High-flow Long-Glass Fiber PP, an enabler for thin wall designs?

摘要

One of the primary focus areas for the automotive industry is weight reduction to increase fuel efficiency and reduce CO_2 emissions. In addition, there is an urgent need to expand the driving range in electro vehicles. Achieving both objectives is possible through the creative use of plastics and composites, replacing traditional materials. For less structural parts, such as Instrument Panel (IP)- carriers or door modules, weight-out is usually achieved by reducing wall thickness or mass density (using physical or chemical foaming with or without core-back technology). With current long-glass fiber reinforced polypropylene (LGFPP) material, combined with standard injection molding technology, a wall thickness of approximately 2 mm can be achieved in large IP- carrier parts. When advanced processing technology is used (injection compression molding in combination with core back foaming) a wall thickness of 0.8 mm has been achieved in an industrial air duct. In this study the potential of a generic high-flow LGFPP material to enable the manufacturing of thinner parts without the needs for advanced processing methods is investigated. A generic high-flow 20% LGFPP grade is chosen, and both the mechanical and rheological performances of this grade were compared to a standard grade (STAMAX 20YK270E). The potential for wall thickness reduction was investigated using a numerical Autodesk Mold-flow study in a generic IP-carrier model. The results indicate that with a generic high-flow LGFPP grade, wall thickness can be reduced to 1.5 mm i.e. 25% with respect to best-in -class commercial solutions, whilst maintaining the same pressure levels. Standard injection molding equipment can be used as well as standard simulation software for tool and gate layout, for optimal fill and warpage behavior. For the mechanical behavior, however, some reduction in material parameters has to be taken into account, due to different polymer composition and additional fiber breakage for wall thickness lower than 2 mm.