Polymeric materials

Polymer materials are used as photopolymers for stereolithographic processes, as extrusion material for 3D printing or in powder form for processing with laser sintering processes. All additive manufacturing processes have in common, that the choice of materials for the user is severely restricted compared with the material variety in injection molding. These are often highly specialized materials. The specific properties of these materials make processing even possible, i.e. in the laser sintering process. Therefore, developments concentrate on the one hand on making further materials accessible for processes and on the other hand on further developing the processes with the aim use standard polymers in future.

Polymers for Selective Laser Sintering

The process of selective laser sintering enables additive manufacturing of polymer components with properties similar to components produced by injection-molding. It is therefore an important process for functional components. The materials are used here as fine powders. Although the process is already established, the range of materials is severely limited; polyamides are mainly used. In addition to natural-colored standard powders, modified types are available, which - for example - have a higher flame resistance (used in the electronics industry) or have elastic properties in order to approximate the material behavior of other polymers.

New materials for the SLS process

Current developments in the field of selective laser sintering are concerned with the development of further polymer materials for this process. The market demands "authentic" materials. So far, the mechanical properties of polyamide powders have been modified in order to simulate the material sensitivities of other polymers. Developments focus on so-called commodities, such as polyolefins, which promise to enter the mass market. At the same time, high-performance technical polymers are being tested that can be processed with standard machines on the market. In addition to powder technology parameters, the rheology of the polymers, the kinetics of the melting and crystallization process and the energy input have to be optimized.

Bionic manufacturing

Additive manufacturing processes are characterized by the fact, that components are formed layer by layer. There are therefore analogies to natural growth processes of biological materials such as bone, tooth enamel and mother-of-pearl. In spite of the limited supply of materials, nature enables a variety of material properties that are often superior to technical systems. This is achieved by selective modifications and hierarchical structuring of the materials. A current research project aims to transfer these principles to additive manufacturing processes. For this purpose, methods of selective laser sintering are combined with printing techniques.

New processes for the preparation of fine polymer powders

Polymer powders available on the market today are produced using complex precipitation processes. Few materials are produced mechanically by cryogenic comminution processes. An economically and technically promising process is the high-pressure melt spraying process, in which the polymers in the molten state are atomized under the influence of supercritical carbon dioxide (scCO2) into fine spherical powders. In a current research project, the process is being developed and polymer powders are being tested in application.

Special materials - creative down to the smallest detail

Thermoplastics and natural materials such as wood and leather can be tailored to new applications, environmental aspects, novel or improved properties. By equipping them with additive, functional nano- and microparticles, microcapsules and hollow microspheres or hydrogels, a wide range of functions can be implemented.

Based on customer-specific requirements, the latest results of materials research or natural models, the institutes of the competence field develop strategies for new materials and test their industrial feasibility under ecological and economic aspects.