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Feasibility study on piston-based feedstock fabrication with Ti-6Al-4V metal injection molding feedstock
Additive Manufacturing ( IF 11.0 ) Pub Date : 2020-05-13 , DOI: 10.1016/j.addma.2020.101207
Lennart Waalkes , Jan Längerich , Felix Holbe , Claus Emmelmann

The use of feedstocks from metal injection molding (MIM) for the additive manufacturing (AM) of green parts, which are then debound and sintered in a process called shaping, debinding, and sintering (SDS), is promising in terms of production costs of metallic parts. However, in order to use the cost-efficient AM technique fused filament fabrication (FFF) for SDS, powder-binder mixtures known for MIM feedstocks must be adapted to filament requirements resulting in adjustments to debinding and sintering. In contrast to FFF, screw-based material extrusion is capable of processing already available MIM feedstocks, but machine costs are high due to complex print heads. In this work, a new process called piston-based feedstock fabrication (PFF) is developed for processing already available MIM feedstocks at comparable costs to FFF. First, the state of the art is reviewed highlighting the potential of piston-based material extrusion for its usage in SDS. Based on the review, an extruder module is developed which is integrated into a kinematic system. Experimental studies are performed to validate the developed PFF printer. As material, a Ti-6Al-4V MIM feedstock is used. Thresholds for piston speed (0.175 mm/min), extrusion temperature (80 °C), and nozzle diameter (0.4 mm) are determined to ensure a viscosity that allows to control the extrusion process via steps per mm. With these thresholds it is found that a constant extrusion process can be established in a filling range of the cylinder up to 155 mm. Finally, the performance of the PFF system is evaluated in terms of nozzle geometry, print speed, and reproducibility showing that reproducible green part properties are achieved at a maximum speed of 8.18 mm/s while using a tapered FFF nozzle.



中文翻译:

Ti-6Al-4V金属注射成型原料制造活塞基原料的可行性研究

使用金属注射成型(MIM)的原料进行绿色零件的增材制造(AM),然后将其通过成型,脱脂和烧结(SDS)的过程进行去粘和烧结,就生产成本而言,这是有希望的金属零件。但是,为了将经济高效的AM技术用于SDS的熔融长丝制造(FFF),必须将已知用于MIM原料的粉末粘合剂混合物与长丝要求相适应,从而对脱脂和烧结进行调整。与FFF相比,基于螺杆的材料挤出能够处理已有的MIM原料,但是由于打印头复杂,因此机器成本很高。在这项工作中,开发了一种称为基于活塞的原料制造(PFF)的新工艺,以与FFF相当的成本加工已经可用的MIM原料。第一,对现有技术进行了回顾,重点介绍了基于活塞的材料挤出在SDS中的应用潜力。在此基础上,开发了一个挤出机模块,该模块已集成到运动系统中。进行实验研究以验证开发的PFF打印机。作为材料,使用Ti-6Al-4V MIM原料。确定活塞速度(0.175 mm / min),挤压温度(80°C)和喷嘴直径(0.4 mm)的阈值,以确保允许通过每毫米步长控制挤压过程的粘度。利用这些阈值,发现可以在圆筒的填充范围达155 mm的范围内建立恒定的挤压过程。最后,根据喷嘴的几何形状,打印速度,

更新日期:2020-05-13
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