MIL-STD-2197A(SH)
4.8 Methods of inspection.
4.8.1 Visual inspection. Color matching shall not be required. The plating shall be smooth, fine-grained, adherent, and free of visible blisters, pits, nodules, porosity, and excessive edge build-up when examined with normal corrected vision without magnification. Burned deposits are not acceptable. Magnification may be used to determine the significance of a condition which has been found with the unaided eye. Stains on unplated areas from rinse water or solution run-off shall not be cause for rejection.
4.8.2 Adhesion tests. Contact plated surfaces shall be tested using an adhesion test. The tape test is an adhesion test and is the generally accepted test in the selective plating industry. The tape test shall consist of applying a 1-inch wide strip of Minnesota Mining and Manufacturing Tape code number 250, or equal, across the freshly plated but thoroughly dried surface and on a location where the plating meets the unplated surface, whenever feasible. Apply the tape with heavy hand pressure and remove the tape with one quick motion perpendicular to the plated surface. Any plating adhering to the tape shall be cause for rejection. Subsequent machining or grinding of Class 3 jobs is an adhesion test, since improperly bonded coatings fail during grinding. If the manufacturers of the plating solutions provide instructions on how to machine or grind electroplated parts, produced with their product, these machining and grinding instructions shall be followed when machining or grinding the electroplated parts.
4.8.3 Thickness of deposit. Deposit thickness on the workpiece shall be determined by the before and after dimensional measurements whenever possible. When measurement cannot be made, the thickness shall be estimated from area and ampere-hour data.
4.8.4 Dye penetrant inspection. Dye penetrant inspection of Classes 3 and 3A applications shall be in accordance with NAVSEA T9074-AS-GIB-010/271. Use a visible dye penetrant (Type II). Use a post emulsifiable, lipophilic removal method (Method C). Use a nonaquious development form (Form D). Any defect greater than
0.0625 inch in length shall be cause for rejection.
5 DETAILED REQUIREMENTS
5.1 Types of damage which can be repaired. Brush electroplating may be used to repair any type of damage which does not result in structural weakening. Cracks and substantial loss of material, particle pull-out from gears, very deep or very large pits which compromise pressure boundary integrity, and damage to case hardened surfaces with hardness greater than HRC 45 cause structural weakening and may not be repaired. Wear, scoring, corrosion and mismatchining do not cause structural weakening and may be repaired. Examples of damage which cannot be repaired are.
5.2 Repair of pits and scores. Pits and scores shall be filed, honed, ground, or electrochemically machined dish shaped to remove steep walls and sharp corners. On shafting with scored or smeared metal at the journal, all smeared metal shall be removed so that brush electroplating is on undisturbed base metal.
5.3 Classification of repairs. Applications shall be classified as follows (see 5.4 to 5.7).
5.4 Class 1 (corrosion-resistant) coatings. Allowable thickness shall be governed by practical and economical use of the metal or metals deposited and shall be restricted to the qualification limit of the procedure. Three types of corrosion-resistant coatings may be repaired by brush electroplating: sacrificial coatings (zinc or aluminum), noble or semi-noble metal coatings (gold, silver, chromium, or nickel), and anodized coatings. Sacrificial coatings may be repaired with electroplated zinc. Noble or semi-noble metal coatings may be repaired by applying the same metal as was present before being damaged. An exception is chromium which shall be repaired with nickel or cobalt patches; when appearances are all-important, a thin coating of chromium may be used. Anodized aluminum may be repaired using an anodizing solution (refer to contractor's instruction manual).
5.5 Class 2 (static contact) coatings. Allowable thickness shall be not greater than 0.030 inch exclusive of filling pits, scores, dents, and other imperfections, when the total surface area of the defects comprises not greater than 10 percent of the area to be plated. The maximum allowable plating thickness shall not exceed the qualification limit of the procedure. Class 2 coatings are generally for surface restorations for purposes of sealing or fit, or to electrical conductors. The following paragraphs show the type or types of repairs and repair procedures to which
this class is applicable.
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