ABRASIVE WATERJETS CUT THROUGH TOUGH MATERIALS

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D2 tool steel one inch thick is cut into blanks for another machinery manufacturer, who then mills the blanks into tolerance. The alternative process, precision casting, subjected the parts to stress. Metallurgical inconsistency from the process resulted in cracking and heat-affected areas. Admittedly, cost is higher per part using the waterjet method, but is made up by the increased yield.

In another application, hip stem blanks are cut from titanium one inch and thicker. The waterjet process reduces milling time by eliminating heat tempering and slag accumulation resulting from flame cutting. It also cuts the titanium five times faster than a bandsaw.

The process is also being used for strip-cutting stock material, which reduces production time, and conserves material because of the kerf width. Titanium-graphite laminates for the aerospace industry can be cut in complex patterns with small radius curves, holes and square corners. The process produces a clean, smooth edge with no delamination or heat distortion.

Creative Edge Corp. also applies the process to sandblasting masks for a sign manufacturer. The masks are cut out of 3/16-inch steel with an intricate design pattern. The waterjet-cutting process was chosen for its accuracy, reproducibility and elimination of secondary processes.

Other manufacturers have also turned to waterjet cutting when they needed to produce parts from difficult-to-machine materials. According to Frank Scharwat, OEM manager at Flow Systems Inc., Seattle, Wash., a manufacturer of waterjet pumps, a customer in California that produces parts for the aerospace industry found that "with conventional cutting tools, it took two and a half hours to cut a fuselage window opening in 0.0375-inch titanium. This time-consuming method was unacceptably expensive in terms of labor and cutting-tool costs.

Plasma arc or oxyfuel torches, for example, created heat-affected zones and metal distortion. As a result, components had to be cut to very rough tolerances, leaving as much as an inch of margin to be trimmed, shaped and deburred by hand." Using waterjet technology the job is finished in 25 minutes, with no finishing work required.