Determination of Tolerance Regions for Assessment and Quality Control Parameters of Automotive Appearance

In the present study, attempts were made to investigate the possibility of developing a two dimensional appearance chart to make provisions for a straightforward assessment and control of appearance quality of achromatic automotive finishes. To this end, four series of random test samples in which the three geometric appearance attributes, namely specular gloss, distinctness of image and orange peel varied simultaneously were prepared using metallic black, metallic grey, metallic silver and solid white automotive finishes. The samples were visually evaluated by a panel of 16 observers, utilizing grey scale technique. Analyzing the results of correlation between visually quantified total appearance and instrumentally measured specular gloss, distinctness of image and orange peel attributes of random samples showed that there is a good correlation between instrumentally measured distinctness of image and the Wave scan Wd parameters, and the corresponding visually evaluated data at the four investigated achromatic levels.Using these two parameters, a two dimensional appearance chart was developed for achromatic automotive finishes under investigation. Discrete acceptable, tolerable and unacceptable tolerance regions were determined for distinctness of image and Wd parameters, separately for horizontal and vertical automotive body parts, using the results of visual inspections of 6 expert auditors of the Iran Khodro car manufacturing company on 28 randomly selected car bodies with different achromatic levels.