Laser-Assisted Bending


Article Preview

When sheets of high-strength (HS) and ultra-high-strength (UHS) steels are bent by a press brake the process suffers from large bending forces, considerable springback, and eventual cracks. Additionally, some unpredictable effects, such as lost contact to the punch, caused by strain hardening may occur producing a bend with erroneous radii. The strain hardening of the bending line may make further processes, such as forming or welding, more complex. One solution to these problems is to anneal the bending line with a laser in advance. Of course, it is also possible to utilise other types of heat sources, but the laser can offer the most precisely controlled heat treatment. The proper process parameters depend on the material, and it has been noticed that inadequate process parameters may harden the material instead of annealing. In this work some experiments on bending sheet metal samples of HS or UHS steel with previously laser-annealed bending lines have been carried out and the outcome analysed. The results show that the annealing produces better bending results compared to the conventional procedure. This includes lower springback, less hardening in the bending line and more precise geometry of the bend. It can be even suggested that proper annealing with strain hardening in bending will produce the original material structure. Obviously, more theoretical and experimental work is required to optimise the process parameters including the laser power and speed for each pair of material strength and thickness.



Main Theme:

Edited by:

F. Micari, M. Geiger, J. Duflou, B. Shirvani, R. Clarke, R. Di Lorenzo and L. Fratini




K. Mäntyjärvi et al., "Laser-Assisted Bending", Key Engineering Materials, Vol. 344, pp. 235-241, 2007

Online since:

July 2007




[1] Weisheit, A., Vitr, G., Scheffler, S. & Wissenbach, K.: Local laser heat treatment of ultra high strength steels to improve formability, [www-document], http: /www. msm. cam. ac. uk/phasetrans/2005/LINK/133. pdf. Read 8. 9. (2006).

[2] Geiger, M., Merkelein, M. & Pitz, M.: Laser and forming technology - an idea and the way of implementation, Journal of Materials Processing Technology Vol. 151 (2004), pp.3-11, ISSN 0924-0136.


[3] Schuöcker, G. Liedl, G. & Kratky, A.: Laser assisted forming a promising new application of high power lasers, [www-document], http: /info. tuwien. ac. at/iflt/igls_2003/16_Schuoecker. pdf. Read 8. 9. (2006).

[4] Merklein, M. & Geiger, M.: New materials and production technologies for innovative lightweight constructions, Journal of Materials Processing Technology Vol. 125-126 (2002), pp.532-536, ISSN 0924-0136.


[5] Neugebauer, R. Göschel, A., Sterzing, A., Kurka, P. & Seiferte, M.: Comparison of Material Behavior and Economic Effects of Cold and High Temperature Forming Technologies Applied to High-strength Steels, Proceedings of the International Conference SheMet 2005, UeticonZuerich, pp.101-108.


[6] Satorres, A.: Bending simulation of high strength steel by finite elements, Master's Thesis, University of Oulu, Department of Mechanical Engineering, 05. 05. (2005).

[7] Pitz, M. & Merklein, M.: FE Simulation of Laser Assisted Bending, Proceedings of the International Conference SheMet 2005, Ueticon-Zuerich, pp.745-752, ISBN 0-87849-972-5.

[8] Steen, W. M.: Laser Material Processing, Third edition, ISBN 1-85233-698-6.

[9] Metal forming handbook, Schuler GmbH, Göppingen 1998, ISBN 3-540-61185-1.

[10] Koljonen, M.: Developing a fine-grained austenitic stainless steel by cold rolling and annealing, Master's Thesis, University of Oulu, Department of Mechanical Engineering, 05. 04. (2005).