Inspection of free-form shaped parts

Free-form surface inspection requires the measurement surface and the corresponding design model in a common coordinate system so that comparison between the two surfaces can be made. In practical engineering applications, the free-form shaped parts are sometimes assigned profile tolerance with or without the reference of design datum(s) based on consideration of assembly, functionality and other manufacturing requirements. This paper discusses the profile verification techniques for free-form surface inspection with and without datums. The inspection of free-from surfaces includes two major processes: (1) the localization of measurement data to design coordinate system based on the datum reference information or a number of extracted surface features; and (2) the further localization based on the surface characteristics so that the deviation of the measured surface from the design model is minimized. Implementation and tests of inspection samples have been carried out to verify the developed inspection techniques.