RELIUS, part of BASF’s Coatings Division, is supplying a masking paint that shaves millimeters off Airbus parts. The paint hardens quickly and protects the aluminum substrates as the parts are dipped in sodium hydroxide solution. Thus, weight is reduced only on the surfaces that have not been coated with the special paint.

RELIUS, part of BASF’s Coatings Division, is supplying a masking paint that shaves millimeters off Airbus parts.

Up in the stratosphere, every pound counts. The large aluminum parts used in aircraft construction, which are thin to begin with, are generally slimmed down through etching with chemical solutions. In order to ensure that only the desired spots are chemically “milled,” the experts at RELIUS have developed a solvent-free two-component masking paint for the Airbus plant in the northern German city of Nordenham. The paint also hardens quickly. It protects the aluminum substrates as the parts are dipped in sodium hydroxide solution. Thus, weight is reduced only on the surfaces that have not been coated with the special paint.

The two-component masking paint is applied prior to the chemical milling process. A spray unit is used to completely coat the airplane parts with masking paint. After 30 minutes of drying time, a computer-operated laser cuts the dried coating following a pre-determined geometric pattern. The cut edges of the groove serve as a natural seal, eliminating complicated sealing work. The paint on the laser-cut spots can be stripped off easily by hand.

The entire part is then dipped in a sodium hydroxide solution. The uncoated areas are etched by the solution and thinned down precisely to the millimeter. With this method, the aluminum is reduced from a starting thickness of six millimeters to a mere two millimeters. All other areas are safely protected with the two-component masking paint, retaining their original thickness. Once the chemical milling process has been completed, the masking paint is removed from the part completely. The stripped paint does not have to be disposed of separately as special waste.

In addition to gaining weight reduction benefits, the Airbus plant in Nordenham has been able to completely shut down its solvent recovery unit.

The masking paint consists of two components: base paint and hardener. They are delivered separately and are mixed in a special two-component spray unit just before application. The new paint requires just one coat, as opposed to the two or three coats needed when conventional masking paints are used. The short hardening time of 12 to 13 seconds means that vertical and round components can also be coated easily. After a total drying time of just 30 minutes, the next step in the production process can be started. This innovation saves valuable time – taking just a fraction of the four hours that used to be required.

The Airbus plant in Nordenham is using the innovative product on the fuselage of the A380, the world’s largest commercial airliner.

For more information, visitwww.basf-coatings.com.