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-----Minute pinholes in clusters after plating
Q. I am working on a problem in plating on motorcycle forks.The forks are made up of 'cold drawn welded' tubes. The tubes are ground and the nickel and hard chrome plated (totally 20µ in thickness). There is some peculiar phenomenon after plating. Some tubes develop minute pinholes in cluster. Can this be due to something wrong in the tube metal or tube formation process.
DHANANJAY LAXMAN SHEDGEQuality assurance services - PUNE, MAHARASHTRA, INDIA
2003
A. Anything is possible. Are the 'pinholes' bright and semi-hemispheric? If so they are hydrogen pits, sometimes called gas pits. It can be as simple as insufficient wetting agent, but if the pits are clustered, probably not. A knowledgable plater once told me that he had proven to himself that scotchbrite pads can actually melt on a power buffer, such that overbuffing a spot with scotchbrite can account for these small cluster defects. I've never had the opportunity to prove or disprove it, nor heard any other plater confirm or refute it.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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2003
A. Ted, you are confirmed. I have done it and it is a mess. My guess is that there is embedded grinding material that is causing treeing which breaks off leaving pit like holes. A thought would be to use an aluminum oxide based material which will dissolve in a strong hot alkaline cleaner.
James Watts- Navarre, Florida
2003
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