Mitsubishi Heavy Industries Technical Review
    Vol. 51 No. 3 (2014)   Machinery, Equipment & Infrastructure
    New Products

    Molding Technology to Realize Resinification of Automobile Parts

    Mitsubishi Heavy Industries
    Plastic Technology Co., Ltd.
    Sales Department

    In parallel with the development of eco-friendly cars such as hybrid vehicles and EV (electric vehicles), there has recently been a growing need for weight saving technologies to improve fuel efficiency in the automobile industry, with it contributing to environmental conservation and the establishment of a sustainable society. In addition, the simultaneous attainment of the improvement of market competitiveness is required, and as a result the fulfillment of cost reduction and flexible design, which are incompatible with weight saving, is an issue. A vehicle body consists of modules such as the front end module and the back door module, and exterior parts including a panorama roof. One effective vehicle weight saving method is resinification, but it has a problem with the fulfillment of the following requirements. (1) The front end carrier and back door inner require high rigidity and strength. (2) The back door outer and exterior parts have a decisive influence on the vehicle design, and therefore require forming flexibility, a surface shape that causes no defective coating and flexural rigidity. (3) Outer panels with a large projected area such as panorama roofs use injection compression molding that can be performed with lower clamping force because they require very high clamping force if normal injection molding is used. Injection compression molding has a problem with the occurrence of bias resin pressure in the mold, which causes unparallel mold parting line and results in an inaccurate thickness. Therefore an injection compression molding method that can maintain parallelism of mold parting line is required. To fulfill the above requirements, Mitsubishi Heavy Industries Plastic Technology Co., Ltd. Has developed the following three technologies. (1) Long fiber reinforced thermoplastics (LFT) plasticization technology that can ensure effective fiber length without breaking long fibers as much as possible for the resinification of parts requiring high rigidity and strength. (2) Highly dispersible, high kneading uniform melting technology that disperses the pigment master batch and talc master batch for the improvement of rigidity and reduction of linear expansion coefficient, prevents surface defects, has high formability and can perform high cycle molding. (3) Four-axis parallel injection compression molding that independently controls the positions of the four tie bar axes of a two-platen clamping device. This report presents the advantages and application examples of these technologies.