Moving more with Less CO₂ - Bonding in the Automotive Industry

The motor car has been with us for more than 120 years. Initially it was expensive and exclusively for the wealthy, but gradually it became available to the masses. Now it is hard to imagine life without the motor car. It has transformed our way of life, our landscape, and our outlook. Worldwide it has provided mobility, pleasure and economic opportunity to millions of people, but its widespread use has damaged the environment. Now the big question is how sustainable is the motor car, and the way we use it?

Emissions from passenger cars account for around half of all CO₂ emissions in the transport sector, and almost 12% of total CO₂ emissions in the European Union. For this reason the European Commission introduced a comprehensive strategy to reduce CO₂ emissions from new cars and vans sold in the European Union, to ensure that the EU meets its greenhouse gas emission targets under the Kyoto Protocol and beyond.

To meet the targets requires some fundamental changes in the way cars are assembled, used, and - ultimately - disposed of. Adhesive bonding is one of beneficial factors in car production since it helps to reduce the vehicles weight, and thus also the CO₂ emission, of the finished car. Moreover, it has also proved to be the most energy efficient joining technique.

A lighter car emits less CO₂. But modern cars also need to display ever more innovative and functional designs and continously improve the safety of the passengers.

In order to achieve these various goals, whilst also limiting the overall weight of the car, many different materials - such as aluminium, magnesium, steel, or fibre-reinforced plastics - need to be used. Joining all these different parts and materials to make a complete car can only be done with the help of adhesives, since traditional joining techniques like welding, riveting and clinching might damage the material and cannot be applied on all substrates.

Increasingly, vehicle manufacturers are using plastic in doors and other vehicle body parts, while most use plastic in bumpers. Tooling for plastic components generally costs less and requires less time to develop than that for steel components and therefore may be changed by designers at a lower cost, making it an attractive material for vehicle makers, despite its higher cost per kilogram. The relative low weight also contributes to higher fuel efficiency in cars. Not only the car body, but many exterior and interior components, visible or hidden in a car, owe their functionality to state-of-the-art adhesive technologies.

Overall the energy spent per bonding application with adhesives is lower than the energy spent for conventional joining techniques like welding or clinching. A study, comparing the different joining technologies like spot welding, laser welding, clinching and bonding, found that adhesive bonding achieved the same, or even an increased strength of the joint with less energy spent.

Adhesive bonding increases the choice of material used and enables more innovative designs; both are important factors for the safety of the car.

For example, the windscreen provides structural strength to the car body and helps keep passengers inside the car if an accident should occur. As important as the windscreen quality is, so too is the quality and proper installation of the auto glass adhesive.

The use of adhesives in car production helps to improve the safety standards and allows modern design with innovative material. They help the car industry to meet their challenges of developing more environmentally friendly solutions for the future.

And what of the future?

Electric cars and also fuel cell cars are being promoted as part of a sustainable solution, but they still need fuel, and significant CO₂ reduction would require electricity to be generated from non-fossil sources, However, electric vehicles may be important in reducing localised pollution. In any case such cars nedd als significant weight savings to increase their range.

Fuel cells represent the latest and, perhaps, the most rewarding of alternative energy technologies. The fuel cell is a power-generation system in which hydrogen is used as a fuel source. The hydrogen can be extracted from fractionated hydrocarbons (e.g., gasoline, methanol, propane) or natural gas with what is called a reformer. Hydrogen can also be produced from the electrolysis of water.

Tighter reliable, fail-safe sealing of the elecrical components is an absolute necessity in electric and fuel cell technology. The adhesive or sealant must be adaptable for high volume, mass production and have low assembly costs.

Whatever direction the motor vehicle industry takes in the coming decades, it is certain that adheisves and sealants will have an increasing part to play.

ANNEX I - Weight reduction

Due to new functions installed on the cars, the weight of vehicles is steadily increasing. The current average weight of a car in Europe is around 1.350 kg, producing around 180 g CO₂, while in the USA it is 1.850 kg at 210g CO₂.

Crash resistant lightweight structures is one route to achieve better mileage and emissions, which has to be complemented by more efficient combustion engines, hybrids and/or e-drive, lower friction tyres, better aerodynamic shaping etc. The use of adhesives is enabling the development of new technologies in all these sectors with good resultd on weight reduction.