On the Cutting Edge -- Waterjet Cutting Tools
From fuselages and wings, to the fenders of a Chevrolet Corvette, to armor panels on military vehicles, composite materials are showing up with greater frequency in a wide range of applications.
But cutting and trimming composites is no easy task. The material is susceptible to oxidation and degradation from excessive heat. Carbon fibers don't cut well because they fracture instead of shearing smoothly.
It is largely for this reason that waterjet cutting is emerging as one of the fastest growing machine tool segments today. Having grown more accurate as a technology and offering non-contact cutting, waterjet has spread from aerospace and defense into job shops, electronics and the stone and tile industry.
"The biggest benefit waterjet has, regardless of whatever it's cutting, is that it's a non-contact cutting method with the absence of heat," says Dick LeBlanc, executive vice president at waterjet technology manufacturer Flow International. "You can machine thin to very thick metals with an abrasive waterjet and there are no metallurgical changes to the material. It's a cold-cutting process."
Abrasive waterjet cutting refers to a method of using water pressurized up to 94,000 pounds per square inch with a garnet abrasive entrained in the jet stream. The water is forced through a precision orifice up to 0.0015 inches in diameter. The water and abrasive garnet -- think of the material used on sandpaper -- cut materials with surprising speed, hitting accuracies of up to 0.001 inches.
Abrasive waterjet cutting, uses water pressurized as high as 94,000 pounds per square inch with a garnet abrasive entrained in the jet stream.
When waterjet cutting first emerged commercially around 1985, its early embracers came from the defense and commercial aircraft industries.
"Defense was the first area of heavy use for not just composites, but they started looking for alternative methods for cutting exotic metals, such as titanium, nickels, and various alloys," says Wysuph.
Today, the two biggest changes in waterjet technology are the increased reliability and a reduction in operating costs per hour. Companies such as Flow International, Mitsubishi, Jet Edge and Omax have released high- and low-end models aimed at specific industries.
"For contract job cutting, the most versatile cutting tool is an abrasive waterjet because it can cut thin metal, foam, glass, granite, thick materials, soft materials, hard materials and composite materials," says LeBlanc. "It's unlimited."
In an effort to merge the best of two technologies, several waterjet manufacturers, such as Sodick and Flow International, have created hybrid machines that combine wire EDM and waterjet cutting. Wire EDM provides unmatched precision, yet lacks the speed of a waterjet. The hybrid machine includes both a wire EDM head and a waterjet head, both of which move in and out of the work zone when needed.
The problem with hybrid waterjet machines is the combining of two processes that require two very different forms of maintenance.
Because composite materials are susceptible to oxidation and degradation from excessive heat, waterjet cutting has increasingly become the preferred machining method due to its cold-cutting process.
As waterjets have moved into cutting exotic materials, such as titanium, Inconel, Hastelloy and even glass, Flow International's LeBlanc says versatility is helping waterjets to become a preferred tool for cutting.
"The beauty of a waterjet is it wants to go through whatever is below it," says LeBlanc. "And it can cover a lot of ground quickly -- and with precision."
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