Investigation of a Plastic Component Interface Design & Assembly

Plastic underhood components often crack when fastened to mating components. The goal of this study is to determine what variables are most important with relation to this problem. To maximize the efficiency of testing, an L18 orthogonal array was used to structure the experiment. Experiments were conducted using a computer-controlled electric driven screwdriver and a manual torque wrench. Control factors were adjusted by using hardware as specified for each trial. The torque value at failure was recorded for all samples. The “larger the better” S/N equation was utilized for data analysis in this study. Optimizing the design and process was found to increase the S/N by 6.9dB when verified experimentally. Fastener washer thickness, joint fit-up, and screw setting speed contribute to the gain by 46%, 28%, and 27%, respectfully.