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Detecting subtle cosmetic defects in automotive skin panels

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Hazra, S. (Sumit), Williams, D. K. (David K.), Roy, Rajat and Aylmore, R.. (2008) Detecting subtle cosmetic defects in automotive skin panels. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Volume 222 (Number 11). pp. 2203-2207. ISSN 0954-4062

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Abstract

Cosmetic defects, such as 'hollows', are deviations in topology of automotive skin panels that form as a result of springback at the end of the forming process. These deviations are usually too small and local to be detected by discrete measurements of the panel but become visually apparent after the application of paint. As a result, the perceived quality of a panel may become unacceptable and considerable time may be dedicated to minimizing their occurrence through tool modifications. This paper proposes that there are three aspects to the problem. The first is the springback of the panel, the second is the optics of the painted panel, and the third is the ability of human sight to perceive a defect. In particular, it is argued that hollows cause optical distortions that inform the human eye of the presence of a defect. The paper then suggests that signal processing techniques, in particular the wavelet transform, provide a way to relate the geometry of a hollow to the resulting optical distortion. The transform was applied to two physical parts and the paper will discuss the effectiveness of the transform in locating and quantifying the relative severities of the defects that were present.

Item Type: Journal Article
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Science > WMG (Formerly the Warwick Manufacturing Group)
Library of Congress Subject Headings (LCSH): Surfaces (Technology) -- Defects, Wavelets (Mathematics), Optics
Journal or Publication Title: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
Publisher: Sage Publications Ltd.
ISSN: 0954-4062
Official Date: November 2008
Volume: Volume 222
Number: Number 11
Number of Pages: 5
Page Range: pp. 2203-2207
Identification Number: 10.1243/09544062JMES910
Status: Peer Reviewed
Publication Status: Published
Access rights to Published version: Restricted or Subscription Access
Funder: Advantage West Midlands (AWM)
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URI: http://wrap.warwick.ac.uk/id/eprint/28890

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