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A couple of years ago, GE Aviation (Evendale, OH) approached KRC Machine Tool Services (Independence, KY) to build two BlueArc machines. The machines are named after the environmental nature of the process as well as the color the electrode glows as it removes metal from the Inconel solid to create a blisk (bladed disk).
The fact that GE has come to your door and invited you to bid on a couple of roughing machines with a cost of about a million dollars apiece means something, especially because the machines use a process similar to ECM or EDM, but not really either, more like a combination of the two, an ECDM machine.
In this case, GE had already done its research, had worked with KRC many times before, and knew it was competent enough do the job (the upside). Because GE Aviation owns the IP (Intellectual Property), they also know that the winning bidder would have to play by their rules, which some companies consider just too great of a downside.
"KRC has worked on many projects together with GE over our 12+ years of doing business, and, in that time, we have developed a very good working relationship," says Scott Ashworth, KRC president. "What we didn't expect was a trip to China to see the GE research center where one of the prototype blisk machines would be running tests," says Ashworth.
"You couldn't actually see material removal because everything was taking place submerged," Ashworth says. "I later found out that submerging the process isn't for connectivity. In fact, the part can be machined dry. It's primarily to maintain consistent heat in the heataffected zone. Plus, it helps with smoke by dampening it into the liquid. Further, as the process is noisy, the liquid helps dampen noise. But it was amazing to see the speed at which they were roughing the part out of Inconel. It was very fast, about 40 ipm [1 m/min]."
ECDM process basically uses a copper electrode, 7 mm in diam, and then a variable power supply that can control the voltage from 0 to 70 V and the current from 0 to 500 A. What made this process interesting, because EDM, ECM, or even ECDM aren't new or novel was the...