Additive manufacturing of complex structures with a high level of detail
German Aerospace Center
Powder bed-based additive manufacturing
The high-speed sintering process is one of the powder bed-based additive manufacturing processes for polymers. The process principle enables fast, tool-free generation of complex structures from prototypes to small series parts. The system used at the DLR Institute of Vehicle Concepts is the Voxeljet VX200 HSS. Due to the open machine concept, it is very well suited for research along the entire process chain.
The process principle
The technology of High-Speed Sintering (HSS) is based on introducing black ink and thermal energy into white powder to generate components. It processes only thermoplastics, which are sintered with the aid of an infrared lamp.
First, a thin, rectangular layer of powder is applied to a building platform. A print head then injects black ink locally at the points within this layer where a component is to be generated later. In the next step, an infrared lamp is used to apply heat to the entire powder layer, causing the black areas to absorb it more strongly than the white areas. This causes the powder to exceed the melting temperature only at the desired black areas, where it melts. The build platform now lowers by the corresponding layer height and a new thin layer of powder is applied again. This process is repeated layer by layer until the desired component has been generated. In this project, the Voxeljet VX200 HSS system is used, which has an installation space of 290 x 140 x180 mm. Larger components can be divided into segments and then joined. The process principle can also be easily scaled up to larger systems.
The overall objective is the efficient and sustainable use of additive manufacturing processes in the automotive industry, in the commercial vehicle sector or in related industries with similar challenges. In terms of this process, this can only be achieved through research along the entire process chain from the initial idea to the reuse of waste powder. Thanks to the open machine concept, we can influence a large number of process parameters and thus, for example, independently qualify new materials or optimize known materials. Since no support structure is required for this process, complex components with a very high lightweight construction potential can be realized with a constant layer time. In industrial use, this makes it possible to generate optimized components for various applications in an uncomplicated manner. An example of this is current research on components with an internal lattice structure, which are subsequently filled with aerogel. Such a composite material may be particularly suitable for thermal and acoustic insulation in vehicles. In order to maximize the sustainability of the process and at the same time increase economic efficiency, the aging of the powder is also being investigated in addition to structural optimization in order to be able to add as much recycling powder as possible to a new process.