Wei Xueying, Li Xujun, Bähr Rüdiger
Institute of Manufacturing Technology and Quality Management, Otto-von-Guericke-University Magdeburg, Magdeburg, 39106, Germany.
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, 710049, Xi'an, China.
Heliyon. 2024 Apr 2;10(7):e28899. doi: 10.1016/j.heliyon.2024.e28899. eCollection 2024 Apr 15.
The thermal debinding-sintering process plays an essential role in the context of material extrusion-based additive manufacturing (AM) for producing parts using metal injection molding (MIM). During thermal debinding, metal parts often experience material distortion and porosity, which negatively impacts their mechanical properties. Slowing down the debinding speed is a common approach to mitigate material distortion and porosity. However, this leads to a significant increase in the debinding time. In this study, we carried out debinding-sintering experiments to optimize the distortion and porosity in metal parts. These metal parts were manufactured utilizing bronze/polylactide (PLA) blend filaments and placed in crucibles of different sizes (small, medium, and large), with different heating rates and holding times. The results revealed that the small crucible yielded higher porosity levels in the metal parts, which could be reduced from 23% to 12% by extending both the heating and holding times. In contrast, the medium crucible managed to reduce porosity to approximately 15% without requiring an extension of the processing time. The large crucible, on the other hand, couldn't achieve further porosity reduction due to challenges in reaching the desired temperature. To gain a deeper insight into temperature distribution during the debinding process, we performed numerical simulations using the computational fluid dynamics (CFD) technique and obtained temperature profiles within the kiln using the three crucibles. Ultimately, we carried out standard mechanical tests on the resulting metal parts and evaluated the thermal debinding procedure under various conditions. The approach we employed, combining experiments and numerical simulations, demonstrated significant promise for enhancing the quality of metal parts in the thermal debinding-sintering process.
在基于材料挤出的增材制造（AM）中，热脱脂 - 烧结工艺在使用金属注射成型（MIM）生产零件的过程中起着至关重要的作用。在热脱脂过程中，金属零件经常会出现材料变形和孔隙率问题，这会对其机械性能产生负面影响。降低脱脂速度是减轻材料变形和孔隙率的常用方法。然而，这会导致脱脂时间大幅增加。在本研究中，我们进行了脱脂 - 烧结实验，以优化金属零件的变形和孔隙率。这些金属零件是利用青铜/聚乳酸（PLA）共混长丝制造的，并放置在不同尺寸（小、中、大）的坩埚中，采用不同的加热速率和保温时间。结果表明，小坩埚会使金属零件的孔隙率更高，通过延长加热和保温时间，孔隙率可从23%降至12%。相比之下，中坩埚能够在不延长加工时间的情况下将孔隙率降低至约15%。另一方面，由于难以达到所需温度，大坩埚无法进一步降低孔隙率。为了更深入地了解脱脂过程中的温度分布，我们使用计算流体动力学（CFD）技术进行了数值模拟，并获得了使用三个坩埚时窑内的温度分布曲线。最终，我们对所得金属零件进行了标准力学测试，并评估了各种条件下的热脱脂过程。我们采用的结合实验和数值模拟的方法，在提高热脱脂 - 烧结过程中金属零件质量方面显示出巨大的潜力。
