French automotive supplier Valeo has developed a top column module whose housing and levers are made of BASF’s engineering plastics Ultramid (PA) and Ultradur (PBT).
Used by the BMW Group in its vehicles with rear-wheel drive for the BMW 3 to 7 series, the new column is around 20 percent lighter than the previous model.
For the indicator and windshield wiper levers, Valeo uses the surface polyamide Ultramid B3EG10 SI (SI= surface improved). For the two-part core module it employs the PBTs Ultradur B 4520 and Ultradur B 4300 G4. The latter is processed by the company Buck Spritzgussteile Formenbau, Flachslanden, Germany, using the MuCell process.
The surface polyamide, highly filled with 50 percent glass fibres, is stable and UV-resistant. It was originally developed for the furniture industry, where it is now used in numerous design and office chairs.
“We were initially slightly surprised that BASF offered us a material developed for furniture,” said Jochen Foeßel who is responsible for part optimization and plastic injection moulds at Valeo. “But we were won over by the homogeneous, shiny surface finish as soon as we saw it. And the excellent mechanics and UV resistance were confirmed in the tests we did.”
Valeo carried out the tests on the resistance of car interior components in accordance with DIN EN ISO 1043-1/GS 93016.
The two-part core of the top column module is made of different Ultradur grades. The lower carrier housing made from Ultradur B 4300 G4, which is reinforced with 20 percent glass fibres, is manufactured by the company Buck Spritzgussteile Formenbau using the MuCell process. In this physical foaming process, nitrogen is added to the polymer melt during injection-moulding, which leads to the formation of a foam structure. As a result, the weight of the component is reduced by around ten percent and the dimensional stability is increased without any adverse effect on the high rigidity and excellent chemical resistance of the material. The upper top column module housing, on which the steering wheel is mounted, is made from the unreinforced PBT Ultradur B 4520, noted for its low water uptake and therefore high dimensional stability and appealing surface finish – a combination of properties ensuring that the steering wheel can be mounted safely on the top column module.