Experimental study on physical properties of compression molded SMC parts under plane strain condition

Abstract

The rheological property of SMC (sheet molding compound) and the effect of molding variables on the mechanical properties of compression molded SMC parts under plane strain conditions were examined in this paper. Simple compression tests using grease oil and mylar sheet as a lubricant at various temperatures were carried out in order to characterize the combined effect of SMC resin, fiber, and temperature on flow resistance of SMC. To investigate the effect of molding parameters on tensile and flexural properties of the molded parts, two different mold temperatures and mold closing speeds were used for fabrication of the test specimens under the plane strain compression molding condition. For this purpose, tensile and three point bending tests were used. Surface roughness was measured by the stylus type tester and examined. In addition, the effect of molding conditions and mold geometry on fiber orientation and distribution in the molded parts was also investigated by taking the photographs of the burnt flat specimen and by SEM (scanning electron microscopy) of a cross-sectional area of the part with a rib. The experimental results will be useful in designing new SMC formulations and understanding material flow during compression molding of SMC in molds with or without a rib. Copyright (C) 1996 Elsevier Science Ltd.