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Proceedings Paper

Paint skip detector
Author(s): Michael J. Haugh; David P. Stone; Mohan Thangavelu
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Paper Abstract

A method to automatically detect areas on coated aluminum sheet that were left uncoated due to a process malfunction has been developed. Detection sensitivity approaches a 1/4-inch diameter bare spot on the aluminum sheet moving up to 1,000 ft/mm The coated aluminum sheet exits a curing oven at temperatures near 410°F. At this point in the process, any bare spots on the aluminum sheet have an approximate emissivity of 0.10. The coating increases the emissivity by 0.15 to 0.75 depending on type and thickness. Since the bare sheet has a lower emissivity, a coating skip will produce a sudden drop in radiated energy (apparent temperature) . The magnitude of the drop depends upon the coating skip size, the coating thickness, the sensor spot size and the sensor response speed. A scanning thermal sensor and signal processor collects line scan information. A baseline following threshold is used to detect anomalous incidents. These incidents are tracked from scan to scan in order to define a complete defect. Paint skip size, severity and location (both downweb and crossweb) can be reported.

Paper Details

Date Published: 1 March 1990
PDF: 10 pages
Proc. SPIE 1313, Thermosense XII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, (1 March 1990); doi: 10.1117/12.21934
Show Author Affiliations
Michael J. Haugh, Kaiser Aluminum & Chemical Corp. (United States)
David P. Stone, Kaiser Aluminum & Chemical Corp. (United States)
Mohan Thangavelu, Kaiser Aluminum & Chemical Corp. (United States)

Published in SPIE Proceedings Vol. 1313:
Thermosense XII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications
Sharon A. Semanovich, Editor(s)

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