All-polypropylene body panels result in reduced weight and greater fuel economy

18-Mar-09

For the first time Ford in Europe has used an advanced polyolefin in a body panel application. The 30% talc-filled resin, specially tailored for the application, was selected due to its ability to deliver significant cost and weight savings with respect to steel and engineering plastics. LyondellBasell Industries' Hifax TRC 280X compounded polypropylene (PP) resin is being used to produce the tailgate outer panel and the roof spoiler for the Kuga, Ford's new crossover model. Taking into consideration the structural parts of the tailgate, a weight savings of around 30% was achieved as compared to traditional solutions made out of steel. Reduced weight translates into greater fuel economy and lower CO2 emissions. With only 169 g/km, the Kuga has the lowest-in-class-CO2 emissions. The material meets Ford's stringent specifications in terms of low thermal expansion and high stiffness. Given the close integration with the rest of the steel bodywork, the thermal expansion was an important metric for Ford designers. With just 4.5x10-5 mm/mm/°C, the resin's coefficient of linear thermal expansion (CLTE) is far lower than that of a standard PP resin and of many engineering thermoplastics. Compared to competitive standard PP resins, the Hifax PP compound offer stiffness of approximately 3000 MPa, whereas standard PP resins commonly used for exterior typically average 1500MPa. Both highly visible parts must display a flawless surface quality for painting. LyondellBasell's experts managed to develop a material enabling the manufacturer to produce parts with an extremely good surface quality, due to the resins outstanding melt-flow characteristics of 18 g/10 min. Mold flow analysis carried out by our CAE centre helped to further optimize mold design and gating.