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Automated Optical Inspection for the Leather Industry

Cowhide Inspection

Automatic optical inspection (AOI) of natural marks on genuine leather is finally available to be used in production. In the past, the extremely varied appearance of natural marks combined with the difficulty of judging the resulting quality zones, made it impossible to use objective and reliable AOI in the leather industry. This has changed with a new machine vision solution by Dr. Schenk. The solution was recently successfully introduced in a German premium car manufacturer's production line.

Bild: Dr. Schenk GmbHBild: Dr. Schenk GmbH

Proprietary Dr. Schenk high-speed smart line scan cameras are combined with dedicated illumination units creating different optical configurations.

Bild: Dr. Schenk GmbHBild: Dr. Schenk GmbH
Figure 2 | MIDA (Multiple Defect Image Analysis) with four optical channels

Bild: Dr. Schenk GmbHBild: Dr. Schenk GmbH
Figure 3 | Comparison of manual marking with chalk vs. automated inspection

This makes it possible to highlight all characteristics relevant for detection and qualification of natural flaws in cowhides, which - given their endless variety and shapes - was challenging in the past. A single row of cameras acquires all images with Dr. Schenk's Multiple Image Defect Analysis (MIDA) technology. At the same time they are analyzing using sophisticated AI models. The first illumination unit enhances differences in color and gloss; the second illumination unit is more sensitive to the structure of the hide's surface; the third illumination unit makes even more structural details in the hide visible; it also allows analysis of features such as roughness and depth. This third illumination unit is aligned perpendicularly to the transport direction of the hide (CD), offering maximum sensitivity for detection of scars, wrinkles and folds oriented across the hide. When these three-dimensional, mostly elongated, natural flaws are aligned in transport direction (MD), the CD-configuration does not deliver optimum results. For this common scenario the Dr. Schenk oblique illumination is used and has been proven to make all natural flaws visible for further processing.

dr. schenk gmbh

Dieser Artikel erschien in inVISION E-Magazin inVISION International (english) 2023 - 18.10.23.
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