CIM – Ceramic Injection Moulding

Vibrom spol. s r.o. specialises in the processing of high-purity oxide ceramics, in particular:

• Aluminium oxide (_Al₂O₃): characterised by its hardness and chemical resistance.
• Zirconia (_ZrO₂): characterised by high fracture toughness and abrasion resistance.

A key aspect of our expertise is the in-house preparation of feedstock. The process involves the precise dosing of submicron ceramic powders and a multi-component polymer binder. Homogenisation takes place under defined rheological conditions, followed by granulation. Our proprietary feedstock formulation enables us to precisely control viscosity and subsequent shrinkage during firing.

Due to the high abrasiveness of ceramic fillers, the feeding screws of injection moulding machines are fitted with highly resistant coatings (e.g. tungsten carbide-based), which prevent contamination of the melt by abraded metal particles – a critical factor in maintaining the dielectric and mechanical properties of the resulting ceramics.

The mould geometry is designed taking into account the material’s shrinkage coefficient, which ranges from 15 to 25 per cent depending on the binder content.

Once removed from the mould, the product is in the so-called ‘green part’ stage (green semi-finished product). This is followed by a two-stage transformation process:

1. Debinding (removal of the binder): A critical phase during which the organic component is gradually extracted. The process is controlled to ensure that the structural integrity of the part is not compromised (i.e. no cracks or deformations occur). The result is the so-called ‘brown part’.
2. Sintering: Sintering takes place at temperatures close to the melting point of the material in question (1400–1600 °C). This involves solid-state diffusion, the elimination of porosity and the formation of crystalline bonds between the grains. During this stage, the product achieves its final density, hardness and mechanical strength.

Despite the high precision of the CIM process, we carry out additional operations to achieve extremely tight tolerances:

• Tumbling and polishing: Adjustment of surface roughness (Ra) for functional surfaces.
• Overmoulding: We offer technology for moulding ceramic inserts into polymer matrices, thereby creating highly durable composite assemblies.