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| Press Release Number: ECP200302122 | 12-Feb-03 |
New waterjet system offers depot many advantages |
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| By Joey Eubanks Lead Industrial Engineer Coating removal is a key step in the process of refurbishing many turbine engine parts. Thermal spray coatings must be stripped to the parent metal and re-applied before the parts are reinstalled. Traditional methods of coating removal - such as applying an acid solution bath, media blasting, and machining - tend to be slow and expensive and risk damage to parts. The installation of an Automated Waterjet Coating Removal System in the Engine Parts Repair Shop at the Naval Air Systems Command (NAVAIR) Depot Cherry Point last year has proven to be an economically superior choice for coating removal. In comparison to the conventional coating removal methods, the waterjet lowers costs by essentially eliminating damage that occurs to aircraft parts during rework, significantly reducing the labor costs and turnaround time required for stripping parts, and significantly reducing the amount of hazardous waste generated. Coatings are removed with the waterjet by a combination of erosion and fracture, leaving the base metal much like it was before the coating was applied. The waterjet will easily remove thick composite thermal barrier coatings and inorganic flame spray coatings that could not be removed with acid soaking or grit blasting. "Coating removal using the waterjet offers us many advantages," Jesse Garman, Materials Engineering Division Chemist, said. "Only the coating is removed, and no base metal is lost as in grit blasting, machining, and grinding. Parts that previously could not be machined or ground and had to be scrapped can now be stripped, re-coated, and re-used. Part geometry is irrelevant, and turnaround time is dramatically improved from weeks to same-day service, if needed. Hot parts can be dropped off, stripped, and recoated in the same day. And since stripping and coating are performed in the same shop, there's no parts routing." In most cases, the waterjet has drastically reduced the turnaround time needed to strip parts. Parts that previously required hours or even days to be stripped in nitric acid dip tanks may now be stripped via the waterjet in a matter of minutes. "For example, it used to take a week to strip a T64 Compressor Case in an immersion tank," Garman said. "Now, the task can be accomplished in just 12 minutes." Reduction of hazardous waste is another way the waterjet generates cost savings. Most chemical strippers are costly to procure and dispose of and can be hazardous to use. Abrasive media stripping systems create solid waste that requires costly disposal procedures. The waterjet was procured from Progressive Technologies of Grand Rapids, Mich., at a cost of $962,695. It consists of a water purification system, two intensifier pumps each capable of delivering 55,000 psi of water, a seven axis gantry-mounted robot inside an acoustic enclosure, operational software, and a controller. Ultra high-pressure water is directed on thermal spray coatings by the robot through a rotating nozzle. "The projected payback period for this equipment is expected to be about 1.3 years," Garman said. NAVAIR Depot Cherry Point provides maintenance, engineering, and logistics support on a variety of aircraft, engines, and components for all branches of the U.S. armed forces. Employing almost 4,000 people, the depot is the only source of repair within the continental United States for many jet and rotary wing engines. It is the Navy's center of excellence for rotary wing aircraft, providing engineering and logistics support for all Navy helicopters. NAVAIR provides advanced warfare technology through the efforts of a seamless, integrated, worldwide network of aviation technology experts. From professional training to carrier launch, sensor data to precision targeting, aircraft and weapons development to successful deployment, and real-time communication to aircraft recovery, NAVAIR provides dominant combat effects and matchless capabilities to the American warfighter. Members of the depot's Waterjet Coating Removal System Acquisition Team are Joey Eubanks, Project Manager; Jimmy Amspacher, Mechanical Engineering Technician; James Walker, Electronics Technician; Jim Willis, Industrial Engineering Technician; Jesse Garman, Chemist; and Engine Parts Repair Shop Supervisor Richard Tomasik. Photo: At the waterjet operator console in the Engine Parts Repair Shop, Metalizing Equipment Operator George Cloud and Chemist Jesse Garman prepare to operate the system. (Photo by Joey Eubanks) |
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