In additive manufacturing, or 3D printing, the product is not formed from one piece, but is applied layer by layer. This enables precise and individual production with precisely defined product properties. The technology is constantly being developed: Initially, it was mainly plastics, but for some time now metals or ceramic-based materials have also been processed.
The Fraunhofer IKTS is now taking a big step forward. The researchers have developed a system that enables the additive production of multi-material components based on thermoplastic binder systems. The system works on the principle of Multi Material Jetting (MMJ). In this process, different materials with their different characteristics are combined to form a product. Currently, scientists can process up to four materials simultaneously. The areas of application are diverse and are located wherever companies want to produce highly integrated multifunctional components with individually defined properties.
The production is a continuous process. First, the powdered ceramic or metallic starting materials are homogeneously distributed in a thermoplastic binder substance. The masses produced in this way are filled into micro-dosing systems (MDS), whereupon the actual production process starts. During this process, the masses are melted at around 100 degrees Celsius, making them very finely metered. Precise positioning of the droplets is achieved using specially developed software. The dosing systems are computer-controlled and deposit high-precision drop by drop in the right place, causing the component to build up pointwise – up to 60 mm and 1000 drops per second.
The system works with a drop size between 300 and 1000 μm, resulting in a height of the applied layers between 100 and 200 μm. The maximum size that can currently be produced is 20 × 20 × 18 centimeters. “The decisive factor is the individual dosing of the metal or ceramic masses. This dosage ensures that the additively manufactured end product receives the desired properties and functions such as strength, thermal and electrical conductivity during the final sintering process in the furnace,” says IKTS scientist Uwe Scheithauer.
The IKTS system can also be used to produce highly complex components – such as the igniter in a satellite engine made of ceramic. Extremely high temperatures prevail in the combustion chamber of such an engine. The heat-resistant ceramic is an ideal material for this. MMJ can be used to produce an igniter for the engine that is directly integrated and also combines electrically conductive and electrically insulating areas in a single, extremely robust component. This requires three dosing systems: one for a supporting support material that decomposes during heat treatment in the furnace, a second for the electrically conductive and a third for the electrically insulating component.
Due to the high precision and flexibility of the system, it is not only suitable for the production of multifunctional components. “For example, we could also produce the blanks for workpieces made of hard metal. Since the dosing systems work extremely precisely, the blanks are already very close to the final contour and, unlike with conventional processes, hardly need to be laboriously reground. This is a great advantage with carbide,” says Scheithauer.
According to the IKTS scientists, the project shows that the technology is practical and scalable. The next step will now be validation for industrial use. In addition to hardware, the IKTS also offers industrial customers material and software development for process monitoring and automation.
Interested parties will have the opportunity to get to know the technology at the digital AM Ceramics meets CERAMITEC Conference on 16 and 17 September 2020 (www.am-ceramics.dkg.de ).
More information: https://www.ikts.fraunhofer.de/en.html