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Letter 41080
Zinc Yellow Vs Zinc Phosphate
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We have been doing Zinc phosphate for valve parts. Material is
4130. Most of the parts have threads and many of those do not gauge
properly after zinc phosphate. Sometimes, a layer of loose particles
is stuck in the thread grooves which may be causing thread gauging
problem. To avoid this, can we switch over to Zinc-yellow plating?
Will there be any problem if one out of two mating parts is
Zinc-yellow and other is Zinc Phosphate? If we know of the advantages
and disadvantages of Zinc-yellow and Zinc Phosphate, it will help in
making the decision.
Thanks,
AMAR SHELKE
MANUFACTURING - Pune, India
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Lots of companies zinc plate fasteners. The threads have to have
an allowance for the plate. I think that it works better with a
thread that is also truncated, which lowers the extremely high
current density on the sharp point.
It will require a cyanide zinc plating tank or a specially tweaked
alkaline tank for best results.Barrel plating is common as it can use
a low current density for a longer period to get the most even
deposition.
For your phosphate, look into using a calcium modified zinc
phosphate. It has much smaller crystals, and if you pay close
attention to the operation of the tank, it produces a beautiful,
uniform coating that holds oil very well.
All of the above is my opinion and I do not sell material.
James Watts
- Navarre, Florida
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