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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing 1989-2024
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Zinc Plating Peels off Stainless Steel during Crimping Process
Q. We are facing issue related to flaking/peel off during the crimping process.
The trend of peel off is highly erratic & random with no correlation with any critical stage.
What can be the root-cause of this?
How can we improve adhesion of Zinc plating with chromating on SS alloy?
Shubham Joshi
- Haryana, India
July 24, 2024
A. Hi Shubham.
Let's start with these two questions please:
• Are you doing a Wood's Nickel Strike, or any strike, before the zinc plating?
• Do you know what stainless steel alloy you are trying to plate onto?
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I hate to always be "that guy", but another pertinent question here is why do this in the first place? Coatings like this are generally used for corrosion protection on carbon steel. There is no reason I can think of to pay extra for stainless steel and the corrosion protection inherent in its alloy composition, only to make that a moot point by covering that surface with a coating. Especially in the case of plating, given that plating stainless is more difficult than plating regular steel. (Plating stainless requires surface "activation", which is the opposite of the passivity that stainless is intended to have.)
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
Q. Yes, the grade is ASTM A36.
It is something which is required for one of my customers exporting parts to Europe.
Keeping SS aside, what could be the possible reason for the same issue in MS metallurgy. We have already tried trials keeping the current density on the lower side but it has negatively impacted the adhesion.
- Haryana, India
July 25, 2024
A. Hi again.
ASTM A36 is the MS grade, not the stainless steel. Poor adhesion in this rather different case is most often due to inadequate cleaning...
• Have you observed a waterbreak-free surface after the cleaning rinse and after the acid dip rinse?
• Have you tried scrubbing a few sample parts with a tampico brush
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I am trying to make this situation less abstract because I feel that it is the path towards progress, but you seem to be trying to keep it abstract 
I don't think "Keeping SS aside ..." is an appropriate answer to "are you doing Wood's nickel strike" and "what grade of SS?" .
Yes, it may be two different issues, but it may not be. If you're doing proper pretreatment on the stainless and there is poor adhesion there as well, it could be something like silicones being used in the shop).
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. JOSHI,
Zinc plating peel off from plated part, Check the chemistry in zinc bath, Due to high zinc thickness on part. Do water break test, PART may not clean enough.
- Sterling Heights
October 8, 2024
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