R TASK 70-62-18-380-011
R LOCAL ANODIZING OF ALUMINUM PARTS
R 1. General.
R This procedure is used for applying local anodizing on
R aluminum and aluminum alloy parts using a sulfo-chromic
R solution.
R This process allows either local touch-up or renewal of an
R existing coating.
R 2. Equipment.
R The following equipment is required for the application of
R this process:
R A. Safety equipment and devices which are standard equipment
R in surface treatment shops such as: eye bath, emergency
R showers, protective clothing against electroplating
R products and means for neutralizing acid or alkaline
R splashing.
R B. Processing plant for neutralizing waste and used solutions.
R C. Efficient ventilation system for extracting and
R neutralizing vapors.
R D. Water rinse tank used after sulfo-chromic cleaning
R must be made of steel lined with high density polyethylene
R or polypropylene and equipped with a water spraying system.
R E. The electrolytic degreasing solution shall include:
R (1) An anode (swab) made of graphite.
R (2) A 0 to 15 volts D.C. power supply with amperage
R adjustable from 0 to 100 percent.
R F. The chromic anodizing solution shall include:
R (1) A cathode (swab) made of stainless steel.
R (2) A 0 to 50 volts D.C. power supply with amperage
R adjustable from 0 to 100 percent that can be easily
R monitored.
R (3) A circulating pump.
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R 3. Materials.
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R Solution Operating Temperature
R Materials No. °F °C
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R A. Solvent
R (1) Acetone CP1039 Ambient
R (2) Isopropyl alcohol CP1041 Ambient
R B. Electrolytic degreasing CP2605 Ambient
R Solutions.
R C. Sulfo-chromic acid solution CP2606 Ambient
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R 4. Procedure.
R WARNING: SOLUTIONS ARE VERY ACTIVE AND CAUSE SERIOUS BURNS.
R AVOID CONTACT WITH SKIN, EYES, AND CLOTHING. AVOID
R BREATHING VAPORS. IF CONTACT OCCURS, WASH
R IMMEDIATELY WITH ABUNDANT QUANTITY OF WATER.
R OPERATORS SHOULD WEAR FACE SHIELD, GLOVES,
R PROTECTIVE CLOTHING, AND PROTECTIVE SHOES.
R A. Clean surface to be coated with solvent degreaser listed
R paragraph 3.A., using a clean brush or lint-free cloth.
R B. Slightly unpolish area to be touched-up using pumice
R powder with water.
R C. Rinse by immersion in water. Water film must remain
R constant.
R D. Perform electrolytic degreasing operation by saturating
R the anode swab (or stylus) with the solution listed in
R paragraph 3.B. and rubbing gently on the part area.
R Voltage : 10-15 volts D.C.
R Current density: 3.2-12.8 Amp/in2 (50-200 A/dm2).
R Duration : 1-3 minutes.
R E. Rinse by immersion in water. Water film must remain
R constant.
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R WARNING: SOLUTIONS ARE VERY ACTIVE AND CAUSE SERIOUS BURNS.
R AVOID CONTACT WITH SKIN, EYES, AND CLOTHING. AVOID
R BREATHING VAPORS. IF CONTACT OCCURS, WASH
R IMMEDIATELY WITH ABUNDANT QUANTITY OF WATER.
R OPERATORS SHOULD WEAR FACE SHIELD, GLOVES,
R PROTECTIVE CLOTHING, AND PROTECTIVE SHOES.
R F. Perform anodization operation by saturating with the
R solution listed in paragraph 3.C. the hollow cathode swab
R (or stylus) and rubbing gently on the part area. The
R solution must be recirculated from the tank to the cathode
R using a pump.
R Voltage: 0-50 volts D.C.
R Duration: 1-2 minutes.
R NOTE: It is imperative to closely monitor the amount of
R current delivered in the system in order to avoid
R overheating of the part and the solution.
R G. It is highly imperative that voltage be applied gradually
R above 25 volts within 10 seconds period or porous coating
R may occur.
R WARNING: CHROMIC SOLUTIONS ARE VERY ACTIVE AND CAUSE SERIOUS
R BURNS. AVOID CONTACT WITH SKIN, EYES, AND
R CLOTHING. AVOID BREATHING VAPORS. IF CONTACT
R OCCURS, WASH IMMEDIATELY WITH ABUNDANT QUANTITY OF
R WATER.
R OPERATORS SHOULD WEAR FACE SHIELD, GLOVES,
R PROTECTIVE CLOTHING, AND PROTECTIVE SHOES.
R H. Rinse by immersion in water.
R I. Rinse by immersion in lukewarm water at (60°C) 140°F.
R J. Dry using clean, dry air or in a dust free, ventilated
R oven heated at 60-70°C (140-160°F).
R K. Remove masking if previously applied.
R 5. Quality Control.
R A. The coating must show a uniform color. Check for absence
R of powdery residues.
R B. Visually check that the coating covers evenly the area to
R be covered.
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