Advanced techniques of on-machine cutter/part measurement and supplementary machining of out-of-tolerance features for accurate and efficient machining of 3-D printed complex workpieces

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Industry 4.0 includes intelligent manufacturing, and on-machine measurement is a kennel technology of intelligent manufacturing. In machining, tool size and wear are measured with a tool setter on a CNC machining center, and then the CNC controller automatically compensates the tool wear in the following machining; consequently, the worn tool cuts the part features without larger error. A machined feature is measured with a touch trigger probe on the machine after it is cut; and then if the feature is out-of-tolerance, supplementary machining is automatically carried out on the same machine. Therefore, on-machine measurement can increase machining accuracy and efficiency and reduce scraped parts. 3-D printed complex workpieces have to be machined to tolerance before use. Supplementary machining of out-of-tolerance part surfaces is crucial to 3-D printed workpiece machining. However, there are many problems with on-machine measurement and 3-D printed part machining. To address the problems, this research program is aimed at developing advanced key techniques. The research objectives include: to establish precise and completed models of measuring tools using laser and contact tool setters in terms of the tool setter structure, the CNC controller, the tool runout and geometry, the spindle speed and the tool feed rate, and then minimize the measuring time and maximize the measuring accuracy; to establish an accurate mechanistic model of measuring complex surfaces using touch trigger probe in terms of the probe structure, the CNC controller, the probe offset, the surface geometry and the probe feed rate, and then minimize the measuring time and maximize the measuring accuracy; and to propose an iterative approach to measuring points on the 3-D printed workpieces, automatically identifying and defining the out-of-tolerance regions and then generating CNC tool paths to machine these regions. This proposed research will contribute new scientific knowledge of on-machine tool and part measurement and lay a solid foundation for on-machine measurement research. It will substantially advance the techniques of on-machine measurement and 3-D printed complex part machining. This research will promote intelligent manufacturing and the additive manufacturing. It will train high qualified personnel and disseminate the new scientific knowledge. The techniques developed in this work will benefit the Canadian manufacturing industry through improving accuracy and efficiency of CNC machining; fortunately, the improvement is urgently needed to increase our industrial competitiveness in view of on-going globalization. This research is complementary to the past NSERC-sponsored projects of CNC machining and its results will be promptly applied to industrial production through our collaboration with Pratt & Whitney Canada, Bombardier, and some automobile companies.