The Injection Process in Ceramic Injection Molding (CIM)
The injection process in Ceramic Injection Molding is a critical step where the “green part” is formed. It shares similarities with plastic injection molding but involves a unique feedstock and requires extremely precise control to avoid defects that can manifest in later stages of debinding and sintering.
The feedstock used is a homogeneous mixture of fine ceramic powders and a multi-component polymer binder system (typically waxes, plastics, and lubricants).
Injection Process in Ceramic Injection Molding (CIM):
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Feeding: Granulated ceramic feedstock (ceramic powder + polymer binder) is loaded into the machine’s heated barrel.
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Injection: The mixture is melted into a viscous fluid. A screw then injects it under high pressure into a mold cavity.
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Holding: Critical Step. Pressure is maintained to pack the cavity fully, compensating for shrinkage and preventing defects.
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Cooling: The mold cools, solidifying the binder and forming a fragile “green part.”
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Ejection: The mold opens and the green part is carefully ejected.
Key Points:
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Requires very high pressure and precise control of temperature and speed.
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Essential to avoid binder separation (which ruins the part).
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The abrasive ceramic powder causes high wear on the machine and mold.
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The resulting “green part” is fragile and must be handled carefully before the next debinding and sintering stages.