Polymer Welding of Injection Molded Ceramics and Metals

Abstract

Ceramic or metal-filled plastics are being increasingly used for the production of sintered parts, the function of the plastic being to ensure that the compounds can be processed on the standard types of injection moulding machine in use. Since there are limits to the geometrical complexity of parts that can be produced by injection moulding, it is wise to make these parts up from simple geometries at the “green part” stage. Conventional series welding processes for plastics can suitably be used to this end. This makes it possible to use the plastic, which acts as a processing aid (binder) not only for the injection moulding process but also for joining the individual components, before the joined parts to be debound and sintered. Another positive effect is the possibility of producing material composites (e.g. mould steel/construction steel). An aluminium oxide and a special steel feedstock were used as test materials. In the case of AI₂O₃, a binder component based on polyolefin was selected, and a polyacetal binder was used for the special steel. These materials were used to injection mould AWS (American Welding Society) specimens, which were then joined by heated tool, radiant-heater and vibration welding.