Metal Finishing Guide Book

2012 Organic Finishing Guidebook Issue

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Fig. 3. Sequence of operations for heavy zinc or manganese phosphating. for the zinc phosphating processes and if a manganese-phosphate process is used, a manganese-iron phosphate crystal is developed. The process specifics for the processes will vary but some guidelines are as fol- lows: (1) Phosphate coatings with coating weights up to 4,500 mg/ft2 are de- posited by processes with long immersion times and high temperatures. Tines can be as long as 60 minutes and temperatures are in the range of 180–205°F. (2) Phos- phate processes containing accelerators, such as nitrates, produce zinc or man- ganese phosphate coatings with coating weights in the range of 1,000–3,500 mg/ft2 with treatment times in the area of 5 to 15 minutes. Temperature range is between 130°F and 200°F depending on the process. The coatings can also be treated with coloring agents so that the appearance of the parts can be varied to 40

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