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Defects in Nickel-Chrome Plating on ZAMAK-5 base material

We are facing a problem of "Bubbles", "White Wash" & "Pitting" on the surface of our product Knob after Ni-Cr plating. The Results are in-consistent. We follow the standard process like: SOAK cleaning, CATHODIC, ACID CLEANING, CYANIDE-COPPER, ACID-COPPER, Semi Ni, Bright Ni and finally rinsing in Chrome bath.We have a continuous Air-Agitation & Filter unit at Bright Nickel, & Acid-Copper baths.

Appreciate your suggestion to improve our quality of Knobs.

Girish Bhavsar
engineer working in electroplating plant - Pune, Maharashtra, India
December 30, 2009

Hi, Girish. The first step is probably to get the process supplier in to give you some guidance. If that is not practical, you can retain a plating consultant. You are describing at least three separate defects which are all usually due to widely different causes. Countless technical papers, seminars, and book chapters have been devoted to each of the three. You are unfortunately quite unlikely to solve these three problems without bringing experienced help to bear on the problem.

But I would start with the blistering (bubbles) problem because this is caused by problems early in the treatment cycle whereas the white wash is caused by problems very late in the cycle -- and it makes little sense to fine-tune the last step of a process that is failing early on. Best of luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 30, 2009

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December 30, 2009

GIRISHBHAI
KINDLY INFORM THE WHOLE PROCESS CYCLE INCLUDING SOAK CLEANING TIME,CATHODIC CURRENT &TIME, CONCENTRATION OF
ACID, SWILLS ,CYANIDE COPPER SEQUENCE WITH CURRENT,TIME & MAKE, EVERY PARAMETERS OF SEMI AND BRIGHT NICKEL
I HAVE WORKED WITH ZAMAK FOR FIFTEEN YEARS

SUNIL GADHIA
- RAJKOT, GUJARAT, INDIA

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January 4, 2010

Hi,

Please check the process again by avoiding cathodic cleaning,instead try by ultrasonic cleaner or cleaning the component by manually TCE, secondly increase the time in cyanide copper with very low current and agitation(observe the gassing to be very low).

Praveen Kumar
plating process supplier
Mumbai, India