Development of a retention mechanism for minimizing defective overlap in film-insert molding

Film-insert injection molding is a relative new technique replacing for traditional post-molding decoration in order to cut down manufacturing cost and to avoid environmental pollution. In film insert molding, one of the most important considerations is how the inserted film is held in place in the mold tool for avoiding overlap phenomena. This paper presents a simple and effective mechanism that holds the inserted films in desired places during the injection process. The mechanism consists of adaptive retention pins with special designed shapes and appropriate spring force. The proposed method was applied to the chrome-plated film-insert molding process for an automotive radiator grill. The result shows that the defective rate caused by overlap phenomena reduces from about 20% to 3% when changing from electrostatic holding method to the new proposed design. The manufacturing cost of the radiator grill made by film injection molding method reduces 7.8 % compared to the one made by a traditional chrome-plating method.