The MIM process (metal powder injection moulding) represents a comparatively new, powder metallurgical manufacturing route. It essentially consists of the sub-steps of injection moulding, debinding and sintering. A so-called feedstock is used as the starting material, which is often made up of spherical metal powder particles and an organic binder. The composition of the feedstock and the process parameters selected during injection molding determine the density of the produced green part and its microstructure. The binder is subsequently removed and the following sintering process converts the porous green body into a dense component with the appropriate strength. While the injection molding process enables the production of a highly complex and at the same time precise component in a very short process time, the sintering process and the induced shrinkage are often associated with significant distortion. This is additionally intensified by the friction occurring between the green body and the setter plate. As the sintering kinetics are significantly influenced by the sintering temperature and the microstructure of the green body, there are complex interactions between the individual process steps. Consequently, a sound understanding of the process is required in order to produce dimensionally stable components. A simulation-supported process development, on the other hand, can enable a significant reduction in development times and an improvement in component quality.
The objective of the project is the development of a simulation tool for the precise prediction of the shrinkage and the distortion that occur during sintering of MIM-components. The influence of the feedstock characteristics as well as the sintering temperature and the temperature dependent friction will be taken into account. The numerical simulation will be then used to mitigate the distortion by optimizing the shape of the green part.
- Determination of material parameters to describe the sintering process
- Determination of the friction coefficient as a function of temperature and feedstock composition
- Derivation of a a constitutive law to describe the sintering kinetics dependent on temperature, density- and feedstock composition
- Validation of the simulation by experimental investigations
- Development of a numerical simulation- and optimization-tool
- Numerical optimization of the geometry of green parts
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IGF-Grant Number: KK5145701 SH0