APPLICATION OF TAGUCHIS-METHOD ON THE OPTIMAL PROCESS DESIGN OF AN INJECTION-MOLDED PC PBT AUTOMOBILE BUMPER/

The manufacturing process of an injection molded polycarbonate/poly(bu tylene terephthalate) automobile bumper was optimized, using Taguchi's method, to eliminate silver streaks on the surface of the product. Fi rst, a set of process factors was selected and a preliminary experimen t was conducted with an L-12 orthogonal array to screen the significan t factors, check the validity of the data fitting model, and predict a n improved process condition to overcome the filling difficulties. Sec ond, using the selected control factors, a principal experiment was co nducted with an L-18 orthogonal array to predict an optimal process co ndition that solve the quality problem. Finally, the predicted process condition was tested on an 2500-ton injection molding machine to conf irm the prediction. The results reveal that the main factors that dire ctly relate to the generation of silver streaks are the mold temperatu re, the fill time, the fill/postfill switch over control, and the inje ction rate. (C) 1998 Elsevier Science Ltd. All rights reserved.