Innovative Joining Technologies are the Key to Lightweight Automotive Construction
Many sectors, especially the automotive sector, are ever more intensively tapping into the great potential of aluminium lightweight construction. The strategy long pursued by the major automobile manufacturers has been to use “the right material in the right place”. This is why they have been pushing ahead with the smart, flexible handling of the most varied of materials with the aim of using the best suited raw material for every purpose in automobile construction.
Multi-material design using steel, aluminium, fibre composite materials or even magnesium is the rule today. The key to success for material mixes is the connecting and joining technology. To be able to securely join a variety of materials into so-called multi-material modules new and efficient joining processes are being used. Here each car model with its relevant material system determines which joining technology is deployed.
For car bodies the major automotive manufacturers use the most diverse joining methods. The different methods are as follows:
- thermal joining techniques: resistance spot welding, MAG / MIG welding, laser beam welding / brazing, arc stud welding, plasma welding / brazing, MIG brazing, friction stir welding
- mechanical joining methods: folding / flanging, clinching, punch riveting, direct screwing
- chemical joining process: bonding
Number of Joining Technologies on the Rise
To join the new raw material pairings comprehensive process understanding and know-how is required. For this reason, processes are being developed to optimise bonding, riveting and screwing technologies. Indeed, lightweight construction materials are prompting an increase in joining processes. For instance, carmaker Audi uses a total of 19 different joining technologies in the car body construction of its models.
The challenges facing joining technology in the automotive sector are numerous: large temperature and humidity fluctuations, great variance in application and use (road surfacing and conditions, dust etc.) as well as individual user behaviour. In many joining applications for multi-material design, thermal bonding technologies cannot be used because the lightweight materials to be joined are too heat sensitive and require cold processes. This applies, for example, to composite materials with hot-formed steel, aluminium alloys or fibre composites.
Innovative mechanical joining technologies are not only gentle on raw materials but often also offer other advantages like speed, one-sided accessibility, low maintenance and energy savings.
No one joining technology is suitable for all areas of application and all materials. However, comprehensive process understanding is required to develop the appropriate joining solution for the construction innovations of multi-material designers. There are many factors to consider, such as:
- Accessibility of the components
- Corrosive behaviour of the materials
- Expansion coefficients of the materials
- Processing time
- Number of layers to be joined.
If a component is accessible only from one side, for example, the punch rivet option is eliminated, because in this case the joining tool would have to reach the joint from above and below. An alternative in this case would be flow drilling, which makes dynamically secure and detachable multi-material connections possible.
Another trend in the automotive industry, and the basis for more sustainable mobility, are new drive concepts, such as purely electric or hybrid drives. These also require new joining solutions because the smart installation of a battery can improve its longevity, performance and safety.
Welding and Joining Pavilion at ALUMINIUM 2018
Providing information on joining technologies, plants, machinery, equipment and accessories for aluminium joining at ALUMINIUM 2018 is the Welding and Joining Pavilion in Hall 9. Exhibitors featured here present their solutions for welding, bonding, brazing and other mechanical joining processes.
Find here the full exhibitor list of ALUMINIUM 2018.