41
Through Optimum Use and Innovation of Welding and Joining Technologies
Improving Global Quality of Life
5
Needs and challenges in welding and joining technologies
5.1.7
Structural adhesives
Structural adhesives are not a threat to arc welding but gluing is growing and mainly used in large scale in the
automotive industry. One has to keep in mind that there are several types of gluing, such as; adhesive types,
structural adhesive, hem-flange adhesive, weld-through sealant and anti-flutter adhesive. The important
points for the process when used in cars are:
improved fatigue properties,
increased rigidness and,
improved collision properties.
The previous version of the Volvo S80 had 5.5m of glued joints while the latest one has 26 meter and is 7 kg
lighter. These figures can be compared with the length of welds in the BMW 7-series with 150 m, Audi A6
with 122 m and VW Golf V with 30 m.
5.1.8
Composites
Advanced materials such as composites are challenging the supremacy of metals in structural applications
due to weight reduction demand in various industrial sectors. In particular the aircraft industries are making
drastic changes in the use of materials. The share of aluminium on an aircraft has fallen from 70 % in the
Boeing 777, the previous commercial jet launched, to just 20 % on the Boeing 787. The Airbus has made a
similar switch from aluminium to composites in the fabrication of A350 aircraft. The main reason for doing
this is to make the aircraft more fuel-efficient and cheaper (less inspection) to operate. Representatives
from the aerospace and aircraft industries are stating that:
Joining
in the commercial aircraft industry will continue to be a technology area that can make a
major contribution to the industry.
Materials technology
is moving forward quickly and the associated processes must evolve with it.
Metal joining
remains a challenge but alternative materials such as composites, ceramics and
thermoplastics can offer significant potential.
Key technology area
-
Joining of dissimilar materials is a growing challenge.
The market for composites including fibre-glass has an annual growth of 5.5% in the world. The Asian
market is very vibrant and growing with 9.9% p.a. The total market was forecast to be more than £24 billion
year in 2010. The huge market covers applications such as tanks and pipes, which are working in harsh
environments for storing and transporting corrosive materials. The total cost of metallic corrosion in the
US alone is estimated at $280 billion. China is today number two in this area but it will soon overtake the
current market leader USA.
Figure 5.9
Magnetic pulse
technology (Reproduced
courtesy: B. Pekkari)
