Rigid microcellular polyurethane integral-skin foams produced with the RIM process are making inroads into larger parts than ever before.

Rigid microcellular polyurethane integral-skin foams produced with the RIM process are making inroads into larger parts than ever before. One recent example is the 72.7-lb tailgate of the 2007 Jaguar fi eld chopper tractor produced by Germany's Claas Selbstfahrende Erntemachinen GmbH. It was molded in a single shot by Pestel PUR-Kunstofftechnik, using the fl ame-retardant Baydur 110 microcellular formulation from Bayer MaterialScience (U.S. offi ce in Pittsburgh). The part measures 6.9 x 4.6 ft and contains a considerable number of undercuts and ribs. According to Bayer, producing this large, complex part would not have been possible using other technologies. Pestel uses sophisticated molds with multiple splits or split-ejector combinations. The aluminum RIM molds cost about 30% less than steel versions. Baydur 110's low viscosity is said to ensure fi lling of remote corners of the mold, even at pressures as low as around 145 psi. Metal connectors and other inserts can be molded in at the same time. Says Pestel managing director Ulf-Peter Pestel, "It is becoming increasingly important to combine as many functions and modules as possible into a single molding to ensure the most cost-effective production. The freedom of design in polyurethanes makes it possible to produce structures in a single shot without costly secondary fi nishing, even with undercuts, ribs, and big differences in wall thickness. The advantages of polyurethane over materials such as glass-reinforced SMC become particularly apparent in large moldings with a highly structured inner surface." Tel: (800) 662-2927 . www. bayermaterialsciencenafta.com

Bayer MaterialScience
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