Cutting Titanium Like a Hot Knife Through Butter

Blue Arc at work (Part 1).

The intense heat generated when machining high-strength metals like titanium can deform, chip and break ordinary cutting tools. As a result, the cost and cycle time for machining parts made from sophisticated alloys are both increasing as materials improve.

Blue Arc at work (Part 2).

General Electric (GE) uses these kinds of parts inside jet engines, gas turbines and other machines. “We needed a better tool for the job,” said Michael Petracci, president of GE Ventures Licensing. “Since there was nothing on the market, we invented one.”

Compressor blisk for the CF34 jet engine made from a single piece of metal. (Image courtesy of GE Global Research.)

Blue Arc is a thermal cutting process capable of slicing through aerospace-grade titanium alloy in three minutes—a job that normally takes 45 minutes. It uses a high-speed beam of electrons to erode and remove metal, eliminating the need for bit changes during shifts.

Compared to traditional machine tools, Blue Arc machining reduces the stress on aerospace blisks, compressor blades and other components. It is especially useful for machining large parts from a single piece of metal, which is the preferred technique for GE’s engineers since it retains the strength of the metal while minimizing the weight of the completed part.

Superalloy component before (left) and after (right) Blue Arc machining. (Image courtesy of GE Global Research.)

Several GE customers and businesses have used it to make parts from Inconel—an alloy used in jet engines—and titanium, which softens at 1,649 C. Since it doesn’t deform or break, it can cut machine tool capital costs by 30 percent and the cost of cutter tools by 70 percent.

GE estimates that it could save $200 million over five years using the technology.

According to Petracci, Blue Arc has a smaller footprint, wastes less material and generates less dust than traditional machining centers. It also doesn’t require the complete retooling of a factory to install. Instead, cutting machines can be retrofitted to work with the new technology.

A Blue Arc machine. (Image courtesy of GE Global Research.)

“Cutting tools have been around since the Stone Age and hard tungsten carbide tools, which have been around since the 1950s, have been their latest iteration until Blue Arc came along,” said Petracci.

GE partnered with Mitsui Seiki, a Japanese manufacturing-machine maker, to produce the prototype in 2011. It is now seeking licensing partners to test Blue Arc at GRC’s Detroit campus.

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