Archive for Metal cleaner

Apr
04

Metal Cleaner

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Cleaning is one of the final steps in preparing a metal surface for plating. In addition to the presence of natural oxide films and normal shop soil on metal parts, surface of the metal parts are also covered by quenching oil, rust proofing oil, drawing oil, stamping lubricants, heat scales, and even zinc phosphate coatings. Hence, the soil to be removed before electroplating process can be a very complex mixture and its condition and ease of removal will change with aging. Its required metal cleaner to help removed complex soil.

Type of Metal Cleaner

Solvent Cleaners

Solvent cleaners should be used to remove large excesses of oil and grease. Vapor degreasing method tends to remove oil from solid dirt particles without always removing the solids. The dirt particles left on surface. Hence, alkaline cleaner will difficult to remove the dirt particles. Solvents remove fats, oils, resins, waxes, paraffin, and the like. Normally solvents can be used: Trichloroethylene (TCE), Methylene Chloride (MEC), Perchloroethylene (PCE), kerosene, and mineral spirits.

By the addition of oil soluble emulsifiers to solvents, the solvent emulsion cleaners are produced. The solvent emulsion cleaners are particularly useful in removing dust and other solid particles mixed with oils and greases or buffing compounds. The metal still retains and oil film, however, so that it is necessary to alkaline clean before electroplating.

Alkaline Cleaners

Alkaline cleaning material must be soluble in water. It takes a combination of alkalis with the proper soaps or surfactants, chelating agents, softening agents, sequestering agents, corrosion inhibitors, and other chemicals to get maximum metal cleaner effectiveness.

Alkaline metal cleaner can be used by soak or spray cleaning. Generally, soak cleaner works at 82oC up to boiling for 3 to 15 min, and spray cleaners are used at 74oC with spray pressure from 0.7 to 3.5 kg/cm2. For spray cleaners use low foaming nonionic surfactant.

Alkaline cleaning is usually followed by acid dipping. Acid dipping neutralizes alkaline films, removes any oxides that form during the alkaline cleaning, and provides a micro etch on the surface which improves adhesion at electroplating process.

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