Answering the Additive Manufacturing Question - To 3D Print or Not to 3D Print?

(Image courtesy of Markforged.)

Trending technologies often take the form of solutions looking for problems—just look at AI, blockchain or the Internet of Things. All three of these examples have the potential to disrupt almost every facet of our lives, but potential alone isn’t enough to justify replacing human workers, converting all your funds into the latest cryptocurrency or embedding an RFID tag into every product. Developing new technology is difficult, but deciding how to apply it can be even trickier.

The question of whether or not to use additive manufacturing (AM) for production is a perfect example. By now, the business case for 3D printing prototypes is well established, but as any manufacturing engineer knows, there’s an enormous gulf between prototyping a product and manufacturing it—just ask Tesla.

So, how do you decide whether or not to use AM to produce your next part?

“This is a central question to many of our customers and there isn't a single answer that determines when a part is right for AM,” said Nicholas Sondej, senior application engineer at Markforged. “When selecting potential applications, we look at a range of factors to scope out the limits of a virtual envelope of their application space and then refine our criteria until we find applications that fit.”

3D Printing Existing Parts

When it comes to the question of whether to switch to AM for existing parts, Sondej noted the basic economic criteria for consideration, including all-in manufacturing cost, lead time, production volume and delivery timeline.

“In general, in order to recommend AM in such a case, we need to see improvements in at least one of these categories, otherwise there wouldn't be reason to change manufacturing techniques,” Sondej said.

3D-printed valve made with Markforged's Onyx material. (Image courtesy of Markforged.)

However, these criteria are not set in stone: one might be willing to pay more to get parts faster, for example, if it would reduce unplanned downtime or get a production line up and running again.

“A small difference in part cost between a mass manufactured part and an additively manufactured one is inconsequential if the AM part can prevent a company from losing tens or hundreds of thousands of dollars per hour in lost production,” Sondej said. “This is exactly what at least one Markforged customer has done.”

Additive Manufacturing Production Volume

Of all the economic criteria listed above, production volume is likely the biggest decider in terms of whether or not AM makes sense for your part. Although 3D-printed parts are currently being produced in greater quantities than ever before, this process is still a long way from being able to compete with traditional manufacturing processes when it comes to volume production.

3D-printed welding fixture. (Image courtesy of Markforged.)

That being said, AM can support volume production indirectly via 3D-printed fixtures and tooling. In these cases, the fast turnaround and high level of customization that AM offers can easily outweigh the benefits of conventional processes, especially when you compare material properties.

“WIth Markforged's composite fiber reinforced prints we can achieve parts with tensile strengths higher than that of 6061 aluminum, and so we tend to recommend AM for parts such as tooling and fixtures which are traditionally made from aluminum or steel,” Sondej said. We can even replace stronger or harder metals, such as carbide, by incorporating hardened off-the-shelf inserts with a printed part.”

Design for Additive Manufacturing

Economic factors aside, part design generally plays the biggest role in deciding whether or not to use AM. This means that if you’re looking to 3D print an existing part, you’ll need to be prepared to redesign it.

“If you look at nearly every other manufacturing process on earth, an expert in that process would be highly skeptical of using it to produce a part that was designed for a different process, at least in any significant quantity,” Sondej noted. “It may be possible, especially with CNC machining, but in most cases, you specifically design parts to take advantage and avoid limitations of a particular process.”

High-strength 3D-printed workholding. (Image courtesy of Markforged.)

Lead time always needs to be taken into account when switching between manufacturing processes, but AM has the added consideration of being able to produce geometries that aren’t otherwise possible. Depending on your material requirements, there can be other benefits as well.

“Three particular applications come to mind from a volume perspective,” Sondej said. “Functional prototypes, production tooling and fixtures (including maintenance-related replacement tooling) and end-of-life replacement parts. We have customers doing all three of these right now with both our composite and metal printers.”

Additive Manufacturing vs. Traditional Production

There are many nuances to the decision of whether to use AM or a more traditional production method. Sondej noted the trade-offs between agility and efficiencies of scale, in particular.

“At a certain volume of production, mass production technologies will eventually become cheaper than 3D printing, but in order to achieve those efficiencies, you have to know that your part design isn't going to change before you achieve an ROI,” he said. “An expensive production die to stamp sheet metal parts isn't worth the cost if you realize your part design needs to change before it produces enough saleable parts to break even.”

In other words, if you’re working in an industry with quick model turnover or one where designs are frequently updated, AM may be a more economical solution than one requiring large upfront costs, such as injection molding.

It should be clear by now that this article only scratches the surface of using AM for production.

For more information, download our eBook: Should You Use Additive Manufacturing to Produce Your Next Part?