In-Situ Measurement of Plasma Deposition Coating Thickness

A significant problem in precision manufacturing of large parts/assemblies is the requirement to make measurements over the surfacesof these parts for a variety of reasons including inspection/quality control; control of surfacing operations such as coatings, abrasive erosion, buffing, and texturing; and generation of "as built" documentation. A specific instance of this class of problem has been chosen; the exhause assembly for the engine on the F-22 aircraft. In this application the extent of the surface of concern is several square meters. A coating is being applied tothe surface, with a requirement to precisely control the coating thickness over the entire surface. Measurement precisions on the order of a fraction of a mil are required over the entire surface, with in-situ measurement being highly desirable so that the coating deposition process can be controlled to meet the coating thickness specifications. Current measurement technologies are inadequate to perform these measurements while the part is on the fixture, resulting in a very costly "trial and error" approach that must be addressed before the engine goes into production. One of the principal efforts of this proposal will apply the NGC concepts, OSAGE tools, and laser stripe measurement processes developed under previous reseach efforts, to this problem. The result of successful performance on this application will be a class of tools for precision measurement of extended, complex surfaces with a working prototype to be developed in Phase II, sufficiently general to be applied to a large number of manufacturing problems. Anticipated Benefits: As a result of this effort, significant cost savings will be realized by the US Air Force in the procurement of aircraft engines incorporating plasma-deposited coatings. The potential savings of this development alone is expected to be in the millions of dollars. The methods and tools to be developed have wide application in surface mapping measurements for military and commercial manufacturing.