CO2 composite spray cleaning in aerospace manufacturing

Ensuring that a surface is clean prior to the application of paint, sealant or adhesive is critical for adequate adhesion. Reducing flow time, cost and rework due to failed adhesion of materials is of great benefit in aerospace manufacturing. Current cleaning processes typically involve cleaning with volatile organic solvents.  Solvent cleaning has several aspects that provide opportunities for improvement:  labor intensive, removal of difficult contaminants, environmental health and safety considerations such as waste, ergonomics, confined space, and flammability, and cleaning complex geometries.

Boeing is investigating a robust cleaning process using carbon dioxide (CO₂) composite spray.  Replacing solvent cleaning with CO₂ composite spray could provide significant improvements in manufacturing including reducing cost and flow time as well as providing a more consistently clean surface which will reduce rework. CO₂ composite spray also has the added benefit of being much more environmentally sustainable by eliminating the use of organic solvents and reducing waste.  CO₂ composite spray cleaning has been demonstrated to successfully clean a wide variety of cutting fluids, greases and oils which commonly cause adhesion failures when not cleaned properly in the aircraft manufacturing process. The CO­₂ composite spray system has shown that both metallic and composite surfaces are successfully cleaned by testing with Fourier transform infrared spectroscopy and paint and sealant adhesion testing.