In-Situ 3D Optical and Mechanical Metrology of Fabricated Parts

This project will develop on-machine (in-situ) metrology methods, standards, and performance metrics for inspecting and certifying high-value products while the fabricated part is still fixtured within the manufacturing equipment – with a focus on the growing importance of micro/meso-scale fabrication systems and products. Optical and mechanical metrology methods will be incorporated into manufacturing systems and evaluated for in-situ part certification and independent measurement of part features relevant to a variety of platforms and applications. The real-time product data obtained by the in-situ measurement systems will form the basis for future manufacturing process monitoring and control.

The holy grail in durable goods manufacturing is elimination of the need for off-line part inspection, typically performed using coordinate measuring machines (CMMs) and related inspection tools. U.S. manufacturers currently use off-line part measurement and certification for quality control of high-value products. Despite their high accuracy, CMM measurements are time-consuming and must be performed in specialized environments removed from the production floor, resulting in increased production times and higher manufacturing costs.

Research will focus on extending the application range and accuracy of 3D imaging systems in production environments, overcoming existing limitations due to line-of-sight requirements, surface imperfections, and variability in part reflectivity, lighting, shadowing, and color. A strong candidate for such optical in-situ measurement method is fringe projection.  Fringe projection, which is based on photogrammetry, answers many in-situ measurement challenges by providing long working distance to withstand harsh machining environment, flexible setup, large field of view and robust system with no moving parts.

The second focus of this project will be the development of a method for on-machine coordinate metrology assisted by metrology frames to reduce the uncertainty of dimensional measurements carried out on the production machines.  The metrology frame concept is very well suited for micro/meso-scale machine tools, which will be used as the testbeds for this project