3-D printing is a way to produce parts without tooling and to create shapes that are difficult or impossible to create via other production methods, allowing for assembly consolidation and other operational and product performance benefits. Hundreds of companies produce 3-D printers that print plastic parts. A smaller number of companies, in the dozens, produce 3-D printers that print metal parts. However, to date, there hasn’t been a way to mass produce metal parts.
Desktop Metal Inc. is one of the few companies bringing to market a new generation of 3-D metal printers that can mass produce parts. These printers are going to revolutionize how metal parts are made.
“In additive manufacturing, there are literally more than 500 companies with different technologies, including ones that print metal,” says Ilya Mirman, chief marketing officer, Desktop Metal Inc. “These technologies are aimed almost exclusively toward designers and engineers in the early stages of the manufacturing product design process. Other successful applications are fixtures, jigs and tooling for the manufacturing environment; these are typically parts needed in low volumes to keep the factory floor running.
We offer those capabilities, as well, but we’re also focusing on delivering ways to mass produce metal parts.”
Today, laser powder bed fusion is the dominant 3-D metal printing technology used worldwide. It is a mature technology that is more than 25 years old.
“Laser powder bed fusion is a well-defined and understood process,” Mirman says. “The problem is that it’s just too expensive and slow for mass production. It can be used to produce parts where cost is essentially no object, such as a defense or medical application, but at Desktop Metal we’re trying to develop a new way to mass produce metal parts that is cost effective.”
The technology that Desktop Metal uses is called binder jetting, a 3-D printing technique that lends itself to mass production. Mirman notes there are four or five other companies working to ensure that binder jetting emerges as the viable 3-D metal printing approach to mass production.
“3-D metal printing for mass production of actual parts is a reality now and is breaking out this year,” he says.
During the binder jetting process, for each layer, the printer spreads metal powder across the build bed and precisely jets a binding agent to bond loose powder and define the part geometry. Layer by layer, powder and binder are deposited until the entire build volume is packed with bound parts and surrounding loose powder.
When a build is finished, the completed build box is moved to a depowdering station where loose powder is removed. Depowdered parts are loaded into an industrial furnace where they are heated to temperatures near melting. The binder evaporates, and through solid-state diffusion bonding, the metal particles fuse together and form fully dense metal parts.
Binder jetting can effectively arrive at a geometry up to 100 times faster than laser powder bed fusion, which starts with a thin layer of metal powder that is melted with a laser to form a part layer by layer.
To make the 3-D metal printing process available for mass production, a number of technologies had to mature and come together.
“It started about 30 years ago with plastic parts, but today there is more infrastructure in place,” Mirman says. “Now, software tools are available that can create the interesting geometries that can’t be manufactured any other way, and other processes are maturing, as well.”
But it’s not just the process that has to be mature; the material properties have to be good enough, too. Desktop Metal has chosen a printing approach based on metal injection molding (MIM), which is a well-understood, broad-based powder metallurgy process. There are more than 100 alloys that can be metal injection molded.
Using the same low-cost powders used in the MIM industry allows customers access to an established powder supply chain with the scale required to support mass 3-D production with a variety of readily usable alloys. Currently, the most commonly used materials for Desktop Metal are 4140 chromoly steel, 316L and 17-4 PH stainless steel, and H13 tool steel.
Quality is another reason 3-D metal printing for mass production hasn’t been more widespread to date. It’s critical that parts are metallurgically sound but the metallurgy and geometric precision wasn’t more acceptable until recently.
“Up until a few years ago, there was no way to mass produce parts with the adequate accuracy and surface characteristics that are needed,” Mirman says. “But now the precision is comparable to a fine casting and it’s a viable way to mass produce metal parts.”
Good candidates for mass production are parts with complex geometries and parts that are expensive to make via conventional methods, such as casting, machining and stamping, that require custom setups or custom tooling.
Along with complex geometries comes a part consolidation benefit. 3-D printing allows a lot of design freedom compared with conventional manufacturing methods. An assembly of several components can often be consolidated into one printed part.
“If you can go from say five parts to one, which eliminates many supply chain challenges such as bills of materials, procurement lead times, storage and assembly, that is a giant win for manufacturing,” Mirman says.
Customization is another benefit of 3-D printing. With 3-D printing, the user can literally print the design on demand, which means they can match the production rate to the demand and even have customization on the fly.
“This truly transforms supply chain challenges,” Mirman says. “Shops can locate the printer right where they are doing production and print what they need on demand. This compresses a lot of the complexity of the supply chain. So this is yet another factor that allows 3-D metal printing to penetrate into mass production.”
Not every part is a consideration for mass production using 3-D metal printing. Poor candidates are parts that are low cost, easy to manufacture and have a set design without any changes.
“If a part is easy to make and has a simple design, and if the production process you have been using is good enough,” Mirman says, “it’s probably not worth bringing in a new technology, particularly if the tooling already exists and the cost has been amortized across a large volume of parts.
“One of the drawbacks to any substantially new technology is that it’s not a trivial process to learn,” he adds. “To bring in one of our Shop Systems or Production Systems to make a few hundred parts a week up to millions of parts a year is going to require learning some new skills and not to just make one part but to set up a whole production line.”
Every manufacturing process has its own capabilities and limitations and 3-D printing is no different. Therefore, it’s important for shops to understand its strengths in the context of their business and what they are producing. Mirman notes some pitfalls to avoid.
“I often see that the first thing a customer goes to print is something they already make,” he says. “They already have the equipment and the process down pat to make that part. While they might be able to make it cheaper, they aren’t taking full advantage of the 3-D printer. They need to find parts for the new process. They are not going to get as big a win from printing a part they are already producing successfully another way.
“It has to be a breakthrough, productivity-wise,” he continues. “The capital expense for one of our mass production systems is around $300,000 to $400,000. For a mid-size shop doing $10 million in revenue per year, that is a big investment. So it has to make sense with enough volume so the shop can produce several hundred thousand dollars of additional revenue with it.”
Mirman adds that the company is seeing customers eliminating four or five other pieces of equipment by adding a 3-D printing setup because it removes the need to do assembly or secondary processes.
“Today, the entire additive manufacturing industry is approximately $12 billion, which is sizable but only a small drop in the manufacturing industry sector bucket,” he concludes. “We’re in the middle of a transformation of manufacturing. Ten years from now, I believe a great deal of parts are going to be mass produced with 3-D metal printing.”