The concept of cascaded recycling cycles. (c) Graphic: UBT / Engineering Design & CAD.
Additive manufacturing (3D printing) is currently gaining considerable importance in all sectors of industry. With this technology, high-quality everyday products, some of which fulfil very complex functions, can be manufactured from a single material in a short process chain. The material and energy consumptions are thus considerably lower than for products that are manufactured with conventional methods from various materials and in correspondingly extensive processes. "The unsolved challenges, however, concern reuse. This is exactly where the MonoMat project comes in. Our goal is to recycle the materials used in the additive manufacturing process as completely and repeatedly as possible, so that they become part of a cross-industry, ecological, circular economy," says project leader Prof. Dr.-Ing. Stephan Tremmel, who is Chair of Engineering Design & CAD at the University of Bayreuth. Moreover, the Chair of Manufacturing and Remanufacturing Technology, Prof. Dr.-Ing. Frank Döpper, and the Chair of Biomechanics, Prof. Dr. Franz Konstantin Fuß, are also involved in MonoMat.
A new cascade model
The project focuses on the material class of polymers and their applications in medicine, sports and lifestyle. Especially in these areas, numerous products must be adapted to the individual requirements and wishes of the customers, and so contribute to an increased quality of everyday life. Examples are soles for running shoes, cleats, shin guards, prostheses, and orthoses. For the design, production and recycling of such products, Bayreuth scientists have conceived a cascade model that interlocks medicine, sport, and lifestyle, and links various high-tech processes: High Speed Sintering (HSS), Laser Sintering (LS), Extrusion Additive Manufacturing (EAM), and injection moulding.
At the beginning of the cascade model is the additive manufacturing of products that must be of outstanding quality for individualised applications in medicine. The sintering processes HSS and LS are used to this end. When the products are no longer usable, the material is recycled. Depending on its condition, it is reprocessed into medical products, or it is used in sports or lifestyle products – in other words, in areas where the qualitative requirements for material properties are easier to meet. Recycled material is also available for material extrusion (EAM). In this process, it is reused as often as necessary until it has finally outworn. Then it can be reused for injection moulding in mass production.
Lightweight design demonstrators emerging as concrete applications from the cascade model are to explore the possibilities and limits of this new approach. The interdisciplinary cooperation between engineering and sports sciences on the Bayreuth campus ensures that the functions of the products important to their customers, and resource-saving, environmentally friendly manufacturing processes are optimally coordinated.
Contributing to climate protection
A special aspect of the project is the calculation of the greenhouse gas emissions that can be saved in the future through the application of the cascade model. For these forecasts, the Bayreuth scientists intend to use a method that not only takes into account the respective materials and production processes, but also recycling and ecological effects such as by-products and waste. In this way, the MonoMat project aims to show the practical benefits the combination of lightweight design and additive manufacturing can have for climate protection.
Cooperation with industry partners
Partners of the University of Bayreuth in the MonoMat project are Neue Materialien Bayreuth GmbH, AM Polymers GmbH in Willich, Oechsler AG in Ansbach, and Hans Weber Maschinenfabrik GmbH in Kronach. Three other companies are associated with the project: rahm Zentrum für Gesundheit GmbH in Troisdorf, Aevolution in Bayreuth, and Headis GmbH in Kaiserslautern. For the research, development, and use of additive manufacturing, the University of Bayreuth already established the Campus Additive.Innovationen (CA.I) research centre in 2020, where scientists from five faculties work together with industry partners on innovative solutions.
Contact for scientific information:
Prof. Dr.-Ing. Stephan Tremmel
Chair of Engineering Design and CAD
University of Bayreuth
Phone: +49 (0)921 / 55-7194
E-mail: stephan.tremmel@uni-bayreuth.de
