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S. Baumgartner, J. Stampfl:
"Digital Materials: A combination of Inkjet and Stereolithography";
Talk: TheIJC USA 2018, Chicago; 2018-04-12 - 2018-04-13.

In the past years, a variety of new additive manufacturing technologies (AMT) have appeared on the market. AM provides multiple advantages over conventional manufacturing methods and has therefore developed into a promising technology for various applications. Drawback of most commercially available systems, however, are the insufficient mechanical properties and the limited resolution of the printed parts. With industry calling for tougher and stronger materials, especially for engineering applications, we developed a hybrid 3D-printing technology, allowing us to exploit the advantages of two common AMTs and simulate the toughening mechanisms of natural structures like marine material. A self-developed stereolithography (SL) process provides the basis of the printer. Based on the principal of digital light processing (DLP) a viscous resin is cured layer-by-layer in a material vat, forming the matrix of the part. As a second system an inkjet printhead comes into game. With this, a pattern of ink droplets can be selectively placed after each layer of the printed parts, allowing us to process highly viscous photocureable resins with high resolution and excellent surface quality and mimic the properties of natural structures by jetting thin layers of soft material into a hard matrix. Those so-formed "digital materials" show promising results regarding enhancement of the thermo-mechanical properties, as first experiments indicate an increase of the strain at break and impact strength by over 50% and 40%, respectively - compared to the plain matrix material. The usage of the inkjet system allows further modifications of the printed parts in a way which has not been feasible up to now: conducting tracks inside complex shaped parts, surface modification with inorganic materials, customized coloring and other multimaterial approaches can be established.