MULTIPLE QUALITY CRITERIA OPTIMIZATION IN REACTIVE IN-MOLD COATING WITH A DATA ENVELOPMENT ANALYSIS APPROACH II: A CASE WITH MORE THAN THREE PERFORMANCE MEASURES

Sheet Molding Compound (SMC) is a widely utilized material to manufacture automotive exterior body panels. Compression molded SMC parts are often coated with the objective to provide additional surface properties, provide environmental protection, and/or enhance aesthetics. One of the most rapidly increasing coating methods is called In-Mold Coating (IMC) in which a liquid thermoset is injected onto the surface of the cured SMC part while this is still in the mold. Cycle time, dimensional consistency, and surface finish are among the most important performance measures (PMs) to consider in the production of SMC due to their impact in profit and quality, hence these measures are also important when using IMC. Frequently, the PMs exhibit conflicting behavior i.e. lowering the cycle time might imply decreasing the part surface quality and/or achieving a lower overall part dimensional consistency. For this reason, one must exercise especial care to identify the best compromises between the PMs along with the processing conditions that result in these best compromises. The task of finding the best compromises poses a multiple criteria optimization problem. This paper describes an application of IMC to SMC where the multiple criteria optimization problem is addressed with a non-parametric approach known as Data Envelopment Analysis (DEA). The use of a graphical approach to identify the best compromises is not possible in the case presented here because four PMs have been included. This fact makes the use of the proposed approach completely necessary to solve the problem at hand.