A perfect match
Our PULSE™ XT-series is well known at BMW and approved against the OEM’s specifications. For the new BMW 5 Series Touring we provide PULSE™ XT7215 for the lacquered roof pitch trims. BMW's supplier for these parts chose our mineral-filled PC/ABS mainly due to the low CLTE and the high dimensional stability of PULSE™ XT7215. The roof trim cover painted in piano black is mounted on a carrier made from a 20 percent glass-filled polypropylene that is overmolded with two lips made of TPS.
We could support the supplier to tackle a particular challenge in this project. Originally, it was planned to manufacture the exterior trim part from mineral-filled ABS resin. However, the tier had to switch to a mineral-filled PC/ABS resin in response to BMW’s demand for higher heat-resistant properties.
The trim application is intended to be used in a special version of the 5 Series Touring that has no roof railing system. It has a trapezoidal shape and must work well when mounted on a carrier part made from a 20 percent glass-filled PP – including two overmolded lips of TPS – that is fitted to the mounting of the roof rails to cover it. This structural element was already produced, and it defined the presets for the design and production of the trim part for which our material was to be used.
Since the application is firmly attached to the carrier, it cannot move, and its dimensional stability must match that of the frame. The trim must not be allowed to shrink or warp. Therefore, the substrate must provide greater heat resistance than the mineral-filled ABS material originally intended for use.
Many benefits and ready for immediate use
PULSE™ XT7215 has proved in many applications that it enables small gaps and a tight fit and finish for exterior applications thanks to its very low CLTE (35 mm/mm °C). It offers high ductility and easy flow allowing for greater design freedom, optimized wall thickness, and better economics. It can be processed even on smaller machines and allows improved cycles times to be achieved. Additionally, it facilitates the fabrication of lighter parts and the optimization of costs because of significant density advantage (density of PULSE™ XT7215: 1.25 g/cc).
BMW's supplier ordered a PULSE™ XT7215 material sample and invited us to deliver a presentation about the Trinseo exterior grades portfolio and the case study about the roof rails for the Opel Astra Sports Tourer. Following this we sent another batch for further tests, which the material successfully passed. It was a supporting fact, that PULSE™ XT7215 was already approved and listed at BMW (BMW standard GS93016). Our material not only met all the key requirements, it could also be used immediately without cost-relevant delays.
Contact Sr. Application Development Specialist at email@example.com for more details.