Multi Jet Fusion (MJF) is an emerging additive manufacturing (AM) technique that enables the production of prototypes and functional parts starting from a thermoplastic-based powder, mainly polyamide 12 (PA12). Layer upon layer, the polymeric particles are selectively impregnated with two different inks and then fused and consolidated by an infrared (IR) lamp. Much faster than other AM techniques for polymers, MJF has shown exciting potentialities. However, little is known about the consolidation mechanisms acting in MJF and about the effect on the properties of the finished parts of the quality of the materials, powder and inks, and of the printing conditions. The present contribution investigates these issues. The study also compares virgin PA12 powder with pure PA12, recycled PA12 for MJF and PA12 for in selective laser sintering (SLS). The powders showed slight differences. The two inks have the same composition, except for the presence of graphitic carbon. Tensile tests showed that the printed parts are isotropic. However, the deformation at break is affected by building direction of the sample. Occasionally, poor inter-layer adhesion is observed and the tensile strength and the deformation at break collapse. Printed tensile specimens are found to be representative of the material behaviour of a printed component, apart from the deformation at break which is systematically overestimated.

Multi Jet Fusion（MJF）是一种新兴的增材制造（AM）技术，能够从热塑性基粉末（主要是聚酰胺12（PA12））开始生产原型和功能部件。一层又一层地，用两种不同的油墨选择性地浸渍聚合物颗粒，然后通过红外线（IR）灯熔化和固结。MJF比其他用于聚合物的增材制造技术快得多，已显示出令人兴奋的潜力。但是，对于在MJF中起作用的固结机理以及对制成品的性能，材料质量，粉末和油墨质量以及印刷条件的影响知之甚少。本文稿调查了这些问题。该研究还比较了纯PA12粉末与纯PA12粉末，用于MJF的回收PA12粉末和用于选择性激光烧结（SLS）的PA12粉末的比较。粉末显示出细微差异。除存在石墨碳外，两种油墨的成分相同。拉伸试验表明，印刷零件是各向同性的。但是，断裂变形受样品的构建方向影响。有时会观察到较差的层间粘合力，并且拉伸强度和断裂变形会崩溃。除了系统地高估了断裂变形之外，发现印刷的拉伸试样还代表了印刷部件的材料性能。观察到差的层间粘合力，并且拉伸强度和断裂变形破坏。除了系统地高估了断裂变形之外，发现印刷的拉伸试样还代表了印刷部件的材料性能。观察到差的层间粘合力，并且拉伸强度和断裂变形破坏。除了系统地高估了断裂变形之外，发现印刷的拉伸试样还代表了印刷部件的材料性能。