It is an old cliche, but a consortium of companies really has reinvented the wheel. A ground-breaking new design of off-road wheel disc has been developed using advanced high strength steels (HSS) that are up to four times stronger than ordinary mild steel. Successful research based on the premise that doubling the strength of a product allows the material thickness to be reduced by one third has allowed the creation of a prototype that is 30% thinner and 30% lighter than a conventional wheel disc.
The collaborating companies, GKN Wheels, Corus and SSAB Swedish Steel, believe that this is the first off-highway wheel disc to use HSS. The wheel is more cost-effective and environmentally friendly than those made from mild steel. One of the main drivers behind the development of this wheel disc was the increasing specifications of agricultural, construction and other off-road vehicles. This has meant rising vehicle weight, at a time when the supply chain needs to cut weight and costs to make vehicles more fuel efficient.
The disc uses advanced HSS with minimum tensile strengths typically ranging between 400 N/mm2 and 1,400 N/mm2, and yield strengths in excess of 550 N/mm2. Mathematical modelling proved that the disc gauge could be significantly reduced from 12.5mm to 8mm by substituting grade 550 hot rolled steel for grade 355 material, and adding stiffening ribs for rigidity. Cyclic fatigue tests gave positive results, and sample discs were successfully produced from 8mm hot rolled material in grades 500, 550, 600 and 650.
Paul Taylor from Corus said, ‘This new disc will help to maximise the load-bearing capacity and fuel efficiency of the vehicle. We have also succeeded in reducing total supply chain costs, which provides a significant competitive advantage.’
The HSS wheel disc prototype was unveiled at the Agritechnica 2003 exhibition in Germany last month, and the group are now looking to bring the new disc into full production.