The Influence of Interface Geometry on the Joint Strengths of Hot Plate Welded Composites

ABSTRACT: Interface geometry before joining has been an important factor for the welding quality of hot plate welding. In the present study, weld interfaces of six different geometries were studied, namely flat, triangular (308, 458, and 608), rectangular, and semi-circular interfaces. Three materials were used in the study: virgin polypropylene, and 20 and 30 % glass fiber-reinforced polypropylene composites. All specimens used in the experiments were molded using a pin injection gate on a reciprocating injection molding machine. After welding, the joint strength of the composites was determined by a tensile tester. Welded 20 % glass fiber-reinforced polymers were found to exhibit the highest joint strengths. For the parameters selected in the experiments, hot plate temperature, heating time, and geometry of weld interface were found to be the principal factors affecting the joint property of hot plate welded composites. In addition, the triangular and rectangular weld interfaces were found to weld parts of the highest strengths for virgin polypropylene and 20 % glass fiber-reinforced polypropylene composites, respectively, while the joint strengths of 30 % fiber-reinforced composites were improved by adopting non-flat weld interface geometries