Alkaline Soak Clean

STATION 1. Alkaline Soak Clean

The purpose of the alkaline soak cleaner is to remove any oil, grease, shop dirt, fingerprints, or similar films left on the parts after manufacture. Surface contaminants present on the parts during electropolishing can lower the quality of the resulting finish, particularly for critical applications such as medical, pharmaceutical, and semiconductor products. Once the parts are removed from the cleaner, care should be taken to avoid unnecessary contact with the hands or process equipment.

Alkaline cleaning proceeds by a combination of chemical and physical reactions involving displacement, flotation, penetration, wetting, emulsification, and saponification of the contaminants. All of these reactions are sensitive to both time and temperature; therefore, care should be taken to make sure the cleaning conditions fit the properties of the soil to be removed. Some soils may require little or no alkaline soaking; others may require substantially higher temperatures, soaking times, and chemical concentrations to achieve cleanliness.

Cleanliness should be considered one of the cardinal principles of all metal finishing operations. Improperly or inadequately cleaned parts are a frequent source of rejects. Alkaline cleaners are relatively cheap insurance, compared to the cost of rework. Cleaning baths should be maintained by:

1. Periodic additions of cleaning compound to maintain sufficient alkalinity, wetting agent, and performance, as determined by on-site testing.

2. A preventive maintenance schedule to dump and remix the solution before cleaning problems can affect the quality of the work.

Alternative cleaning methods include organic solvent cleaning and vapor degreasing; however, these methods seldom leave a water-wettable surface, and some alkaline cleaning may be required to remove any residue from the organic cleaner.