Tooling & Production - March/April 2009 - (Page 20) ECDM strategies Roughing it 5x faster Special process chips away Inconel blanks into aerospace blisks E Aviation of Evandale, OH, had a vision of a machine that would rough out blisks (bladed disks) from an Inconel blank — and that it would use a process combining Electro Chemical Machining (ECM) and Electrical Discharge Machining (EDM), called ECDM. It is now roughing material out five times faster, and the ECDM time is one-half as much as before. G research center, Scott Ashworth, president of KRC, and one of his partners saw a prototype version of a blisk machine. “You couldn’t actually see material removal because everything was taking place submerged,” Ashworth said. The submersion process was primarily to maintain consistent heat in the heat-affected zone, he said. In addition, it helps with smoke by dampening it into the liquid, and since the process is noisy, the liquid helps dampen noise. Constant arc crucial GE developed this new process to ECDM material — to “rough” it off. It takes a copper electrode, 7mm in diameter; a variable power supply to control voltage from 0 to 70 volts; and current from 0 to 500 amps. What makes this process unique is the switching power supply, a fast pulse power supply, and GE’s software that communicates between the control and the power supply. The real process is in monitoring the voltage, the current and the feed rate, and continually manipulating those to mainThe Blue Arc machine is named after the color the electrode glows as it removes metal. tain a constant arc, which is essential to precise material removal. KRC Machine Tool Services of Indepen“We originally thought about building our dence, KY, made it happen. The company own machine,” Ashworth said, “but we ended built two Blue Arc machines, named after the up talking to our friends at Mazak (Florence, color the electrode glows as it removes the KY). They agreed to sell us two-thirds of the tough metal at 40 ipm. machine, and we finished the rest. While on a trip to China to see the GE 20 tooling& production March/April 2009 www.ToolingAndProduction.com http://www.ToolingAndProduction.com
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