Ytstruktur på lack : En praktisk jämförelse av mätverktyg

Sammanfattning: A big concern when painting surfaces is the unevenness of the surface texture that is created by the paint. This is a well known problem for the automotive industry, referred to as The Orange Peel Effect, creating a surface texture like that of an orange. This project aims to answer if the currently used Wave Scan could be replaced with the new Optimap to measure the Orange Peel Effect. A standardized measurement of this Orange Peel Effect are the N1 and N3 values, calculated through the BMW-Ford-scale and used by Volvo Trucks. In the first part of this report five models are created and evaluated to make the measurements from the new Optimap comparable with the currently used Wave Scan. In this report it is shown that N1 and N3 could be estimated such that hat(N1) = 2, 551813 + 0, 018900 ∗ Tb + 0, 089610 ∗ Td hat(N3) = 3, 862056 − 0, 014959 ∗ Tb + 0, 019958 ∗ Tc + 0, 067837 ∗ Td where Tb,Tc and Td are measurements from Optimap. By replacing Wave Scan with Optimap Volvo Trucks would be able to measure underlying layers like the matte base coat. Volvo suspects that the underlying layers could affect the top coats surface structure. If this is true it could then be further investigated and in turn optimized. This first part is modelled using measurements from plates which are painted with the truck cabs. These plates are measured with both tools and 110 paired measurements are used for the modelling. The variance is analyzed using another set of 24 plates with 6 replicates each, yielding 144 paired masurements. The two tools measures significantly differently for different wave lengths. Some of Optimaps measurements are also significantly different between the replicates of the same plate. The second part of this project is to evaluate the effect that the base coat has on the end product surface structure. Volvo Trucks is interested in the trends over time in the orange peel. This is done using data acquired from the production line, with truck cabs measured with base coat applied and cabs with top coat applied. Does the base coat follow the same trends? The result is that, due to lack of paired data, not enough evidence is found to either support nor reject the hypothesis that the base coat affects the end products surface texture. A significant difference between the different base coats is found. This is discussed and taken into account in the third part. The third part consists of a recommendation to Volvo Trucks on how to use the Optimap and further investigate the possible predictors of orange peel. This recommendation mainly focuses on reducing the number of variables. This could be done with only one type of top coat painted on the different base coats, using the same type of base surface for every measurement. The surface could then be measured before and after the top coat is applied to aquire paired data. This could be done in a laboratory in small-scale, and depending on the outcome more experiments could be constructed. In future studies one can investigate one of the base coats further. The same experiment could then be done with different alternations of one base coat instead of using several.