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An In-line Surface Inspection System that Evaluates Projected Fringes using Spatial Phase Shifting Technique
Presented by: Optimal Inc. & Steinbichler Optotechnik GmbH
2004 World Congress for Non-destructive Testing (NDT) Montreal, CA, March 2004.
Session title: Optical Techniques
Topic: AN IN-LINE SURFACE INSPECTION SYSTEM THAT EVALUATES PROJECTED FRINGES USING SPATIAL PHASE SHIFTING TECHNIQUE
Session date: Thursday, September 02, 2004
Session time: 08:30 to 09:30
Presentation time: from 09:10:00 to 09:30:00
ABSTRACT
Methods available today to detect surface distortions and imperfections for automotive sheet metal panels consists of destructive methods like stoning or time-consuming inspection methods that involve extensive surface preparation and set-up like green rooms, fluorescent lights etc. These traditional inspection techniques give highly subjective information (depending on the inspector or the inspection device/method used) that result in numerous defects remaining undetected until after painting the panels. Additionally, the sample size of these inspections is very small and consequently useful statistical data non-existent. The resulting re-work and scrap not only adds costs in terms of material and labor but affects time and quality.
The use of fringe projection and spatial phase shifting to evaluate these projected fringes provides a method to detect defects on unpainted sheet metal quickly, while providing quantitative dimensions of the defect (depth, breadth, length and shape). The Automatic Body Inspection System (ABIS) is a non-contact optical device that was designed to be an in-line system providing 100% inspection. The technology enables the detection of defects greater than 10 microns (0.01mm) with a data acquisition time of less than a few milliseconds. ABIS is trainable and collects the knowledge of experienced quality testers and translates it into objective judgement criteria. It’s insensitivity to vibrations and has facilitated in-line integration and the automation of functionalities of measuring, identification, classification and marking of surface defects. |
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