IIW White Paper

The productivity in EB welding has been increased drastically by introducing several chambers for loading and unloading of work pieces from a separate chamber that is evacuated before the work piece is transferred into the welding chamber ( Figure 5.4 ).

Figure 5.4 EB welding system with loading and unloading chambers linked to the vacuum chamber for welding (Reproduced courtesy: B. Pekkari)

Loading Evacuating Processing Venting Unloading

Recently, out-of-vacuum and reduced pressure EB welding has been further developed. Not only heavy sections are EB-welded but thin sheet parts for the automotive industry e.g. an aluminium hollow section is welded with 12 m/min in Non-Vacuum EB-system. Such a system is highly recommended when high weld speeds and short cycle time are required from 1 up to 10 mm in thickness. There are test results showing that welding speeds for Al and steel with t=1 mm of 60 m/min and 45 m/min respectively are possible to achieve. EB welding applications will definitely increase thanks to the progress in technology. Currently there are about 3,000 EB-installations in the world. 800 of these are in USA, 1,300 in Asia, 700 in Europe plus 200 in the former Soviet Union and 22 units installed in Sweden. 5.1.3 Laser beam welding The laser beam welding process has long been used in various industrial sectors, including automobile, ship- building and aerospace applications. These applications are driven by cost and weight efficiencies achieved in the welded structures. Both CO 2 and Nd:YAG welding processes are capable of producing structural welds with narrow weld and HAZ regions having high quality. Due to the rapid cooling, most structural C-Mn steels respond with weld zones of high hardness, while austenitic steels provide welds without any hardness increase. Recent developments in high-power lasers and robotic control have accelerated the application of the LBW process for car-body fabrication and assembly, for example through so-called “remote welding”. LBW has the advantage of single-sided access, high welding speeds and precision while providing consistent weld integrity and a low heat input which yields reduced distortion. Unlike conventional resistance spot welding, laser spot welding (LSW) is a single-sided, non-contact process and as a result, LSW can be a very attractive joining method for automotive mass production. Various factors need to be considered, however, when replacing one joining method by another. 5.1.4 Laser hybrid welding The number of laser welding and especially laser hybrid welding applications is growing fast. The laser welding process is already common in the automotive industry. The most impressive installation with 150 YAG lasers on 4 kW each and one 1 kW at Volkswagen are connected to 250 welding and three cutting heads. In this line production for the GOLF V, 70 meters are laser welded and brazed while there are only 7 meters of arc welds per car. With the further development and introduction of the laser hybrid process ( Figure 5.5 ), the possible number of applications for construction will increase significantly.

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Through Optimum Use and Innovation of Welding and Joining Technologies

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