Zinc plating is either too thin or it bubbles
January 12, 2018
Q. Dear all,
We are manufacturers of sheet metal components and we are facing a problem with zinc plating as follows ...
For "coupling disc" (circular part) we are required to maintain the DFT up to 10 microns by providing current 16 Amps/sq.foot. But whenever we maintain the same, bubbles are formed at outer edge of the disc and if we minimize the cycle time, DFT decreases, which is not acceptable for our customer.
Awaiting for Your valued reply.
A. Hi Shailesh. I am having a little trouble understanding you, but I think you are saying that you need 10 microns of plating thickness but the plating gets 'nodules' (or perhaps 'blisters') if you raise the current high enough to meet that thickness specification?
Why not just plate for a longer time instead of raising the amperage? Since you are unable at present to successfully plate at 16 Amps/sq. foot, do you have any evidence that you ought to be able to plate at that rate?
Is this acid zinc plating or alkaline zinc? Does all of your work have a 10 micron thickness requirement, or does some of your work get thinner plating? Thanks. (P.S.: I've personally never heard the phrase "DFT/dry film thickness" applied to zinc plating).
Ted Mooney, P.E. RET
Pine Beach, New Jersey
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