For welding of conventional structural steels semiautomatic technologies (MIG, MAG) are widely used, whereas for welding of Al-alloys and stainless steels the TIG welding method is the most common. The current study concentrates on welding of thin sheet metal products from stainless steel and aluminium by using a novel cold metal transfer (CMT) process. The CMT technology is an alternative to TIG, providing advantages, such as reduction of distortions and increased productivity. This is mainly due to low heat input, achieved by controlled movement of the electrode. In order to realize these advantages, optimization of the CMT welding process is essential. The aim of this study was the optimization of the process using the existing welding equipment (robot, manipulator, etc) and validation of the CMT process. The limiting factors for the increase of the productivity are the reduction of quality (increase of porosity, distortions and inacceptable shape of the welding bed). As a result, practical recommendations are given for the implementation of the CMT technology for robotic welding.
1. Bachorski, A., Painter, M. J., Smailes, A. J. and Wahab, M. A. Finite element prediction of distortion during gas metal arc welding using the shrinkage volume approach. J. Mater. Process. Technol., 1999, 92–93, 405–409.
http://dx.doi.org/10.1016/S0924-0136(99)00161-2
2. Wu, C. S., Zhang, M. X., Li, K. H. and Zhang, Y. M. Numerical analysis of double-electrode gas metal arc welding process. Comput. Mater. Sci., 2007, 39, 416–423.
http://dx.doi.org/10.1016/j.commatsci.2006.07.004
3. Blondeau, R. Metallurgy and Mechanics of Welding Process and Industrial Applications. Wiley-ISTE, 2008.
http://dx.doi.org/10.1002/9780470611272
4. http://content.lincolnelectric.com/pdfs/products/automation/mc04179.pdf (05.06.12).
5. http://www.fronius.com/cps/rde/xchg/fronius_international/hs.xsl/79_9399_ENG_HTML.ht (20.05.12).
6. Pickin, C. G. and Young, K. Evaluation of cold metal transfer (CMT) process for welding aluminium alloy. In Science and Technology of Welding and Joining, 2006. Maney Publishing, 11/5, 583–585.
7. Zhang, H. T. and Feng, J. C. The arc characteristics and metal transfer and its use in joining aluminium to zinc-coated steel. Mater. Sci. Eng., A, 2009, 499, 111–113.
http://dx.doi.org/10.1016/j.msea.2007.11.124
8. ISO 5817:2003. Welding. Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded). Quality levels for imperfections.
9. EVS-EN 1011-1: 2009. Welding. Recommendations for welding of metallic materials. General guidance for arc welding.
10. Outokumpu Welding Handbook. First Edition, Sandvikens Trykeri AB, 2010, 138.
11. EVS-EN 573-3:2009. Aluminium and aluminium alloys – Chemical composition and form of wrought products – Part 3: Chemical composition and form of products.
12. EVS-EN 485-2:2008. Aluminium and aluminium alloys – Sheet, strip and plate – Part 2: Mechanical properties.
13. EVS-EN ISO 14175:2008. Welding consumables – Gases and gas mixtures for fusion welding and allied processes.
