AlFaify Abdullah Yahia, Saleh Mustafa, Anwar Saqib, Al-Ahmari Abdulrahman M, AbdElgawad Abd Elaty E
Industrial Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
Polymers (Basel). 2025 Aug 31;17(17):2372. doi: 10.3390/polym17172372.
Material extrusion (MEX) is an additive manufacturing process used for 3D printing thermoplastic-based polymers, including single polymers, blends, and reinforced polymer composites (RPCs). RPCs are highly valued in various industries for their exceptional properties. The surface finish of RPC MEX-printed parts is high due to the process-related layering nature and the materials' properties. This study explores RPC development for MEX printing and the potential of dry milling post-processing to enhance the MEX-printed part's surface quality. RPC MEX filaments were developed by incorporating graphene nanoplatelets (GNPs) and/or recycled-carbon fibers (rCFs) into a polylactic acid (PLA) matrix. The filaments, including pure PLA and various GNPs-PLA composites, rCF-PLA, and rCF-GNPs-PLA, were developed through ball mill mixing and melt extrusion. Tensile tests were performed to assess the mechanical properties of the developed materials. Dry milling post-processing was carried out to assess the machinability, with the aim of enhancing the MEX-printed part's surface quality. The results revealed that adding GNPs into PLA showed no considerable enhancements in the tensile properties of the fabricated RPCs, which is contrary to several existing studies. Dry milling showed an enhanced surface quality of MEX-printed parts in terms of surface roughness (Sa and Sz) and the absence of defects such as delamination and layer lines. Adding GNPs into PLA facilitated the dry machining of PLA, resulting in reduced surface asperities compared to pure PLA. Also, there was no observation of pulled-out, realigned, or naked rCFs, which indicates good machinability. Adding GNPs also suppressed the formation of voids around the rCFs during the dry milling. This study provides insights into machining 3D-printed polymer composites to enhance their surface quality.
材料挤出（MEX）是一种增材制造工艺，用于3D打印热塑性聚合物，包括单一聚合物、共混物和增强聚合物复合材料（RPC）。RPC因其卓越的性能在各个行业中备受重视。由于与工艺相关的分层特性和材料性能，RPC MEX打印部件的表面光洁度较高。本研究探索用于MEX打印的RPC开发以及干铣削后处理提高MEX打印部件表面质量的潜力。通过将石墨烯纳米片（GNP）和/或回收碳纤维（rCF）加入聚乳酸（PLA）基体中来开发RPC MEX长丝。通过球磨混合和熔融挤出制备了包括纯PLA以及各种GNP-PLA复合材料、rCF-PLA和rCF-GNP-PLA在内的长丝。进行拉伸试验以评估所开发材料的力学性能。进行干铣削后处理以评估可加工性，目的是提高MEX打印部件的表面质量。结果表明，在PLA中添加GNP对所制备的RPC的拉伸性能没有显著增强，这与一些现有研究相反。干铣削在表面粗糙度（Sa和Sz）以及不存在分层和层线等缺陷方面提高了MEX打印部件的表面质量。在PLA中添加GNP有助于PLA的干式加工，与纯PLA相比，表面粗糙度降低。此外，未观察到rCF被拉出、重新排列或裸露，这表明可加工性良好。添加GNP还抑制了干铣削过程中rCF周围孔隙的形成。本研究为加工3D打印聚合物复合材料以提高其表面质量提供了见解。
