The ceramic injection molding process is shown below in graphic form:
From powder to feedstock (selection / preparation / compounding)
The ceramic powder is selected according to the functional requirements of the finished component. By mixing different ceramic powders, it is also possible to change the material-specific property profile and adjust it to the application. The ceramic powder or powder mixture is then mixed with wax or thermoplastic-based components (binder systems), homogenized and granulated. This feedstock can be plasticized by means of a binder system and can therefore be used in an injection molding machine. The necessary melt temperature is determined by the binder system.
Injection molding
The plasticized feedstock is injected under pressure into the injection mold. In the ceramic injection mold, the material returns to its solid state by cooling and is removed as a finished part after opening the ceramic injection mold. The cavity of the ceramic injection molding tool determines the shape and surface structure of the finished part. By means of appropriate tool technology, 3-dimensional geometries can be mapped in one process step.
Debinding
The aim of the debinding process is a complete removal of the organic binder without influencing the component geometry and the chemical purity of the material. Depending on the feedstock, different debinding strategies are required.
- thermal
- catalytic table
- solvents
Sintering
The debinded parts are sintered at the material-specific temperature (e.g.: Al2O3 - approx. 1,650°C; ZrO2 approx. 1,400°C). During this process, the ceramic grains grow together, close the pores created by debinding and form a closed, dense structure. The shrinkage that occurs (between 16 -28% depending on the material) is taken into account in the tool design in advance. An adapted temperature control and suitable sintering supports or sintering aids determine a high dimensional stability and component quality.
Mechanical processing (option)
Ideally the components are used "as fired". However, for functional (e.g. polished surface, extremely sharp edges, etc.) or dimensional reasons, mechanical reworking may be necessary. Basically, all mechanical processing methods such as surface or cylindrical grinding, vibratory grinding, drilling, lapping, honing... are possible.
