Automated Inspection of Polished Skin 2020-01-0032
This report is about development result of an automatic defect detector for polished skins. The “polished skin” material is used for an outside plate of commercial airplanes. The polished skin is manufactured by polishing the surface of an aluminum clad material and it has a uniform high level of color, brightness, and reflectivity. It can be used without painting because the surface has a natural oxide layer which prevents corrosion.
The polished skins are inspected with visual observation and it is large burden for inspectors to find minute defects on the large size materials. An automated inspection is not easy because the material has mirror surface and its size is large. Defects on the polished skin can be classified broadly into three categories: dent, bump and color change. Therefore, a defect detector has to be able to detect these defects, and measure surface profile of defects.
This technical report presents the outcomes from a design and a manufacture of the defect detector which has been designed to be low cost and high performance. It has multiple line sensor cameras, and a finding defect has been achieved by image processing. As a result of working on the formulation of the inspection method and the development of the large size apparatus, an inspection technology and an algorithm of the automatic inspection have been established. Defect detection performance of the developed apparatus is equal or higher than the current visual inspection. Furthermore, although the measurement time depends on a material size, it takes mostly five minutes or lower until a report is printed, which is much shorter than the visual inspection.
In conclusion, this technology could enable the automatic inspection of large size mirror surface materials which are currently inspected manually.