Investigating Primer Effects on Top Coat Structure : A Study Made at Volvo GTO, Umeå

Sammanfattning: Quality control is an integral part in all production industry. One important part of this control is the examination of the surface structure. This is especially important in automotive industries where the visual appearance is a big part of the general perception of quality for the customer. Structure defects and irregularities become even more apparent in trucks than in cars due to the large flat vertical surfaces being painted. In this thesis we explore the possibilities of modeling the relation between primer structure and top coat structure in truck cabs at Volvo Trucks, Umeå, Sweden. We also investigate how the painting parameters of the primer affect the structure of the top coat. The study regarding the structure is conducted on previously collected data (N=384). Due to the measurements not having been taken on the same specimen throughout all treatments in the process the cabs with primer measurements are matched to the top coat measurements based on proximity in production ID number. Significant models are found (P<0.001) and they perform marginally better than the null model in cross-validation. An experiment is designed to investigate the effects of primer painting parameters (paint flow, bell speed and oven temperature) on the top coat surface (N=20). The models constructed from the selected painting parameters were significant (P<0.001) with the best model having an R2 of 0.88. We conclude that in a lab setting we can use the painting parameters to predict the structure of the top coat. We make efforts to validate our study including measuring cabs in production. Results are discussed and we give suggestions for further investigation.