Additive manufacturing (AM) or three-dimensional (3D) printing allows manufacturing of parts of complex shapes using carbon fiber reinforced polymer (CFRP) composites. However, in many cases, the parts fabricated by 3D printing suffer from poor surface quality and dimensional accuracy, requiring extensive post-processing. This research aims at improving the dimensional accuracy and surface finish of 3D printed CFRP composites by analyzing the effectiveness of three sustainable machining practices: dry, minimum quantity lubrication (MQL), and cryogenic machining, as post-processing techniques for 3D printed CFRP composites. This study specifically investigates effects of printing and machining parameters and cooling/lubricating conditions on the machining performance, i.e., burr formation, surface finish, cutting forces, and tool wear during edge and slot milling of 3D printed thermoplastic CFRP composites. Among three sustainable machining processes, cryogenic machining significantly reduced burr formation and tool wear, and improved surface finish irrespective of the fiber orientation and machining conditions. The application of MQL at the tool-workpiece interface was found to be effective in reducing tool wear, surface roughness, and burr formation to some extent compared to dry machining. However, MQL process was not able to completely eliminate burr formation for most of the machining conditions. Cryogenic machining caused the highest cutting forces due to the increased surface and sub-surface hardness of the workpiece caused by application of liquid nitrogen; however, no adverse effect of increased cutting forces was observed. This study finds that cryogenic machining is able to completely eliminate or reduce burrs by 90% and bring down the surface roughness (Rq) from >10 μm to about 1 μm, thus making it a suitable post-process technique for 3D printed CFRP composites.

增材制造 (AM) 或三维 (3D) 打印允许使用碳纤维增强聚合物 (CFRP) 复合材料制造复杂形状的零件。然而，在许多情况下，3D 打印制造的零件表面质量和尺寸精度较差，需要大量的后处理。本研究旨在通过分析三种可持续加工实践的有效性来提高 3D 打印 CFRP 复合材料的尺寸精度和表面光洁度：干法、微量润滑 (MQL) 和低温加工，作为 3D 打印 CFRP 复合材料的后处理技术。本研究专门研究了打印和加工参数以及冷却/润滑条件对加工性能的影响，即毛刺形成、表面光洁度、切削力、3D 打印热塑性 CFRP 复合材料的边缘和槽铣削过程中的刀具磨损。在三种可持续加工工艺中，无论纤维取向和加工条件如何，低温加工都显着减少了毛刺形成和刀具磨损，并改善了表面光洁度。研究发现，与干式加工相比，MQL 在刀具-工件界面上的应用在一定程度上能有效减少刀具磨损、表面粗糙度和毛刺形成。然而，MQL 工艺无法完全消除大多数加工条件下的毛刺形成。由于使用液氮会增加工件的表面和亚表面硬度，因此低温加工会产生最高的切削力；然而，没有观察到增加切削力的不利影响。