Large format additive manufacturing (LFAM) necessitates the use of short fiber thermoplastic composites, such as carbon fiber filled acrylonitrile butadiene styrene, to enable printing. Currently, when LFAM parts are machined into their final shape, the machining scrap ( small flake like particles and offcuts) is landfilled. Previous studies have demonstrated the viability of recycling end-of-life LFAM parts by shredding and optionally re-compounding the material back into pellets. However, there is little understanding of the value and performance of recycled material made from LFAM machining scrap, which if pursued could motivate more broad recycling of this waste stream. In this study, recycled in-process machining scrap is explored as an LFAM feedstock source. Herein, it is found that the primary degradation mechanism of the recycled material is significant fiber length attrition during surface machining. While this fiber attrition negatively impacts the mechanical performance of the material in the print direction, it seems that the changes in processing behaviors and print quality, namely the surface roughness of the printed structure associated with shorter fiber lengths, is beneficial to interlayer adhesion. The tensile strength and elastic modulus of the recycled material, in the print direction, decreased 11% and 31% respectively compared to the pristine material. However, in the layer-wise direction it was found that the recycled material exhibited no significant change in elastic modulus and a significant 21% increase in tensile strength – a surprising result. This work indicates that machining waste could be a viable material stream for recycled LFAM feedstock materials.

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CF-ABS 加工废料回收用于大幅面增材制造

大幅面增材制造 (LFAM) 需要使用短纤维热塑性复合材料（例如碳纤维填充的丙烯腈丁二烯苯乙烯）来实现打印。目前，当 LFAM 零件被加工成最终形状时，加工废料（小片状颗粒和边角料）会被填埋。之前的研究已经证明了通过粉碎并选择性地将材料重新复合成颗粒来回收报废 LFAM 零件的可行性。然而，人们对由 LFAM 加工废料制成的回收材料的价值和性能知之甚少，如果采取这种做法，可能会促进更广泛地回收这种废物流。在本研究中，探索了回收的加工过程中的废料作为 LFAM 原料来源。在此，发现回收材料的主要降解机制是表面加工期间显着的纤维长度磨损。虽然这种纤维磨损会对材料在打印方向上的机械性能产生负面影响，但加工行为和打印质量的变化（即与较短纤维长度相关的打印结构的表面粗糙度）似乎有利于层间粘合。与原始材料相比，回收材料在打印方向上的拉伸强度和弹性模量分别下降了11%和31%。然而，在层状方向上，我们发现回收材料的弹性模量没有显着变化，拉伸强度却显着增加了 21%，这是一个令人惊讶的结果。这项工作表明，机械加工废料可能是回收 LFAM 原料的可行材料流。