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Acid chloride zinc cleaners v/s Alkaline zinc cleaners

 

I am experiencing a cloudy condition on a part plated in an alkaline zinc process (with yellow chromate). Even after strip and replate it is still present. However I can take the worst case part strip it and replate it on an acid chloride zinc line and there is no sign of cloudy condition. Due to further processing of this part acid chloride is not an option. It is my understanding that there is very little difference between the cleaners and concentrations of acid v/s alkaline lines, so why would there be so much of a difference between the ability of one to clean this condition and not the other. I realize there could probably be several causes, so if anyone responds could you please list them in order of probability if possible.

Any information that may be relevant would be appreciated.

Thanks and regards,

Kevin Davis
- Versailles, Kentucky

It sounds like you have a problem with 1 or more process solutions on your alkaline line. You first need to determine where in the line the condition occurs i.e. after cleaning, pickling, plating, chromating. Then look at the chemistry. An alternative, if possible is to process the part through the preplate cycle of the chloride line, then plate on the alkaline line. If the problem is not extant then the problem is the preplate cycle. If this does not work then go to the other end. Run through plate on the alkaline line and go to the other line to chromate. What you are trying to do is control the variables and determine where the condition is occurring. You should, of course, talk to the supplier of your proprietary chemistry.

Gene Packman
process supplier - Great Neck, New York
 

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What is the base material being plated?

  
Tom Pullizzi
Falls Township, Pennsylvania
 

The base metal is SAE 1215 machined from bar stock. I am sorry for not replying sooner I have been traveling. Also I am actually the end user of the plating, so I don't have the ability to work with the chemical supplier. Your input is appreciated.

Kevin Davis [returning]
- Versailles, Kentucky