Search Results

Reinforced reaction injection molding (RRIM) has re-emerged as an important method in automotive exterior applications. Presently composite applications demand higher productivity and improved part performance. Stability at higher heat to endure E-coat oven bake, improvements in fillers yielding easier processing at high loading, improved toughness at high modulus, and higher productivity have already been realized with RRIM in Europe and NAFTA. Now the kinetics of one new material, Bayflex 190 is such that reaction is essentially complete at demold. In the past RRIM molded parts were required to be baked at 120°C and above to complete chemical reactions, attain complete physical properties, and de-gas parts prior to painting. In current E-coat applications postcure of 190°C is typical. Elimination of postcure means significant savings in energy, increased productivity, decreased handling and lower capital expense. Bayflex 190 polyurea attains virtually all properties at demold.

New thermoset polyurethane polymers for automotive body panels can replace steel, SMC, and thermoplastics. These new materials offer short cycle times, thin wallstock, high temperature post mold processing, excellent durability, and new levels of productivity. Two new materials have been developed. One is a high-performance polyurea system that allows for oven bakes up to one hour at 190°C. The other is a high performance polyurethane developed for thin wallstock applications that has established new levels of productivity in the manufacture of rocker panels, fascia, and side moldings in Europe. The quality of these polymers is such that high productivity via robotic demold and trimming has been demonstrated. The durability of both these products is evident from the point of demold when the part exhibits an unprecedented toughness. Tight parameter control via a computer-based Expert System®1 improves cycle times, monitors manufacturing, and reduces scrap.

Reaction Injection Molded (RIM) Polyurethanes are well-suited to automotive fascia applications. Their excellent impact resistance, paintability, and styling capabilities are well known. Efforts are underway in the automotive industry to improve the production economics associated with manufacturing RIM fascias. One method of reducing fascia material costs is to reduce the density of the polymer. This paper describes new experimental RIM systems that can be molded at a reduced density, yet still pass current OEM requirements, including on-car impact tests. These experimental RIM systems combine new filler technology and new resin formulations. The material cost for this system is competitive (based on molded part cost) with all other current methods of manufacturing fascias.

The use of low density urethane foam composites in automotive interior trim is an established technology. In existing applications such as door trim panels, increasing production volumes are providing the impetus for process modifications and improved formulations. In emerging applications such as instrument panel covers new performance requirements must be met. The development of new Baydur STR/F formulations to address these needs are discussed.

Improvements in fuel economy and lower vehicle assembly costs have contributed to the variety of new materials used for composite parts fabrication. Distinguished among these are materials known as Structural RIM (SRIM). The focus of this paper is on the development of internal mold release technology specifically in relation to the preparation of SRIM composite parts.

The basics of Structural RIM processing for high volume applications are discussed, and several developments which impact the costs and efficiency of this process are described. These developments include flow characterization and modelling, glass handling techniques and venting techniques and systems containing internal mold release.

An historical overview of the use of composites in the automotive industry is given with emphasis given to the advantages and limitations of particular processes for various applications. Structural RIM is described as a process which combines high productivity with controlled, predictable part properties. After the materials are briefly described, some new studies which investigate what is actually occurring in the mold during the Structural RIM process are discussed. Some early results of these studies are analyzed and areas of future study with the tools of this investigation are outlined.