Metal finishing Q&As since 1989

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Alternative process technology in place of Decorative Nickel-Chrome

2004

Dear Sir,

I am looking to set-up our own decorative nickel-chrome (Triple layer of Nickel) plating plant on Zinc die cast parts for Automotive industry to achieve 240+ hours of salt spray specification. I am listing our requirements and would highly appreciate your inputs on the same.

i) Could you please tell me the process technology that would be more cost effective with high quality results amp;& environment-friendly i.e. process sequence to be followed along with various parameters.

ii) Considering the stringent environment policy & subsequent regulation , the type of eco-friendly chemicals to be used. Ex. can we use other process in place of cyanide copper to eliminate cyanide this way. Also can we use other chemicals in place of hexavalent chemicals. If it is possible could you give me a formula and operating condition for the bath.

iii) How to reuse the waste water.

iv) To meet the environment regulation the type of air and water control device needed.

I greatly appreciate your valuable inputs on above, with best Regards,

SUBHASH CHANDRA JHA
plating shop - NOIDA, U.P., India

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2004

Hello Subhash

i). If environmentally-friendly replacement technologies were more cost effective and offered higher quality, they would be immediately adopted. Rather, they are more expensive not less expensive, and they present more QA problems, not less. But they can certainly be an excellent idea for the greater good despite the costs and QA problems and, as we see in consumer industries, expanded use may bring down the costs.

ii). I am not personally aware of affordable and production-proven replacements for copper cyanide on die-castings but possibilities include: special nickel strikes (used successfully on steel, but I don't know their success rate on die castings); pyrophosphate copper plating (theoretically do-able, but I don't personally know of production shops doing it); or electroless nickel (perhaps too expensive to be a realistic solution). Yes, you certainly can use proprietary trivalent chromium or tin-cobalt plating baths instead of hexavalent chromium baths; any of the larger plating process suppliers can provide these proprietary solutions. The vendors will give you the operating particulars for these processes because have been developed privately.

opinion!   An additional source of info is the numberless USA EPA funded websites on replacement plating technologies. No one can stop non-American platers like yourself from visiting these sites (which were paid for by taxes on American businesses including American plating shops) and using their contents. But apparently you've found them not even worth your time, let alone 2 cents, let alone the millions of dollars of grant money which was spent on them--which I think is a generally very valid assessment :-)

iii). The best solution is usually not to try to reuse the water at end-of-pipe, but to get the water back into the plating tanks at each individual tank via ion exchange, evaporation, or similar chemical recovery technologies. But wastewater treatment and recycling is a subject for large books, not a one-paragraph internet reply.

iv). What control devices you need depends on what processes you select, but hexavalent chromium plating requires reasonably high technology, carefully engineered dry mesh-pad recovery of chrome from the exhaust air.

Best of luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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2004

Mr Jha

It is entirely possible to set up a Zero Discharge Tri Ni plating unit where the coatings will meet and exceed the specs you have cited. In India this is possible.

Regards,

Asif Nurie [deceased] [deceased]
- New Delhi, India
With deep sadness we acknowledge the passing of Asif on Jan 24, 2016