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Electro nickel salt spray test and peeling after plating

2004

I'm a Sales Engineer for a machine shop that manufacture turn parts by using auto lathe machine. We manufacture shaft and standoff for printers and these part are electro nickel plated after manufacture.

1)Lately our customer feedback that the parts we send show some corrosion for the shaft and they wish to find our what's the root cause of the corrosion and how many hour of salt spray test can electro nickel withstand if plating thickness is 3-5um. We had send some samples for salt spray test, in general the result show corrosion at 12 hours. Does anyone have any information regards the number of hours should electro nickel withstand during salt spray test.

2)As for the standoff(Male & Female) that we manufacture the female side which is the internal thread which also causes corrosion due to electro nickel plating are unable to penetrate into the internal thread(about 6-7mm depth.

After discussion with plater they suggested to plate a layer of copper first than follow by the electro nickel, as the result this will minimize the corrosion in the internal thread, but lately there's an issue that the surface show some exposed copper may due to peeling. Is there anyone could help to provide us some information that causes this to happen as our customer also wish to find out more about the root cause.

Bryan Heng Joo Soon
Machine Shop (Turn Parts) - Singapore

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GM,

There are several parameters which can contribute to the problem you have. Still, low chloride in your Nickel bath may cause poor leveling and not withstanding neutral salt spray test. Hence, check for the bath chemistry.

Shankara Narayanan N
- Bangalore, Karnataka, India
2004

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2004

Dear Sir,

3~5 Micron of Ni plate will not provide any substantial corrosion protection. Ni plating is still porous up to 5 microns. If you know how many hours Salt spray you need to achieve, then check with the supplier of the plating chemistry for a plating spec. There are many different specs for Ni plating that will give years of corrosion resistance. However, 3~5 microns is not one of them.

Regards,

Jonathan Timms
- Hong Kong