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GE Pushes Out Blue Arc, Calling it ‘Big Step Forward’ in Cutting Tools

Brett Brune
By Brett Brune Editor in Chief, Smart Manufacturing

GE is preparing to sell to outsiders a subtractive manufacturing technology called Blue Arc that represents “a big step forward” in cutting tools, a field that’s been stuck on hard tungsten carbide tools since the 1950s, Dan Potvin, licensing manager with GE Ventures, said.

Andrew Trimmer, a chemical engineer at GE Global Research, has been developing cutting applications, improving the cutting performance for difficult to machine alloy and low rigidity materials, and developing process control for Blue Arc over the last 10 years. Here, he holds a Blue Arc cutting electrode.

Blue Arc, a high-speed electro erosion technology, is on display at the GE Global Research Automation Center in Van Buren Township, MI, and sales folks are headed to the trade shows IMTS in Chicago and JIMTOF in Tokyo in the next few weeks to sing its praises.

Blue Arc uses an electro-erosion process GE developed for internal use 15 years ago, representing “the fastest way to rough cut extremely tough alloys” like aerospace-grade titanium alloys and extremely tough nickel alloys, he said. “We’re using electrical energy to create sparks between the tool, which is an electrode, and the workpiece, which is another electrode.”

Blue Arc is about four to five times faster than conventional cutting in aerospace alloys, Potvin asserts. GE is currently not aware of any competition, other than conventional machining, for the technology that is commercially available, he added.

The newer materials are tough to machine. The level of heat generated during the machining of them can damage cutters that were established years ago. Making parts from the newer metals generally has been taking longer and costing more. GE needed to find a better way, because it uses parts of this ilk in gas turbines and jet engines.

Blue Arc is sort of a gentle giant. It touches the part it is machining, but there’s no real force.

It melts part of the workpiece away and quickly flushes away the molten material, “so it uses very low force, and that very low force allows you to do the higher speeds,” he said. “It also allows you to do unusual geometries, long extensions on the tool, flexible parts and so forth.”

The original process was developed as a submerged process. But the process no longer needs to take place under water. “Now we can actually do a conventional machining type application where you have just the flooded coolant coming onto the tool.

“The theory behind the process is that you bring tool and workpiece together, and they start sparking at a very high amperage, low-voltage, which is 25 to 30 V, and that sparking creates the heat that melts the workpiece.”

Once the right portion of the workpiece is strategically melted, “the next job is to remove that molten material as soon as possible,” he said. “That’s why we adopted this process—a very high pressure flushing system.”

The flushing happens in milliseconds.

GE has up to 1000 PSI pressure coming through the center of the tool, for one circuit. It has four circuits of coolant going on, and they are programmable from the CNC program. Different pressures can be adjusted for different applications.

Long tested in GE’s own manufacturing sites, the technology is ready for the open market, Potvin said. “We are actively looking for licensing partners/early adopters,” he said. GE sees Blue Arc as a licensable technology to third-party machine manufacturers.

GE partnered with Mitsui Seiki, the Japanese machine builder, to come up with a five-axis, horizontal machining center with a Blue Arc head attached, starting in 2011. It is built in Japan, and GE has on display in Michigan a prototype machine. The machine does not include the A axis.

The Blue Arc on display in Michigan has 4000 amps for its power supply and up to 30 V DC. It’s a hybrid machine: It can do conventional and nonconventional at the same workholding place.

If a manufacturer needed to do roughing because it wanted to remove a lot of material from a tough alloy, it could, say, take 95% of the material off of the block with which it started—and then take care of finishing without removing the workpiece. The machine in Michigan has onboard 120 tool cartridges in a magazine.

It does all this by simply removing the Blue Arc head – via a robot – and putting in its place a conventional, multiple-point cutting tool. The Machine on display in Michigan employs a FANUC robot, as well as a FANUC CNC 30-series as its “brain.”

The process is like reverse welding. “Instead of adding material, we are removing material through an arc process that melts material,” Potvin said.

Blue Arc can eliminate “a really big, high-powered machine and expensive cutting tools” and replace it with a machine that has a much smaller footprint, Potvin said. The overall machine footprint can be reduced by 20-50% compared to a conventional roughing machine that would have capability to remove material at the same rate of a Blue Arc enabled machine, he added. That is because Blue Arc’s low force means it does not need to be as rigid for higher material-removal rates.

Because it uses no- and low-force technology, it can be used for cutting unique geometries. Difficult to reach, deep cuts and very thin cuts are its forte.

GE expects it will sell well for aerospace, power generation and oil and gas applications. Automotive is another possible market.

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