Improving Global Quality of Life
Improving Global Quality of Life
Improving Global Quality of Life
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The productivity in EB welding has been increased drastically by introducing several chambers for loading<br />
and unloading <strong>of</strong> work pieces from a separate chamber that is evacuated before the work piece is transferred<br />
into the welding chamber (Figure 5.4).<br />
Figure 5.4 EB welding system with loading<br />
and unloading chambers linked to the<br />
vacuum chamber for welding (Reproduced<br />
courtesy: B. Pekkari)<br />
Loading Evacuating Processing Venting Unloading<br />
Recently, out-<strong>of</strong>-vacuum and reduced pressure EB welding has been further developed. Not only heavy<br />
sections are EB-welded but thin sheet parts for the automotive industry e.g. an aluminium hollow section<br />
is welded with 12 m/min in Non-Vacuum EB-system. Such a system is highly recommended when high weld<br />
speeds and short cycle time are required from 1 up to 10 mm in thickness. There are test results showing<br />
that welding speeds for Al and steel with t=1 mm <strong>of</strong> 60 m/min and 45 m/min respectively are possible to<br />
achieve. EB welding applications will definitely increase thanks to the progress in technology. Currently<br />
there are about 3,000 EB-installations in the world. 800 <strong>of</strong> these are in USA, 1,300 in Asia, 700 in Europe plus<br />
200 in the former Soviet Union and 22 units installed in Sweden.<br />
5.1.3 Laser beam welding<br />
The laser beam welding process has long been used in various industrial sectors, including automobile, shipbuilding<br />
and aerospace applications. These applications are driven by cost and weight efficiencies achieved<br />
in the welded structures. Both CO 2<br />
and Nd:YAG welding processes are capable <strong>of</strong> producing structural welds<br />
with narrow weld and HAZ regions having high quality. Due to the rapid cooling, most structural C-Mn<br />
steels respond with weld zones <strong>of</strong> high hardness, while austenitic steels provide welds without any hardness<br />
increase.<br />
Recent developments in high-power lasers and robotic control have accelerated the application <strong>of</strong> the LBW<br />
process for car-body fabrication and assembly, for example through so-called “remote welding”. LBW has<br />
the advantage <strong>of</strong> single-sided access, high welding speeds and precision while providing consistent weld<br />
integrity and a low heat input which yields reduced distortion. Unlike conventional resistance spot welding,<br />
laser spot welding (LSW) is a single-sided, non-contact process and as a result, LSW can be a very attractive<br />
joining method for automotive mass production. Various factors need to be considered, however, when<br />
replacing one joining method by another.<br />
5.1.4 Laser hybrid welding<br />
The number <strong>of</strong> laser welding and especially laser hybrid welding applications is growing fast. The laser<br />
welding process is already common in the automotive industry. The most impressive installation with<br />
150 YAG lasers on 4 kW each and one 1 kW at Volkswagen are connected to 250 welding and three cutting<br />
heads. In this line production for the GOLF V, 70 meters are laser welded and brazed while there are only<br />
7 meters <strong>of</strong> arc welds per car. With the further development and introduction <strong>of</strong> the laser hybrid process<br />
(Figure 5.5), the possible number <strong>of</strong> applications for construction will increase significantly.<br />
38 <strong>Improving</strong> <strong>Global</strong> <strong>Quality</strong> <strong>of</strong> <strong>Life</strong> Through Optimum Use and Innovation <strong>of</strong> Welding and Joining Technologies