Affiliation:
1. LABEIN-Tecnalia Research Center
2. Ohio State University
Abstract
Hemming is the last or one of the latest stage operations for the stamped parts. For this
reason it has a critical importance on the performance and perceived quality of assembled vehicles.
It is used to attach two sheet metal parts together or to improve appearance creating a smooth edge
rather than a razor edge with burrs.
However, designing the hemmed union is not always easy and is deeply influenced by the
mechanical properties of the material of the bended part. Main problems for the automotive industry
arise when bending aluminum alloys.
Aluminum sheet is more difficult to hem due to its susceptibility to strain localization during the
hemming process. This phenomenon produces cracking on the hemmed edge [1].
In order to avoid this problem and due to the limitations of conventional flanging and hemming
technologies, the flange radii must be increased and a rope hem used (instead of the flat hem used
with steels) when working with aluminum alloys. These changes on the design of the hem union
give as a result a lower quality final product [2].
Dies and tools used for the hemming process are designed based on experience and on lengthy and
costly die tryouts.
Continuing with the development of new applications for the Electromagnetic Forming (EMF)
technology, LABEIN-Tecnalia and Professor Glenn Daehn’s group from The Ohio State University
carried out some first straight flat hemming experiments using the AA 6016 T4 aluminum alloy.
The results obtained from these first trials are presented in this paper giving a first sight of the
possibilities, advantages and disadvantages of using the Electromagnetic Forming technology for
the hemming of aluminum sheet panels.
Using a non-clouped FEM simulation method, the experimental results are compared to the ones
obtained with the simulations.
The future working line in developing this new application for the Electromagnetic Forming
technology will be based on the results obtained by this study.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,General Materials Science
Reference3 articles.
1. John E. Carsley: Microestructural evolution during bending: Conventional Vs. Roller hemming, Trends in materials and manufacturing Technologies for transportation industries and powder metallurgy research and development in the transportation industry, Materials Processing & manufacturing division, 6th global Innovations Proceedings, TMS Annual Meeting, San Francisco, California, USA, February 13-17, 2005. pp.169-174.
2. S. Golovashchenko, Sharp flanging and flat hemming of aluminum exterior body panels, Journal of materials engineering and performance, Vol. 14, August 2005, pp.508-515.
3. H. Livatyali, A. Muderrisoglu, M.A. Ahmetoglu, N. Akgerman, G.L. Kinzel, T. Altan, Improvement of hem quality by optimizing flanging and pre-hemming operations using computer aided die design, Journal of Materials Processing Technology 98, 2000, pp.41-52.
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