How do integrated circuits, metal foundries’ investment casting molds, and inkjet printing heads inspire someone to invent a 3-D printing technology? For Professor Ely Sachs, that’s the story of how he came up with binder jetting metal printing, playing a huge part in inventing the whole world of 3-D printing in the process.
We know where it all led today. Binder jetting, in which layers of metal are deposited and held together with a binding agent to print a complete part, which is then heated to fuse the metal, is one of the two core technologies of Desktop Metal, the company that Sachs co-founded in 2015. The firm completed a Series E funding round this past January, and has raised a total of nearly $440 million. Key investors include Ford Motor Company and Koch Industries.
For Sachs, who received the SME Industry Achievement Award today at the RAPID + TCT 3-D printing conference in Detroit, it all began in the late 1980s at the Massachusetts Institute of Technology. “I was in my second or third year as a young faculty member at MIT,” Sachs said. (Sachs was then, and remains today, a professor of mechanical engineering at the school.) “I was doing work on process control for making integrated circuits.” That exposed him to the planar process of circuit production. “You start with a wafer of silicon, then create the patterning of the circuits by adding and subtracting material in layers,” explained Sachs.
Around the same time he got his first look at 3-D printing. “I happened to visit a company in New Hampshire that was a beta site for 3D Systems SLA [stereolithography, another 3-D printing technology],” Sachs said. “That was a fortuitous moment – I thought, I’ve got to get into that.”
Sachs – a mechanical engineer’s mechanical engineer, who greatly enjoys visiting factories and who says, “I’ve spent lots of time in machines shops, making things – that’s a real love of mine” – visited two other plants during that time period that provided additional inspiration. One was a metal foundry, where he learned that investment casting molds are made of metal powder and a binder agent. The other was an ink-jet print head maker, where he saw not only that burgeoning new printing technology, but also learned of the many product improvements they had coming soon.
With all those bits and pieces in mind, Sachs went to work. “I had discretionary funding as part of my research, I hired a student, talked with colleagues, and we came up with a bunch of ideas. Binder jet printing rose to the top because it was scalable and because I knew that there was at least a first application in metal casting.”
Sachs was convinced his new technology was a winner. But he was swimming against the tide. “When I was out trying to sell, or to raise funding, I was constantly challenged,” he said. “At the time, laser printers were ahead of ink-jets. I heard, ‘You’re betting on the wrong horse, laser’s going to win!’ all the time. I stuck with it though, because it had much better scope for not just rapid prototyping, which was the focus then, but for actual manufacturing.”
The story for Sachs from there parallels that of 3-D printing overall. “Five years in, I thought everything was going to be made with 3-D printing,” he said. “I got caught up in the enthusiasm.” He worked at it for about 12 years, went away from it for eight or ten years, then finally came back for good. During that time a transition in the business happened. “3-D printing was very gainfully employed making prototypes,” said Sachs. “It took a while for the focus to turn to production.”
It’s in full-scale manufacturing that Sachs now sees his bullishness on his technology paying off. Desktop Metal’s Production System combines binder jetting with single pass inkjet printing to deliver production speeds up to 100 times faster than laser systems and over four times faster than the closest binder jetting alternative. “Single pass is realizing the vision of high production rates with the line printer approach,” Sachs explained. “Our print heads have up to 32,000 jets, so it’s truly massively parallel printing. Our goal is to spread powder at a layer per second – we’re close, but we’re not quite there yet.”
The single biggest advantage of binder jet printing is scalability. “The limit on laser power is that you can actually evaporate the metal,” Sachs said. “That’s why you see multiple lasers being used. But there are limits to how much you can scale that up.”
The challenge in developing any new manufacturing technology is in the science of understanding the interaction of the machine and the materials. This applies to both the metal powders and the binders.
All that being said, Sachs sees a very bright future ahead. “Metal printing is really hot right now, and my expectation is that it’s just going to explode – maybe even displacing some of the polymer processes,” he said. “It’s the single biggest area of opportunity in our industry. There are environmental reasons to favor metal parts over plastic – we’ll see more and more interest in retreating from plastic in the coming years.”
But he sees the biggest opportunity in what the new technologies will be able to make. “The big potential – the most important thing – is to make things that can’t be made now. Look at past manufacturing technologies – there’s a high barrier to entry, but then the technology is around for a long time. Investment casting was invented 4,000 years ago in India, and machining is hundreds of years old.
“A new class of manufacturing doesn’t come along that often. It’s an opportunity to make products we just couldn’t make with other technologies, to make existing products less expensively, and to have a whole new way of making things.”
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