4M Knowledge base - papers

T. Rechtenwald (a), A. Kopczynska (b), E. Schmachtenberg (b), M. Devrient (a), T. Frick (a), M. Schmidt (a)

(a) Bayerisches Laserzentrum GmbH, Konrad-Zuse-Str. 2-6, 91052 Erlangen, Germany
(b) Lehrstuhl für Kunststofftechnik, Friedrich-Alexander Universität, Erlangen, Germany

Abstract

Decreasing sales figures and increasing demand of different variants at the same time, as well as the desire of a short time to market pose a challenge for nowadays manufacturing technology. In this context, a new flexible production technology for mechatronical devices, which include also optical functions, called Embedding Stereolithography (eSLA) is introduced. eSLA combines the flexibility to automatically generated inner and outer complex geometries of conventional SLA with embedded functional components, which are conducted by generative manufactured electrical and/or optical structures. To form a rugged mechatronical device out of mechanic and/or electronic parts by eSLA a sufficient wetting of the used components by the processed liquid photopolymer is needed. Therefore the surface tension and viscosity of different photopolymers is measured and compared to surface energies and surface roughness of relevant component materials. Afterwards the characteristics of wetting of the chosen photopolymers on these materials are discussed.

T. Hanemann (a,b), K. Honnef (b), J. Hausselt (a,b)
a Forschungszentrum Karlsruhe, Institut f. Materialforschung III, D-76021 Karlsruhe, Germany
b Albert-Ludwigs-Universität Freiburg, Institut f. Mikrosystemtechnik (IMTEK), D-79110 Freiburg, Germany

Abstract

Different variants of reaction molding techniques like UV-embossing, UV-RIM, Photomolding, a.o., exploiting the rapid light induced photopolymerization of reactive resins are widely used in microsystem technologies for the fabrication of microoptical components or for rapid prototyping purposes. The solidification based on photocuring limits the suitable materials to transparent resins and yields only plastic microstructured parts. In this paper the further development of micro reaction molding with respect to a rapid prototyping of ceramic and metal parts will be described. As in the different variants of powder injection molding additional process stages have to be considered and individually optimized. First a free-flowing reactive resin based composite with a large filler load (microsized ceramic or metal powder) of at least 45 vol% has to be prepared. The addition of suitable thermal initiators allows the solidification of the composite subsequently after mold filling in a molding tool equipped with microstructured mold inserts. The mold filling and hence the accurate reproduction of surface details depend strongly on the composite’s viscosity, which is a function of the filler load. The further process stages like debinding and sintering have to be optimized with respect to the polymer based reactive resin used and the ceramic filler. Especially an improved process control of the composite formation prior to molding and the thermal debinding is crucial for the realization of ceramic or metal parts carrying a microstructured surface. The development of the whole process chain and some microstructured ceramic or metal parts will be presented.