New developments in fast 3D-surface quality control

Inspection is the process of determining if a product deviates from a given set of specifications. Fast inspection usually involves measurement of specific part features such as assembly integrity, geometric dimensions and surface finish. It is a quality control task, but is distinguished from testing tasks. The visual inspection of 3D parts (car body parts) is a special task within manufacturing that has been automated at a comparatively slow pace up to this time. Different optical methods, applied for 3D measuring at microscopic and macroscopic levels of sheet metal parts, based on the projected fringes method (PFM), electronic speckle interferometry (ESPI), the structured-lighting reflection technique (SLRT), white-light interferometry (WLI) and also SEM-, AFM- and laser scanning methods (LSM) will be discussed. In addition, stylus instruments and also colorimeter measurements are included. The presentation closes with the advantages and disadvantages of different contemporary intelligent methods for car body inspections: neural net based classification, fractal analysis and wavelet transformation.