Ceramic substitutes pressed parts
Ceramic injection molding offers greater geometric latitude than the ‘dry pressing’ of materials with identical characteristics.
The focal point with the ‘dry pressing’ operation is the single-axis and isostatic nature of this process. This involves finely granulated ceramic powder being filled into a pressure mold with a small amount of organic bonding agent. In the two-sided pressing operation, parallel movement of the top and bottom cylinder compresses the granulate. In the one-sided pressing operation, pressure is only applied from above.
Due to the lower proportion of bonding agent, the ‘debinding agents’ needed with injection molding are not required. This makes the baking or curing process somewhat less costly. The substantially lower proportion of bonding agents and the absence of corresponding anti-friction agents do however impose limits on the geometric complexity of components and can also give rise to enormous differences in pressure in the component. If these intrinsic stresses cause distortion during the sintering process, this needs to be adjusted back again by a commensurate amount of mechanical rework (i.e. machining).
Injection molded components may have no need whatsoever for this rework, or less of it may be needed. In overall terms, the additional cost of mechanical rework may ultimately make the pressed component more expensive to manufacture than its injection molded counterpart. Moreover, injection molding is more flexible, giving materials a higher degree of geometric latitude. Pressing remains the process of choice for less complex, two-dimensional geometries.
Ceramic injection moldings versus pressing
- Greater geometric latitude for molds
- Less expensive production in isolated cases
- Identical material characteristics