Daniel Porter

Additive manufacturing (AM) can create orthopedic devices with integrated porosity that enables bone fixation post‐implantation. While porosity is key in promoting bone ingrowth and long‐term fixation, the device must provide adequate mechanical strength and functionality. Since AM process parameters dictate the final mechanical performance of printed parts, identifying key process parameter levels that preserve or improve such behavior in load‐bearing devices with integrated porosity is essential. Using a Taguchi design of experiments, gyroid‐structured polyether‐ether‐ketone (PEEK) and polyether‐ketone‐ketone (PEKK) specimens were fabricated via fused filament fabrication (FFF) AM to examine the impact of nozzle temperature ( T _N ), chamber temperature ( T _Ch ), and layer height (LH) on their compressive mechanical behavior. In addition to compression testing, the printed specimens were analyzed using optical microscopy, scanning electron microscopy, and micro‐computed tomography. Elevated processing conditions, specifically high T _Ch combined with thick LH, can enhance heat retention, slow crystallization, increase strut thickness, and improve bonding at strut junctions, enabling porous PEEK and PEKK to withstand higher compressive loads. The elastic moduli of all the porous specimens were more sensitive to variations in processing conditions than their yield strength. Notably, the more amorphous PEKK specimens achieved over 87%–88% of PEEK's calculated elastic modulus in this study and 87%–90% of the yield strength without undergoing annealing. These results are promising, considering that, like PEEK, the elastic modulus of the porous PEKK fell within the range of trabecular bone, while its yield strength surpassed that of trabecular bone.

Multi-laser Additive Manufacturing systems hold great potential to increase productivity. However, adding multiple energy sources to a powder bed fusion system requires careful selection of a laser scan and inert gas flow strategy to optimize component performance. In this work, we explore four different laser scan and argon flow strategies on the quasi-static compressive mechanical response of Body Centered Cubic lattices. Three strategies employ a swim lane method where laser pathing tends to progress parallel to argon flow. Method one only uses a single laser while method two uses four, both with the laser path working against the argon flow. The third method uses four lasers, each operating in their own lane like the second method, but the laser pathing progresses with the argon flow. The fourth method has all four lasers operating in quadrants and the laser pathing trends against the argon flow. The single-laser strategy generally had the lowest mechanical responses compared to the other three strategies. A quadrant strategy generally had the highest quasi-static mechanical responses and was at least 25% greater in stiffness, yield force, ultimate force, and energy absorption when compared to the single laser strategy. However, the four-laser swim strategy where the laser pathing tends against the argon flow was found to be statistically similar to the quadrant strategy. It is hypothesized that spatter introduced onto the powder layer from the melt pool and particle entrainment may be worse for laser pathing which trends with the argon flow direction. Additionally, the additional energy added to the build volume helps to mitigate inter-layer cool time which reduces temperature gradients. This shows that multi-laser AM systems have an impact on part performance and potentially shows lattices built with multi-laser AM systems may have certain advantages over single-laser AM systems.