In the course of a year, thousands of critical metallic aircraft parts undergo restoration through the metal processing shops aboard Fleet Readiness Center Southwest (FRCSW).
Many of the components have either sustained damage or suffered from exposure to the harsh environment of the Navy's fleet.
Once inducted, components are stripped to their metallic structure through blasting and cleaning methods so they may be inspected for signs of corrosion or unusual wear. About half undergo a non-destructive inspection (NDI) to investigate the cause of defects found during visual inspections.
Following any repairs, the components (if needed) are plated and sent to the paint shop. Afterward, they are deemed ready-for-issue or sent to kitting for installation.
Located in Building 472 the shop is divided into four work centers: the blast shop, cleaning shop, plating and metal spray, and employs 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 to remove any residue.
Blast media removes corrosion by using fine granules of glass, metal or ceramic. The media size varies depending 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.
The blast shop has five walk-in booths that can accommodate large components like canopies and windscreens. During the process, media blast is vacuumed from the walk-in chamber and recycled.
Smaller parts are treated in hand cabinets.
From the blast shop, components are sent to 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, while steel-based parts are placed in a nitric acid strip tank. Afterward, they are rinsed in hot water and placed in a dryer.
Steel and aluminum parts typically complete an NDI process before forwarding to the plating shop.
To clean parts like 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.
Once cleaned, many components move to the plating shop where nickel, chrome, silver, or cadmium are applied in the plating procedure.
Cadmium is suited for components exposed to a salt-water environment as 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. Afterward, 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 mostly for corrosion protection. The IVD may be operated in a vacuum to minimize potential contamination when aluminum coatings, for example, are applied.
The IVD procedure 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 brushed coatings are applied to achieve the desired thickness.