The steering-angle sensor that component manufacturer Bosch produces for various international car manufacturers is now being made of BASF’s easy-flowing Ultradur High Speed polybutylene terephthalate (PBT).
This plastic allows injection moulders not only to markedly shorten the cycle times, but also to make components of detailed filigree design. The steering-angle sensor plays an integral role in the safety of vehicles and provides the electronic stability programme (ESP) with information about the position of the steering wheel. This is why this part and its electronics are located directly on the steering column.
Following the first sensor generation made of Ultradur B4300 G4 LS High Speed PBT, made up of 20% glass fibres, Bosch recently went into serial production with its newly developed sensor for the latest generation of automotives. In view of the ever-growing requirements being made in terms of space, the new steering-angle sensor had to have even thinner walls and detailed filigree construction than its predecessor.
When standard PBT is used, only one-third of the intricate injection-moulding tool can be filled. In contrast, with the easy-flowing Ultradur High Speed PBT, whose good processing properties are due to BASF’s specially devised nanotechnology, the sensor can be manufactured without any problems.
Further, the steering-angle sensor made of this plastic can be laser-written with a high degree of contrast, so that the parts can be marked with very fine so-called data matrix codes containing a wealth of information about the part on a very small surface area.
Since the material can replicate details very precisely, thereby adhering to Bosch’s narrow tolerances, the sensor can be configured very flexibly, depending on the car model and on the desired functionality. This BASF PBT has also successfully made the transition from screw-in to snap-on connections. This material has now been approved for use at all Bosch facilities worldwide.
The BASF PBT, which has been modified with a special nanoadditive, serves to replace a standard PBT. The improved flow of this product allows users to lower the processing temperature as well as the injection and holding pressures in the injection moulding machine.
Energy savings of up to 20% can be attained and the cycle time can be reduced by up to 30%. As an alternative, the tool can have a simpler design and new components can have thinner walls, which translates into considerable material savings. The number of rejects also drops since the tool can be filled more easily with this easy-flowing plastic.