Powder Injection Molding (PIM) technologies allow to mold complex shaped parts starting from a compound rich in metal (MIM processes) or ceramic (CIM processes). These technologies stand out as an excellent alternative processing method since they allow shaping metal and ceramic parts like plastic ones and, thanks to subsequent heat treatments, lead to true metallic or ceramic parts.
The market is fast growing with an annual growth rate of two digits, much higher than the plastics AGR.
The Powder Injection molding involves 4 to 5 steps:
- Mixing finely powdered metal particles with a low quantity of wax or polymer binder to obtain a compound with a rheology suitable for injection molding.
- Injection of the compound under high pressure in slightly modified injection machines to obtain the part.
- Debinding of the moldings obtained by thermal decomposition of the binder in an oven to obtain the moldings.
- Sintering at high temperature (1300°C during several hours for example) fuses the metal particles together, which results in a high-density and strong part.
- If needed in applications involving harsh environments, final step includes finishing: machining, polishing, plating, hardening, etc.
After injection, debinding and sintering, the MIM products have up to 98% of the density of the metal and can have better mechanical performances than cast grades of the same composition. Tolerances without secondary processes are in the order of some per-thousand.
The PIM parts are generally of a small to medium size, high complex shape, and moderate to close dimensional tolerances. The other properties include those of the selected metal or ceramic.
Application sectors include medical, dental, electronic, firearms, aerospace, jewellery, watch making industry, binocular frames, orthodontic brackets, and automotive.
The global PIM market is estimated at $1.6 billion in 2010 with an annual growth rate approximately in the order of 14%.