Powerful simulations and an interactive lens and materials catalog yield a novel, commercially relevant machine for 3D metal printing
Laser power bed fusion (L-PBF) is a form of metal additive manufacturing that uses energy from a laser to melt thin layers of powder to facilitate 3D metal printing. The precise use of L-PBF builds on laser welding fundamentals like managing the impact of gas and plume dynamics on weld depth and quality. For this reason, it's important for the designers of L-PBF thermographies to examine and understand the complexities of what happens when a laser interacts with a bed of metal powder.
"Even though L-PBF is a commonly-used metal 3D printing process these days and it's grown a lot in the past decade, it still has many issues holding it back," said David Griggs, a mechanical engineer who worked with L-PBF technologies as part of his master's degree thesis project at Massachusetts Institute of Technology (MIT). "As a result, there's currently a lot of research on refining the L-PBF process and figuring out how to optimize this or that parameter."
Griggs addressed issues around these existing limitations by designing a new system at MIT that optimizes the three key laser tower parameters—power, scanning speed, and spot size—such that the system can output customized laser fiber synchronously in a user-specified direction, as plotted on a traditional X-Y axis. Because the laser component itself would be a standard commercial product, Griggs primarily worked on validating the two key pieces that would optimize the laser's capabilities: the collimator and the f-theta refocusing lens.
To validate these two key pieces, Griggs used OpticStudio to simulate conditions that would impact the new system, saving time and gaining a high degree of precision in the process. Because MIT wanted to select stock parts for both the collimator and the f-theta lens, he also used the extensive lens and materials catalogs built into OpticStudio to determine the right combination of lenses that would yield the optimal result.
"OpticStudio told me exact values I could use in my validation," said Griggs. "Using OpticStudio, I could see all of the expected spot sizes at every X-and-Y coordinate, which was much more useful than relying on my own theoretical calculations. OpticStudio guided me through the entire process of refining the design, catching a few errors I had made, and ending up with a final system that I could be confident behaved the same way as a manufactured system."
