Rifling Gun Barrels with Waterjets

Refractory alloys such as tantalum-tungsten and ceramics are being pursued as a solution to high temperature erosive wear of gun barrels. However rifling of these materials with conventional broaching and electrochemical milling is proving to be difficult. This proposal seeks to demonstrate an innovative alternate grooving method, abrasive waterjet grooving. Waterjets are normally used to cut completely through materials but Ormond has developed a proprietary technique and software that uses waterjets to mill to a controlled depth. The process is being used to groove long channels in high temperature metals for scramjets, cooling channels in rocket nozzles, fluid channels in fuel cells and is even capable of milling grooves in silicon carbide and rhenium. This project will consist of designing and building a waterjet rifling machine to groove the 25 mm inside diameter of 2m+ long tubes and grooving of tantalum and silicon nitride. The baseline geometry will be the Bushmaster M-242. Cost projections indicate that this would be a very inexpensive approach and suitable for production operations. This project will demonstrate that the tolerances and surface finish required for rifling can be achieved economically with the new waterjet grooving process.