Research Article

Evaluation of experimental and numerical investigations into micro-hydroforming of platinum tubes for an industrial application

¹ Cologne University of Applied Sciences, Betzdorfer Str. 2, 50679 Cologne, Germany
² Heraeus Precious Metals GmbH & Co. KG, Heraeusstr. 12–14, 63450 Hanau, Germany

^* e-mail: christoph.hartl@fh-koeln.de

Received: 10 April 2014
Accepted: 17 September 2014

Abstract

The presented results are based on an experimental feasibility study which was carried out for the application of micro-hydroforming in the manufacture of micro-sized products made from the material PtIr10. Within the scope of this product development, the prediction of feasible and failure-free expansions was one major aspect. This paper deals with the analysis of the failure cases which limited the expansions due to necking. The experimental investigations have shown a scattering of the forming results which was due to so-called size-effects resulting from the material grain structure. Simulations with the finite element method were used to determine the development of stresses and strains within the hydroformed tube. It was demonstrated that a superimposition of axial compressive stresses reduces the influence of size-effects and increases the feasible expansion diameter. Using these simulations, the applicability of an existing failure criterion to estimate a mean forming-limit was verified.