Vapor degreaser easily cleans and dry complex parts for surface prepping or packaging.
Photos courtesy of MicroCare Inc.

Ever-changing environmental restrictions and workplace safety rules faced by aerospace manufacturers today require cleaning and surface preparation methods and cleaning fluids that clean parts effectively while meeting strict regulatory and environmental sustainability standards.

Many finished metal aerospace parts are tested using black light inspection, particle count, water break testing, or other analysis to ensure they meet the quality requirements. Often extremely small with intricate geometries, awkward shapes, and internal blind holes, aerospace parts are becoming more difficult to clean, especially without damaging the substrate or impacting the final finish.

To achieve quality metal aerospace components, ensure a superior finish through parts cleaning and surface preparation. Metal components must be perfectly clean before anodizing, plating, painting, welding, or other downstream processes. The smallest amount of surface contaminant – machining oil, grease, lubricants, polishing pastes, adhesives, wax, marking inks, fingerprints, or production debris – can interfere with finishing. An inferior quality finish can detract from the parts’ final appearance and result in part failure.

Vapor degreasing

A long-term cleaning solution, vapor degreasing achieves a quality finish while supporting worker safety and environmental sustainability. Vapor degreasing, combined with modern, advanced cleaning fluids, makes surface cleaning simple, consistent, and sustainable. Vapor degreasing is fast, efficient, high throughput, and can easily be automated into standard production lines. The closed-loop system uses a specialized low-boiling, non-flammable fluid as the cleaning agent.

The machine contains two chambers: a boil sump and a rinse sump. The boil sump dissolves or lifts debris from soiled parts immersed in the chamber. In some instances, ultrasonic agitation adds extra cleaning power. As the parts lift from the cleaning fluid, they are briefly rinsed in the rinse sump or in the rinsing fluid vapors. After a typical cycle of about 6 minutes to 20 minutes, the parts come out clean, completely rinsed, dried, spot-free, and ready for finishing.

Modern fluids

Most modern vapor degreaser cleaning fluids include hydrocarbons such as mineral spirits or alcohols such as isopropanol and ethanol. How the ingredients combine determines the cleaning fluid’s effectiveness and its material compatibility. The vapor degreaser can use a single cleaning fluid or fluids can be mixed, blended, or custom formulated to remove a specific soil from a specific substrate, maximizing cleaning effectiveness.

Modern fluids can trap and remove soils from highly complex and intricate component designs and geometries. For aerospace parts cleaning, chemical formulations can have low surface tension and extremely low viscosity, allowing them to penetrate and clean very tight spaces such as blind holes and the crevices between stacked parts. Most vapor degreasing fluids are also heavy and dense, typically 20% to 40% heavier than water, which aids in dislodging particulates from the components. While they are powerful cleaners engineered for specific aerospace applications, delicate parts are easily cleaned and dried without damage.

The vapor degreaser contains two chambers for cleaning and rinsing parts.

Sustainability

While aerospace parts cleaning and finishing processes face increasing environmental regulations, regulators are also scrutinizing cleaning fluids and fluid disposal methods. Vapor degreasing addresses both concerns.

Many modern fluids have green credentials with formulations that offer improved environmental properties such as very low global warming potential (GWP) to reduce greenhouse gas effects. They also have zero ozone depleting potential (ODP) and low volatile organic compound (VOC) content. This allows them to meet strict regional air quality regulations. Many are not considered a hazardous air pollutant (HAP). They also follow global environmental directives including the European F-Gas and Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) legislation.

Another environmental benefit of vapor degreasing fluid is their capacity for recycling. Fluids work repeatedly for hundreds of cycles before needing to be refreshed or replaced. Additionally, vapor degreasing concentrates soil and contaminants as it works, reducing waste generation and lowering hazardous waste disposal costs.

The systems use no water and little electricity. Other processes, such as aqueous cleaning, require lots of energy for water heating and wastewater processing. The latter includes filtering, distillation, deionizing, and osmosis prepping for disposal.

Worker safety

In addition to environmental benefits modern sustainable cleaners improve worker safety. Unlike older solvents, modern cleaning fluids are non flammable, protecting workers from burn accidents.

Additionally, modern sustainable cleaning fluids are better for worker exposure. The Permissible Exposure Limit (PEL) is a toxicity rating measured in parts per million (ppm). Lower numbers specify greater risk. For instance, trichloroethylene (TCE) has a 100ppm PEL and normal propyl bromide (nPB) has just a 0.1ppm PEL, so, they should be used with caution. Cleaning fluids with PELs of 200ppm to 1,000ppm (the highest rating possible) are a better alternative. The permissible exposure limits of the new sustainable cleaning fluids are about 200ppm to 250ppm, making them considerably safer for exposed workers than the older solvents.

Modern cleaning fluids offer high solvency to rigorously clean and displace production debris and soils.

Cost

Factoring in all the benefits – low energy consumption, reusability, reduced safety equipment needs – vapor degreasing can reduce operating costs. It cleans quickly and effectively, so parts come out of the vapor degreaser ready for the next stage in the production process, increasing facility throughput and productivity.

And, modern fluids can often be used in existing equipment. This allows the same operating methods without impacting cleaning methods. After emptying and cleaning the vapor degreaser of the old fluid, the replacement cleaning fluids are put into the machinery. No training or other changes needed.

Conclusion

Cleaning is critical to achieve a high-quality aerospace parts surface finish. By using a vapor degreaser and modern, advanced cleaning fluids, the cleaning process is simple, consistent, and sustainable, producing perfectly prepped parts. Vapor degreasing is cost-effective in ensuring parts are clean, and it addresses worker safety, regulatory requirements, and environmental concerns.

It is a flexible process that readily adapts to changes in cleaning requirements, a regulation change, or new environmental concern.

MicroCare Inc.

About the author: Venesia Hurtubise is a technical chemist at MicroCare. She can be reached at techsupport@microcare.com.