U-M Develops Software to Help 3-D Printers Make Better Parts Faster

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Mechanical engineering Ph.D. candidate Chuan He and associate professor Chinedum Okwudire demonstrate the laser marking procedure using a Panda 11 LPBF printer. // Courtesy of Evan Dougherty/Michigan Engineering
Mechanical engineering Ph.D. candidate Chuan He and associate professor Chinedum Okwudire demonstrate the laser marking procedure using a Panda 11 LPBF printer. // Courtesy of Evan Dougherty/Michigan Engineering

Engineers at the University of Michigan in Ann Arbor have developed software called SmartScan that may soon allow 3-D printers to more efficiently make more precise intricate metal and plastic parts.

The software reduces harmful heat buildup in laser powder bed fusion printers and demonstrated a 41 percent improvement in heat distribution and a 47 percent reduction in deformations in a recent study.

The development also is likely to speed the manufacturing process in two ways: by reducing the need for printers to slow down to help with cooling and by significantly reducing heat-caused defects that must be corrected after printing.

Laser powder bed fusion is a form of 3-D printing — also called additive manufacturing — used in aerospace, automotive, and biomedical industries to manufacture parts that are too intricate to make with conventional manufacturing. It uses a laser to fuse layers of powdered metal or plastic together. But the laser’s heat can build up in the delicate parts being printed, causing deformation and other defects.

“This problem gets even more serious for parts with really thin features,” says Chinedum Okwudire, associate professor of mechanical engineering at U-M and corresponding author of the paper in the Additive Manufacturing trade journal. “The heat doesn’t have a lot of room to spread, so you need to be smart about how you move the laser around, otherwise your part will deform in really weird ways.”

SmartScan tackles the problem by considering how heat flows within a given part and mapping an optimized scan sequence to limit heat accumulation in any given area. It analyzes the shape of the part and the thermal properties of the material being used, including conductive and convective heat transfer.

Others in the field have experimented with varying printing patterns to reduce heat buildup, for example by jumping from one area to another or alternating between horizontal and vertical scanning directions. But Okwudire says SmartScan is the first solution that uses a thermal model to optimally guide the laser to distribute heat more evenly.

“When you bring science into it, you can do it in a way that is better and works for even the most intricate parts,” Okwudire says.

To determine the effectiveness of this first version of SmartScan, the researchers used a laser to imprint an identical pattern on two stainless steel plates. They used the SmartScan process for the first plate and switched to traditional printing patterns for the second plate. The prints made with SmartScan were consistently less warped and showed more uniform heat distribution during the marking process than the other methods.

Based on the results of the experiment, the team says it is confident that, with further research, they’ll be able to adapt SmartScan to build full 3-D parts. The team members plan to further improve the software by factoring the fusing of metal or plastic powder into their thermal modeling, as well as enabling active updating of a scan sequence during printing based on real-time observed temperature measurements using an infrared camera.

“The results are very promising, and we’ve gotten a lot of positive feedback,” says Okwudire, who has started to demonstrate the software to industry partners. “We went with a simple model because it works, and it works better than the trial-and-error approaches used today. We wanted to focus in a direction that is practical and truly has the chance to make a difference.”

The study was supported by the U-M College of Engineering and Department of Mechanical Engineering. The University of Michigan has filed for patent protection and is seeking partners to bring the technology to market.

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