Computer numerical control (CNC) machining and 3D printing are two of the most common processes used in manufacturing these days. Both technologies can save you a significant amount of money and a lot of time while allowing you to produce high-quality parts. 3D Printing Vs CNC Machining is a common comparison point while deciding a manufacturing solution for many manufacturers.

However, 3D printing and CNC machining have varying capabilities. It means that one may be a better choice for a specific engineering design scenario than the other.

If you’re unsure about which process is the best choice for manufacturing your product, you’ve come to the right place. This article will help you find the option that best suits your manufacturing needs. Read on for the five considerations when choosing between CNC machining and 3D printing as your manufacturing solution.

There are limited material choices for 3D printing because the technology is a fairly recent innovation. The fewer materials available are mostly due to the limitation of the 3D printers themselves. Also, some new materials are still being developed or not fully commercialized yet.

That’s why 3D printing typically utilizes resins or thermoplastics as of now. In the case of plastics, they’re an ideal material as their lower melting point makes them easy to manage, not to mention they’re cheap. The demand for this production method is growing, so one can expect that the material options for it will increase in the coming years. However, the number of suitable materials won’t be as high compared to those for other manufacturing processes. This makes employing 3D printers for a greater number of applications difficult.

On the other hand, a precision machining shop Moseys Productions and other machining companies can accommodate a much wider range of materials. Some materials compatible with CNC machining are metal alloy, acrylic, wood, and thermoplastic.

Some geometries can’t be created using CNC machining. That’s because CNC cutting tools get into contact with the workpiece from the top. It can’t access all sides of the part without rotating the part — the required repositioning results in increased processing and labour time, which can be an issue for many companies. For example, it’s challenging to create hidden features and undercuts using CNC machines.

In scenarios where you need to create parts with complex geometry, you might be better off utilizing an additive manufacturing process like 3D printing.

Minimum feature size is the smallest size of a workpiece’s feature that machining equipment can create.

In 3D printing, you can create parts with a minimum feature size between 0.25 mm and 0.88 mm. However, 3D printers can’t print parts larger than the print bed. It’s possible to print some larger parts, but you need to break them into smaller components first. Since the components get printed separately, you have to assemble them afterward, increasing the production process time. 

On the other hand, CNC machines have a minimum feature size ranging between one to three mm. That’s about four times a 3D printer’s minimum feature size. CNC machining can also produce large objects such as refrigerators.

Material compatibility, geometry, and minimum feature size—none of those are as important to businesses as lead time.

So which has a better lead time: 3D printers or CNC machines? In general, 3D printing is the better option when one of your goals is a fast turnaround time. 3D printed parts can be produced in a few days. Such printers also eliminate the need for tooling changes when creating a design’s next version or a different item, shortening the lead time even further.

However, CNC machining can be a faster process overall when making a larger lot. That’s because there’s no need for post-processing operations when using CNC machines, unlike in 3D printing. The faster lead time in CNC machining is especially true if you’re going to create more than a hundred units of identical parts. Once they’re set up, CNC machines can run continuously even without supervision. Thus, for identical parts of over 100 units, CNC machining can be significantly faster than 3D printing.

Like fast lead times, cost-effective manufacturing technology is also every product designer’s dream. The cheaper option between 3D printing and CNC machining depends so much on lot size.

Generally, 3D printing is more affordable for small runs or when you’re making only a single prototype. On the other hand, the tooling setup and programming that CNC machining requires add to the cost of a small run or a single part. However, it probably provides better value if you’re making between 50 and 100 prototypes or doing larger runs.

Maintenance for CNC machines and 3D printers has some differences. These differences can be crucial for choosing one over the other.

With CNCs, maintenance is all about moving parts and the machinery supporting them. This includes taking care of liquids such as coolants and oils, lubrication, the filters, and cleaning the surfaces from shop grime.

3D printers are complex devices requiring care and attention — from desktop models to factory assets. They have more moving parts, and their maintenance is crucial for OEE. You need to repair, clean, and/or replace parts like nozzles, extruders, lamps, printheads, build plates, etc.

3D printing and CNC machining have strengths that make them suitable for different applications. That said, there’s no one-size-fits-all manufacturing technology out there. The right process for you would depend on the product you’ll produce. Hopefully, the various factors mentioned and discussed above can help you make the correct choice.

About Manufactur3D Magazine: Manufactur3D is an online magazine on 3D printing. which publishes the latest 3D printing news, insights and analysis from all around the world. Visit our 3D Printing Education page to read more such informative articles. To stay up-to-date about the latest happenings in the 3D printing world, like us on Facebook or follow us on LinkedIn.

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