In-process control of machining. Phase 1: Milling

A system to control the path of a milling cutter was developed, integrated with a machining center, and demonstrated. Feedback control was based on measurements of machined edge coordinates taken behind the cutter. The demonstration consisted of milling four, parallel, identical, teardrop-shaped openings, spaced 90 degrees apart through the wall of an orifice tube. A linear diode array, sensitive to reflected light, was used to locate and record the edge profile of each opening. Real-time tool path redirection was based on a continual analysis of generated orifice area accumulation, thereby basing control of the machining process on area, the parameter which best reflected the function of the part. After the machining was completed, the optical edge sensor was used to inspect the part before it was removed from the machine. These processes resulted in significant improvements in productivity and quality.