Fasteners and Sealing
Fig. 1. MAN Truck & Bus AG is constantly looking for new solutions to reduce fuel consumption, exhaust emissions and noise level. The MAN TGX 18400, for example, received the ‘Green Truck 2011’ award.
Photo courtesy MAN
Chrome free surface coatings for bolts and other fasteners
Rudolf Knott and Dr Jochen Schneider look at the benefits of using a chrome (VI)-free coating for the surface protection of high-strength steel fasteners
C
ommercial vehicle manufacturer MAN will from now on be using a chrome (VI)-free coating from Dörken for the surface protection of high-strength steel fasteners. Its layered structure made up of a zinc flake coating
with co-ordinated post-lubrication achieves the specified high level of corrosion resistance and fulfils at the same time the coefficient of friction requirements. MAN Truck & Bus AG of Munich is the largest company
in the MAN Group and one of the world’s leading suppliers of commercial vehicles and transportation solutions. As a pioneer in all areas of relevant technology, the company is constantly looking for new solutions to reduce fuel consumption, exhaust emissions and noise level. The MAN TGX 18400, for example, received the ‘Green Truck 2011’ award, having impressed judges with the lowest level of fuel consumption and CO2
emissions on the European market. However, ecological accomplishments have taken a high
priority at the company for many years. Regular internal and external audits are, for example, run at every production site
in order to review the environmental protection measures in place and to continually improve the company’s sparing use of water and material resources and the reduction in air pollutants. Some of these measures are concerned, for instance, with reducing use of coolants and lubricants and the associated consumption of water, while others relate to optimising fasteners’ anti-corrosion coating from a ‘green’ perspective.
Responsible decision-making
Although EU Directive 2000/ 53/EC, which has been in force since July 2007, does not apply to vehicles over 3.5tons, MAN decided to switch surface coatings for all bolts and other fasteners to chrome (VI)-free alternatives. This decision was, of course, taken partly to reduce the risks to human being and the environment. However, commercial and logistical considerations also played a part. That’s due to the fact that at every stage of the production process right through to assembly chrome (VI)-free parts have to be strictly separated from parts with a chrome (VI) content. And a
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