Automatic Optical Inspection for Magnetic Particle Detection of Forging Defects
The magnetic particle inspection method is to detect the surface of the ferromagnetic material and the subsurface flaw. It can be considered as a combination of two nondestructive inspection methods which are magnetic flux leakage inspection and visual inspection. The visual inspection is performed by the quality control personnel under high-power ultraviolet light. Because of the strong ultraviolet light, this method has caused damage to the eyes of quality control personnel, and the detection results are prone to errors and cause missed inspections. Therefore, this study developed an automated detection system that can be used to replace manual visual inspection. This study uses a self-made aluminum alloy semi-circular tube type cover, diffused light source, high-resolution CMOS industrial cameras and image processing algorithms. The intensity of the ultraviolet light source used in this study was derived from the illumination of the semi-circular tube type light source cover. The best UV light source parameters were available when the bilateral light source was fully open, the light source illumination angle was at 120°, the light source intensity was at level 2, and the filter was used. The average value of the RGB values and the standard deviation of defects on work-piece were analyzed. Experimental results showed that the RGB average values were 38.66, 35.99, and 26.06, respectively, and the maximum standard deviation was G standard deviation of 86.83.
KeywordsMagnetic particle inspection Automatic optical inspection Ultraviolet light Defect detection
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