NAVAL AIR STATION NORTH ISLAND, Calif. –
Fleet Readiness Center Southwest’s (FRCSW) metal processing shops in Building 472 restore thousands of crucial metallic aircraft parts and components annually.
Many of the items have sustained damage or suffered prolonged exposure to the harsh environment of the Navy’s fleet.
Once inducted, components are stripped to their metallic structures through blasting and cleaning methods and inspected for indications of corrosion or unusual wear. About half undergo a non-destructive inspection (NDI) to determine the cause of defects found during visual inspections.
Following repairs, the components (if required) are plated and sent to the paint shop. Afterward, they are deemed ready-for-issue or sent to kitting for installation.
The shops are divided into four work centers: the blast shop, cleaning shop, plating and metal spray, and employ artisans from a variety of trades including sand blasters, robotic shop peening mechanics, electroplaters, robotic metal spray finishers and metal finishers.
The first step in the restoration process is the removal of any residue.
Blast media removes corrosion by using fine granules of glass, metal or ceramic. The media size used depends upon the amount of material removed and the composition of the part.
Shot peen, for example, is typically made of metal or plastic and varies in size to as small as a grain of sand. It is used on a variety of parts including landing gear, turbine disks, and aircraft wheels.
Blast shop facilities can accommodate large components like canopies and windscreens. During the process, media blast is vacuumed from the walk-in chamber and recycled, while smaller parts are treated in hand cabinets.
Afterward, components are sent to either NDI, the cleaning shop or to plating.
In the cleaning shop, aluminum and nickel-plated parts are immersed in a strip tank of alkaline solution. Steel-based parts are placed in a nitric acid strip tank, then rinsed in hot water and placed in a dryer.
To clean parts made of plastics and some metals that are not compatible with the acidic or alkaline-based solutions, the shop uses an aqueous degreaser. The degreaser removes oils, grease, metallic flakes and chemicals.
Steel and aluminum parts typically complete an NDI process before forwarding to the plating shop.
Once cleaned, most components move to the plating shop where nickel, chrome, silver, or cadmium are applied.
Cadmium is used for components exposed to a salt-water environment because it serves as a protective coating to the substrate materials.
Cadmium is usually electroplated to steel, copper, and powdered metals via an alkaline bath containing cadmium oxide. Once complete, depending on the material it is covering, the component is placed in an oven and baked for up to eight hours.
Ionic vapor deposition (IVD) applies aluminum, steel, brass, or beryllium to component substrates primarily for corrosion protection. The procedure may be operated in a vacuum to minimize potential contamination when aluminum coatings, for example, are applied.
The IVD process coats steel and copper alloy parts including bushings, springs and bolts. Larger parts needing plating to a small area undergo a stylus plating procedure where numerous coatings are applied to achieve the desired thickness.