It delivers 55,000 psi of water pressure through a hole as narrow as 0.2 mm, and it can cut metals into complex shapes in just a fraction of the time required by traditional milling machines. And, as if true to its name, the Calypso WaterJet System acquired recently by Joachim Grenestedt, associate professor of mechanical engineering and mechanics, has livened things up in the department’s composite materials lab.

Ever on the lookout for new uses for lightweight composite materials, Grenestedt used the waterjet to cut a circular carbon-fiber skin for a unicycle wheel. Then, after visiting a local company that manufactures aluminum seat-belt harness trusses for sports car, he was inspired to use the waterjet cutter to fashion a carbon-fiber harness. He redesigned and manufactured a truss for a Porsche 911, and achieved a 30-percent reduction in weight with his harness, even while using the heavy original hardware from the aluminum harness.

A job that would take a day for a milling machine can be accomplished in 10 minutes using the waterjet cutter,Grenestedt says. The computer-driven machine, which works from CAD drawings and creates its own tool paths, offers other advantages.

“We do a lot of joining of stainless steel with composites,” says Grenestedt. “Other types of saws, diamond saws, for example, can be used to cut the composites, but the stainless steel clogs the diamond saws. The stainless steel can be cut with other types of saws, but these tend to destroy the composite and the all important steel-composite interface.”

The Calypso, Grenestedt says, gives the composites lab all the equipment needed to design and fabricate composite products. The lab also has composite production facilities, such as vacuum infusion and prepregs, and software capable of doing finite element analysis, structural optimization, and CAD-CAM. This array of tools enabled the lab to
produce the unicycle wheel cover in just seven hours, including two hours for design and analysis, one hour to make the carbon-fiber composites, one hour to generate the tool paths and cut the wheel, two hours to make the assembly fixture, and one hour for assembly.

Grenestedt is working on various carbon-fiber projects with Chris Wonderly, one of six mechanical engineering graduate students he advises.