Development of paste extrusion-based metal additive manufacturing process

Abstract

Purpose This study aims to explore a technique of metal additive manufacturing (MAM) for producing parts in aluminium. The proposed technique mimics the process of metal injection moulding but with the tools meant for fused freeform fabrication machines. Design/methodology/approach The work focusses on the preparation of novel feedstock by mixing the aluminium powder with binders made from different compositions of high-density polyethylene, paraffin wax, petroleum jelly and stearic acid. Further, a novel experimental setup with a paste extruder was designed to print the test samples. A sintering cycle was developed in-house along with a thermal debinding procedure. An experimental campaign was also carried with the proposed technique to establish a proof-of-concept. Produced samples were tested for part density, hardness, compressive strength and tensile strength. Findings The results indicate geometrical accuracy was an issue owing to the presence of petroleum jelly in the binder-powder mixture. Therefore, machining as a post-processing operation seems to be unavoidable. The study also elucidates that the printed specimen may require further heat treatment to replace wrought alloys. However, the sintered parts show hardness and compressive strength similar to that of wrought aluminium alloy. Originality/value The novelty of the work is to develop the cost effective and scalable powder extrusion-based MAM process for printing the aluminium parts.