Precision Machining of Composite with Waterjets

Waterjets are widely used to cut and trim composites and techniques have been developed to trepan and pierce materials without causing delamination or fiber break-out on the exit side. However, using waterjets to mill countersunk holes has not been demonstrated before. This project will use a patented waterjet milling process to show that waterjets can successfully mill countersunk holes in composite materials for airframe structures without damaging the material. The proposed process is robust, reliable, inexpensive and very flexible, cutting holes from as small as 0.060 to inches in diameter, without the risk of heat damage to the material. The process is projected to be much faster than mechanical cutting tool methods and the nozzle wear life is in excess of 70,000 holes. Waterjet equipment already at the Fleet Readiness Centers could be used to cut stand-alone parts and tooling can be developed to drill holes in-situ on aircraft. In addition to carbon fiber products, the process can also be used to cut glass and aramid fiber reinforced product and even cut laminated titanium-graphite materials. The process works on inclined holes and laminated structures that include composites over metal framework.