works, including what CNC programming is and how to use a CNC machine. CNC machining is commonly used to produce machined parts from a full range of metals and plastics. At JC Rapid, this includes:
- Aluminum
- Brass
- Titanium
- Stainless steel
- Common steel
- ABS
- Acetal
- HDPE & LDPE
- PEEK
Thanks to its versatility, at JC Rapid, No matter what material you use, you need absolute confidence that it conforms to your specifications and regulatory requirements. That’s why we have a best-in-class material control. We Strictly to verify all incoming stock, and provide you with a full physical analysis. It’s the only way to be sure you get exactly the quality and performance you demand.
CNC Programming
Geometry code, or G-Code, is the programming language of the CNC machine.
The control computer on a CNC machine reads the G-Code file line by line and then commands the rotating cutting tool to carry out the movements—a major upgrade from traditional milling machines that were manual and required an operator to control the movements by hand.
There are three ways to program a CNC machine:
- For very simple operations, the G-Code program can be entered manually through the MDI (manual data input) of the control computer.
- For more complex designs, a 2D or 3D model can be imported with CAM (computer-aided manufacturing) software to generate a G-code file that is then loaded into the CNC controller.
- Complex designs can also be imported as a 3D model of the machined part on CAD (computer-aided design) software. CAM software is used to specify the cutting operations to generate a G-code file which is then loaded into the CNC controller.
These front-end automation capabilities are what makes CNC machining fast and precise, allowing a high-quality part to be machined in less than a day.
CNC Mills
CNC Milling is a specific type of CNC Machining; if you would like to find out more on CNC machining, check out our in-depth guide. Computerised controls produce a custom-designed part or product of high quality and precise finish. It is favoured in many industries due to its accuracy, consistency, and ability to increase production and uniformity. The milling process starts with a CAD drawing (computer-aided design), and it is used to control the outputs of the CNC Milling machine.
CNC mills keep the workpiece stationary while the spindle and cutting tool move.
Common applications for CNC milling include jigs and fixtures.
CNC milling machines vary in their ability to work on complex designs—CNC axis machining plays a key part in the process. CNC axis machines range from 3-axis milling machines that perform simple operations to 5-axis milling machines for more sophisticated operations.
- 3-axis machining, where the three linear axes move simultaneously – X (side-to-side), Y (front-to-back), and Z (down-and-up).
- 4-axis machining, where rotation on one axis occurs simultaneously to the linear movement.
- 5-axis machining, where rotation on two separate axes occur simultaneously to the linear movement.
CNC Lathes
A computer numerical control lathe is a machine that turns material around a central spindle and stationary cutting tool. Your material’s movement is dictated by coded instructions fed through a computer rather than operated with manual labour. Multiple steps can be programmed at once, so your material doesn’t have to leave the lathe between manufacturing, guaranteeing correct placement for cuts.
A simple CNC lathe operates on 2 axes and moves the material it is cutting with a rotation. The material’s rotation is commonly called ‘turning’, so you may hear CNC lathes being referred to as CNC turning machines. Lathe machines with more than 2 axes, perhaps with an additional Y-axis or sub-spindle, will likely be nicknamed a CNC turning centre rather than a CNC turning machine.
CNC Finishes and Coatings
Once the machined part is formed, it can also undergo secondary surface treatment such as:
- 320 paper to remove cutter marks left behind from the CNC machining process
- 400 paper as a smoother alternative to 320 paper
- 600 paper for a smooth finish
- 1500 paper for an optical smooth finish
- Light bead blast for a smooth, uniform sheen
- Heavy bead blast for a light, textured appearance
- Anodizing for a protective and aesthetic coating
- Powder coat for a more durable, corrosion-resistant layer
- Chrome plating for a mirror-like finish
Strengths and Limitations of CNC Machining
As with any digital manufacturing procedure, CNC machining comes with its own set of strengths and limitations. When talking to our customers who are considering cnc machining service over 3D printing or injection molding, we discuss a number of key factors with them.
CNC machining can be used at any stage of the product development lifecycle, but it does require some post-processing. It can handle both simple and complex designs. Complex designs will cost more. CNC machining can also be expensive (cost per part) for smaller production runs as a good portion of your costs are made up of set-up charges and programming fees. If full automation is required, you will need a highly trained operator with strong programming knowledge, which adds to overall costs. However, as you work toward larger production runs, this cost levels out and CNC machining becomes a very cost-effective solution. CNC machining works well on a wide variety of materials, but keep in mind that there is often heavy material waste.
So how do you know whether CNC machining is right for you? Engaging an experienced rapid manufacturing partner like JC Rapid—with strong CNC machining experience and an engineer-centric approach—will help you make the right decision for your projects. If you have a quick turn project you need help with, submit your project to [email protected] and our team will be happy to provide expert advice. Whether your parts are simple or complex, we can handle most projects in 10 days or less.
About JC Rapid
Founded in 2002, JC Rapid is an innovator of on-demand digital manufacturing and continues to lead advances in rapid prototyping and CNC machining. We know what it takes to deliver a high-quality product on time and on budget. JC Rapid employs a team of experts in CNC machining, and takes the best approach to everything we do. Tens of thousands of product developers and engineers across the whole world trust JC Rapid to bring their products to life.
Questions? Contact our friendly sales team at [email protected]