Sintering process - Powder injection moulding (PIM)

The powder injection molding (PIM) process was first adopted by the ceramics industry in the 1970s. The process then spread more widely to the field of metal powders. Although the PIM industry has experienced strong growth since its inception, the number of parts produced by this process remains on the order of a few percent compared with the total number of parts produced by conventional powder metallurgy and technical ceramics techniques.

The PIM process combines the advantages of plastic injection molding and powder metallurgy to produce complex parts in small, medium or large production runs, in materials that can be very difficult to machine. What's more, this process is particularly well suited to small parts. It is therefore virtually indispensable in the field of microtechnology.

Parts with highly complex shapes can be produced directly, or with only minor machining operations. Since the surface finish and precision of the resulting parts are excellent, finishing and polishing operations are greatly reduced, or even eliminated. Significant reductions in production costs are thus possible compared with sintering pressed parts, for example.

In this dossier, after comparing PIM technology with conventional processes, we describe the basic principles and typical problems encountered during the various stages (feedstock constituents and composition, molding and debinding conditions). We will then focus on sintering in the specific case of this process:

• theory of the sintering phenomenon ;

• details of equipment used in the industrial sector;

• difficulties commonly encountered when sintering various materials (metallic and ceramic);

• new techniques currently under development.