New processes for additive manufacturing of ceramics

At Fraunhofer-Center HTL, new methods for additive manufacturing are developed, and  existing methods are improved. The objective of these developments is to broaden the state of the art and to qualify the processes for industrial component manufacture. Based on the market and customer requirements, requirements for new additive manufacturing processes are derived. From this, concepts for implementation are developed and coordinated with the customer. Subsequently, prototype manufacturing systems can be built according to the customer’s requirements.

The requirements for new additive manufacturing methods include, among other things, high green densities, in-situ control of the printing process, scalability of the processes and the option of 3D multi-material printing. At the same time, the processes must be economically viable.

One current development focuses on a slurry-based 3D multi-material print process (Free Flow Structuring). The process specifically combines existing additive manufacturing technologies to produce high-quality components made from several materials in a single print job. Regarding subsequent industrial series production, the process is designed so that components with large dimensions can also be produced. Parallel to the development of the process, the corresponding plant prototype is built.

A further development deals with additive manufacturing based on electrophoretic microfluidics (see Vogt, L.; Schäfer, M.; Kurth, D.; Raether, F.: Usability of electrophoretic deposition for additive manufacturing of ceramics). In contrary to other methods of electrophoretic deposition, the particles are only made available where they are required for the construction of the component. Using this process, high green densities and very homogeneous microstructures can be achieved, which is a fundamental prerequisite for high quality of the printed components. At the same time, the process offers the option of 3D multi-material printing at high resolution. By parallelizing many arrays, the productivity of the process can be significantly increased.

Quality management plays an important role, in particular in 3D multi-material printing, as the processes are more susceptible to defects. For example, the interfaces between two material types must be strictly controlled to avoid delamination. A particular challenge involves the thermal processing of the components, as the different materials normally have varying requirements for drying, debinding and sintering. At this point, the use of FE simulations in combination with in-situ measurement methods represents an effective approach for the targeted optimization of the thermal processes.