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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Newbie questions why plated-in-China nickel and chrome is peeling
2003
Q. Hi,
I'm hoping someone can help me out with an answer(s) or pointing me towards documentation or other sources of help.
I sell arts and crafts kits, focusing on a certain group of crafters using mostly metal parts, and generally plated. Anyway, I ordered a couple thousand cone shaped wine stoppers, chrome plated from a vendor in China. One of my customers unfortunately told me that she had found a couple of peeling stoppers, and later told me that a couple of other stoppers she had in vinegar ⇦in bulk on eBay or Amazon [affil links] jars for two weeks were now peeling. My vendor says maybe its because they tried to rush the order and they may not have waited long enough between processes? Hmmm - so what are my questions:
1) Is it likely that if a few peeled, that all will peel? I've sold several hundred already, and don't want a reputation for selling junk.
2) Is there a "correct" process to follow, so I know what I'm talking about regarding plating over zinc?
3) They offered to make new ones for me but is there anything I can focus on to make sure the end-result is different (I realize that is difficult not knowing exactly what they did to screw up the first order).
4) Are there different types of chrome plating that make sense for relatively inexpensive items like this that I should know about?
5) Finally, another vendor offered me stoppers that have polished nickel plating - to me the look is close enough, but is nickel plating any better or worse than chrome?
6) Oh and maybe one more...what kinds of questions should I be asking when ordering plated objects to make sure I don't buy junk?
Any help would be greatly appreciated! I know its a long list to tackle.
Larry RubinArts & Crafts - Newton, Massachusetts, US
A. Hi Larry. We've posted your inquiry, but a hundred things have to be done right for quality plating, so a lot can go wrong, and it's hard to guess which things were done poorly. It is very difficult for a buyer to do the troubleshooting even if they have expertise and can visit the plating shop; you usually have to rely on the plating shop to figure it out. With little expertise and relying on a shop 12,000 miles away, your only realistic option is probably to use a different plating shop. So far we can count on the fingers of one hand the number of technical responses we have received from China. I'll keeping my fingers crossed, but it will be a surprise to me if any Chinese plating shops help you create a list of what quality measures are often skipped in China and what problems that causes.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003
Q. I am not looking for an answer from a Chinese shop. I am looking for generic answers from anywhere, giving basic explanations please.
Larry Rubin [returning]- Newton, Massachusetts
2003
A. Like a computer-garbage in-garbage out. When you go to the lowest priced vendor you will frequently get the lowest quality. Peeling is caused by poor control of the process. From parts not clean, totank parameters not properly maintained, or poor rinsing, or stopping for too long between critical steps, or wrong process chemicals for the use/part/metal, to mention just a few.
James Watts- Navarre, Florida
2003
A. I realize you are hungry for answers, so mine may help. First of all, your substrate appears to be die cast zinc, a poor choice for application in vinegar or wine. You parts are probably already plated in nickel with a thin layer of chromium over that to protect the nickel from corrosion. The nickel, not chromium, is peeling. With die cast zinc, I believe that most problems are related to the substrate -- either itself or its cleaning. Plating accentuates pores, it does not fill them like paint. Any porosity in the substrate is a hole where it can be attacked, peeling the plating. There are shops that can make and finish such parts pore-free, but probably not at China prices.
Paul Morkovsky
- Shiner, Texas, USA
2003
September 2014
A. Hi again Larry.
1. It's difficult to guess whether they'll all peel, but probably not; probably some got clean enough for the plating to stick.
2. Yes, there are generally correct sequences to follow; most plating texts including the Electroplating Engineering Handbook will list those sequences. But if you read the 15-20 step sequence, you're still left with the issue that all the correct parameters must be held for each of those 15+ steps. Further, as Paul says, zinc diecastings are a poor choice for the application, and careful quality control of the castings is required to insure no porosity or cold shuts.
3. As we've all said, it just won't prove practical for you to issue a list of required process improvements. Sorry.
4. These items are probably vibratory finished, cleaned, acid dipped, cyanide copper plated, nickel plated, then chrome plated. It's highly unlikely that the chrome itself is the problem and that you can fix the problem by focusing on it.
5. Your current stoppers are surely nickel plated, then chrome plated. Skipping the chrome step won't improve their quality.
6. You should ask what the substrate is, what QA tests are performed on it before plating, and what is the exact plating sequence.
Best of luck, but again, you can't solve it -- all you can do is buy from shops that will solve it.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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