Reliability in generative manufacturing

© Photo Felizitas Gemetz/Fraunhofer IWM

A generatively manufactured and bionically inspired chair's load-bearing capacity is being tested at the Fraunhofer IWM. Model size: 40% of original.

Generative production processes are becoming more important in the production of small series, customized components and the manufacture of complex component structures. The transition from rapid prototyping to rapid manufacturing requires that produced parts be subjected to reliable and defined quality control. To do this, we experimentally and computationally define the internal stresses and shape distortions that arise from the layered structure of components in selective laser melting (SLM) processes or in stereolithography. Using finite elements methods and “computer aided optimization”, we also investigate the mechanical properties of complex structures which can be produced through generative processes. Load-oriented and function-optimized design make functional components for the “Internet of things” possible.

Jaeger, R.; Koplin, C.; Brand, M.; Meiners, W.; Jansen, S.; Improving the Reliability in Rapid Manufacturing of metallic Components, in Proc. of Euro-uRapid 2007, International User’s Conference on Rapid Prototyping and Rapid Tooling and Rapid Manufacturing (2007)

Koplin, C.; Gurr, M.; Mülhaupt, R.; Jaeger, C. R.; Shape accuracy in stereolithography: A material model for the curing behavior of photo-initiated resins, in Proc. of Euro-uRapid International 2008, User’s Conference on Rapid Prototyping and Rapid Tooling and Rapid Manufacturing (2008) 315-318 Link

Subtopics

Design for generative manufacturing technology and bionic structures

Biomimetic structures inspired by nature can be easily produced with additive manufacturing processes due to their geometry. As a demonstration of a generatively manufactured component with a cell structure, a bionically designed cantilever chair was designed at the Fraunhofer IWM. Software was specially developed for “computer aided optimization (CAO)”, which efficiently evaluates the cellular structure of even large components and optimizes the loads accordingly

Artificial venous systems and blood vessel replacement

Supplying tissue with nutrients through a venous system (vascularization) is a current challenge in tissue engineering. The Fraunhofer IWM is involved in projects whose goal is additive manufacturing of a vascular system to supply tissue grown in vitro. We determine the optimum topology of the vascular system and optimize the local geometry of the branches to achieve optimal fluid mechanical flow conditions. The mechanical properties of artificial blood vessels and the diffusion of nutrients through hydrogels and nonwovens to supply cells are experimentally investigated. The artificial blood vessel system should make the “biofabrication” of tissue models and transplants possible in the future. 

The customer as designer

Additive manufacturing processes are becoming a significant driver of participatory production, “mass customization” and “open innovation.” Individualized products or replacement parts can essentially be designed by anyone on a computer and then generatively manufactured with their own 3D printer, in a fab lab, or by a contract manufacturer. But not everyone is a capable engineer or a good designer. We are working on the foundations for software tools that simplify the load-oriented design of components by the end user.