The Google Advanced Technology and Projects (ATAP) lab is uniquely set up to be a one-stop-shop for bringing hardware projects to life. The lab offers a vision into the future of both products and production, but uses problem-solving approaches that any company can learn from today, from an iterative mindset at every stage of development, to a technology toolset that enables agile, creative solutions.
In one case, the team’s approach led to a process innovation that allowed them to circumvent a complex supply chain for the pre-production validation stage of an overmolded wearable device. Using Formlabs High Temp Resin, a 3D printing material with high thermal stability, they bridged the gap between prototyping and production, reducing turnaround time for a crucial component by 85% while saving over $100,000.
“We're not only investigating what products will look like in the future, but also what production looks like. Additive manufacturing really is a big part of that and ties in very directly with a lot of the projects that we work on,” said Bryan Allen, design technologist at Google ATAP who specializes in 3D printing and advanced fabrication technologies.
“I'm really excited when we can identify something new that's going on in 3D printing, a new material, a new process, and then apply it to a project pipeline in new ways that allow something to be realized more efficiently, faster, better, or more aesthetically pleasing.”
“What we had was electronics that were overmolded, then overmolded again, and that gave us this flexible, waterproof object that we could use in the wearable space,” said David Beardsley, model shop manager for the Google ATAP lab.
Overmolding is a common manufacturing process. For an overmolded part without electronics, a factory might shoot thousands of first articles at a cost of pennies per part or assembly. The ATAP team, however, was doing a second overmold over an overmolded electronic sub-assembly, a printed circuit board assembly (PCBA) with complex electronics that was sourced from another factory—so the first articles were expensive, and reliant on how quickly the first factory could produce and deliver the PCBAs.
Overmolding is an injection molding process that typically requires initial tool tuning at the factory for new parts, which are known as the first articles. These first articles might be underfilled, overfilled, or have cosmetic issues as the molding parameters are calibrated. While troubleshooting, manufacturing engineers ensure that the shutoffs are correct, the pressures are right, and all molding parameters are set correctly.
The team understood going into pre-production that the cost of first articles would be much higher than for a typical injection molded part. What they had not anticipated was the supply chain bottleneck; it took three weeks to source the overmolded electronic sub-assemblies they needed to run these tests. Beardsley needed to shorten that to ramp up production and ship product.
“You might shoot hundreds and hundreds, thousands of shots, to dial this in. The problem is when you're doing that with live electronics that have real boards that have been stuffed with real electronics and then sent off to the overmolder and then brought back, you've got this whole supply chain,” Beardsley said.
“The light went off when I was watching dollars and weeks just going in the garbage as we were trying to figure out how to dial in the tool. How do we prove this will work before we actually have to put live electronics in there?”
They needed to find a process and material that could stand in for the PCBA. The replacement had to be both dimensionally accurate and represent the exact geometry of the real sub-assembly so that fill could be characterized, and robust enough that the tool could shut off to the part without breaking or deflecting, leading to excessive flash.
“We knew we had to use a material that would withstand thousands of pounds of pressure, north of 250 °C,” Beardsley said. “We were looking for high temperature resistance, high rigidity.”
The parameters were tight. Allen decided to try 3D printing the stand-ins, or surrogate parts, in High Temp Resin on the Form 2 stereolithography (SLA) 3D printer. He knew he’d be pushing the boundaries of the material; the final parts would be injected at 270 °C at an injection pressure of 27,000 psi, on the higher end of the published heat deflection temperature (HDT) for High Temp Resin.
“In order to get the small feature size and the shut-offs that we needed, we needed that resolution. It was really the combination of resolution and high temperature resistance that allowed us to use the Form 2 on this,” Allen said. “We have the ability to select from many other fabrication technologies, but having the option to make these parts is really an important piece of our lab.”
The team quickly got to work, printing some parts to test overnight.
“We had no time to redo any CAD on this. I opened it, exported an STL, and threw it at the PreForm software. Once we got that first batch of validation, we just cranked it. We ran 200 parts the first cycle and then we ran another 100 more,” Allen said.
PreForm is Formlabs’ free print preparation software, which can be used to lay out parts on the build platform in batches. Once they ramped up, Allen printed 250 inserts in batches of 10, which each took about four hours, so the team was able to fabricate hundreds of parts over one weekend.
The 3D printed parts worked perfectly as substitutes for the electronic sub-assemblies. The process reduced the lead time for the PCBA inserts from three weeks to three days, and the cost per insert dropped from $100 to $0.80.
“It allowed us to intercept the process further down the line and save a bunch of upfront steps. Three or four upfront steps were just erased by doing it this way. It saved a bunch of time,” Beardsley said.
Because the printed parts were incredibly affordable to produce, the team was able to provide more than the factory had estimated they would need, ensuring they could run shots uninterrupted until they saw satisfactory results.
“The fact that we were able to shut the tool off on 3D printed material, hit it with that high-pressure injection, and not even have it flash, that's a bit unique. Had we not had the Form 2, we would not have been able to pull this off,” Beardsley said.