Multi-material powder bed fusion system design and operation

Purpose Multi-material manufacturing with functional gradients and local composition control (LCC) is an emerging technology with potential to solve an array of problem sets in numerous industries. Multi-material additive manufacturing is rapidly advancing and is poised to fill much of the multi-manufacturing demand. The purpose of this study is to explore techniques for multi-material powder bed fusion (PBF) to expand the accessibility and benefit of multi-material manufacturing. Design/methodology/approach A multi-material selective laser sintering (SLS) prototype, including novel subsystems and processes integrated with traditional PBF methodologies, was developed. Multi-material structures were printed with blends of polyamide-12, thermoplastic elastomer, carbon fibers and hydroxyapatite particulates to characterize these functions. Bi-material manufacturing utilized two internal powder reservoirs, whereas 3+ material parts were enabled by external material exchange during printing. Along with optimizing conventional process parameters, advanced techniques like multi-material anchoring, multi-pass lasing and recoating were developed to facilitate LCC. Findings Multi-material parts were successfully printed. Multi-pass lasing and multi-material anchoring (printing stiff materials at the base of the part) can minimize warping, a major challenge during multi-material printing. Multi-pass recoating minimized cross-contamination and voids between materials. Analyzed material gradients indicate seamless LCC. Originality/value Presented material combinations and printing processes demonstrate a family of materials and process parameters that support printing multifunctional material structures through SLS. These materials and process parameters have not been found in previous publications and can fill current technology gaps.