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3D Printing vs CNC Machining – Which is the Best Option of Your Prototype?

by Josh Biggs in Tech on 16th October 2019

CNC machining and 3D printing each has its advantages. This is why 3D printing hasn’t rendered CNC machining obsolete. But when it comes to your prototype, which one is best? The answer is that it depends on the type of prototype and your needs. Both options have different applications and some things might not be possible depending on which one you choose. In this article, we’re going to outline the cases where one manufacturing process is better so you can decide which one works best for your prototype.

Turnaround Time

In general, 3D printing is better when you require a fast turnaround time. Many prototyping services can produce and deliver 3D printed parts in a few days with nothing but a CAD file.

If you want to change a design, tooling changes could mean that it will take longer to create a new iteration of the design. On the flip side, a 3D printer doesn’t require time for tooling changes before creating the next version of the design or a totally different item. If you were making a larger lot, CNC machines can be faster overall. CNC machines can run continuously without supervision once they are set up. This means they’ll make 30 to 100 items in sequence faster than a 3D printer.

However, that’s assuming there is a single 3D printer. There are prototyping firms with a large number of 3D printers that can run several parts simultaneously. Companies like RapidDirect.com can mass produce your prototypes or small production lots. RapidDirect offers both CNC and 3D printing services, so they can make your prototype by whatever method is most appropriate for your needs. They provide engineering support services, advising clients on how to improve the manufacturability or performance of the product.

They may also advise you on material selection at the early stages of design and can guide you through the process of switching to a more conventional production method. This means that they can deliver a large number of prototypes at an affordable price incredibly quickly, no matter how it is made.

Complex Geometries

CNC machines are subtractive technology. They work by carving away at the solid block of material. 3D printing works by adding material. Both can create complex geometries, and both technologies can create complex structures with high precision. However, only 3D printing allows you to make parts with massive internal voids to minimize weight. 3D printing is also the better choice if you want to minimize waste when creating a mostly open design. So, if you want more freedom as far as forms go, 3D is the way to go.

However, that doesn’t mean 3D printing is better at everything. For one CNC machining is a great option if you’re looking for great dimensional accuracy. In addition, CNC machining can work with materials that cannot be printed yet, such as wood, for instance. CNC machining also beats 3d printing when it comes to working with metals and works just as well with plastics.

Product Specifications

CNC machining is generally better for parts that will undergo immense stress or strain. CNC machining will typically use materials that can handle a heavy load. In addition, CNC machines offer more precise results usually.

CNC machines are the better choice if you need very narrow pieces or have incredibly tight tolerances. Nothing else matches the 0.01 mm tolerances. This is why CNC machining is the best choice if you’re making items for the aerospace market. CNC machining also yields much smoother final products in general.

Price

We can’t say that CNC machining or 3D printing is cheaper since the cost-benefit analysis varies so much based on lot size. If you’re making a single prototype, 3D printing is almost always cheaper. For small runs, 3D printing is generally more affordable. However, the price will vary based on the material used.

ABS plastic filament is incredibly cheap, while PEEK costs so much that CNC machining looks like a bargain. 3D printing wins if you’re making multiple iterations of the same part as you’re testing and refining a design. This makes 3D printing the clear winner if you’re making half a dozen prototypes, each slightly different from each other.

CNC machining requires set-up and programming of the tooling. This adds to the cost of a single part or small run. However, CNC machining is cost-efficient in larger runs. If you’re making 50 to 100 prototypes, CNC machining is probably the better value. Once you’re making more than a hundred items, injection molding or investment casting may be the more economical choice assuming the geometry allows for it.

Conclusion

At the end of the day, there is no one-size-fits-all manufacturing method if you want a working prototype that will fit your specifications. The right manufacturing method depends on the product dimensions, performance requirements, lot size and turnaround time.

Categories: Tech