Tinker Air Force Base - Oklahoma City, OK
CO2 blasting is used to remove carbon, corrosion, and paint from jet engine components. In the past, these operations were accomplished by using solvents, acids, and caustics to chemically remove the material. This process required large vats of chemicals where parts would be soaked for several minutes to several hours.
Another use of CO2 blasting is to replace traditional grit blasting. When grit blasting parts with internal cavities, it is necessary to mask the part to avoid grit entrapment. CO2 blasting eliminates the need for masking, since the solid CO2 sublimes to a gas upon impact.
CO2 blasting was installed in 1988, and is used primarily as a cleaning supplement. In this process, an operator works in an enclosed booth using a full face respirator by manually directing the CO2 gun at the part. The gun propels CO2 pellets at a high flow rate (8 pounds per minute). The cleaning is accomplished by the force of the impact which causes the solid CO2 to sublime to a gas. The removed soils can then be collected. Smaller particles are removed from the air by a filtration system. Larger particles such as paint chips and carbon deposits are swept from the blast booth floor.
This process is used primarily for two purposes. The first is for spot or touch up cleaning. When a part is not completely cleaned in the chemical cleaning line, the CO2 blast unit is used to clean the soiled area. This results in reduced chemical usage. It also allows the part to be processed faster, since it does not have to be reprocessed through the chemical cleaning line.
CO2 blasting is also used in place of grit blasting on parts with internal cavities. Internal cavities must be masked before grit blasting to prevent grit entrapment which could cause damage to the engine. Since CO2 sublimes from solid to gas, cleaning can be accomplished without grit entrapment and without masking. This results in reduced hazardous waste from masking and quicker processing times.
This process has resulted in reduced chemical usage and quicker processing times. CO2 blasting has eliminated a total of 1,700 gallons of chemicals per year. These chemicals include methylene chloride, orthodichlorobenzene, cresylic acid, and caustic solutions. The hazardous waste disposal associated with these chemicals has also been eliminated.