EXPERIMENTAL-STUDY ON PHYSICAL-PROPERTIES OF COMPRESSION MOLDED SMC PARTS UNDER PLANE-STRAIN CONDITION

The rheological property of SMC (sheet molding compound) and the effec t of molding variables on the mechanical properties of compression mol ded SMC parts under plane strain conditions were examined in this pape r. Simple compression tests using grease oil and mylar sheet as a lubr icant at various temperatures were carried out in order to characteriz e the combined effect of SMC resin, fiber, and temperature on flow res istance of SMC. To investigate the effect of molding parameters on ten sile and flexural properties of the molded parts, two different mold t emperatures and mold closing speeds were used for fabrication of the t est specimens under the plane strain compression molding condition. Fo r this purpose, tensile and three point bending tests were used. Surfa ce roughness was measured by the stylus type tester and examined. In a ddition, the effect of molding conditions and mold geometry on fiber o rientation and distribution in the molded parts was also investigated by taking the photographs of the burnt flat specimen and by SEM (scann ing electron microscopy) of a cross-sectional area of the part with a rib. The experimental results will be useful in designing new SMC form ulations and understanding material flow during compression molding of SMC in molds with or without a rib. Copyright (C) 1996 Elsevier Scien ce Ltd.