Where the
world gathers for metal finishing
Q&As since 1989


-----

Water marks, rusty parts and thick electroplating

2003

I hope I can have some advise on the problem that I have here. I am an engineer for a metal stamping company, and we supply metal stamped parts for a Japanese bar coding machine manufacturer. Almost all of their parts require electroplating, which includes rainbow, black zinc, and nickel plating. All of these plating were actually sent to my electroplating supplier. These parts that were sent have repetitive problems, and my electroplating supplier was not able to provide me with reasonable answers to solve the problems which I encounter.

I have 3 problems which I would want to point out here, which are:

a)For the black zinc metal parts, there are presence of rainbow colour and also white spots on the metal parts. The Japan company employs 0% defect and and irregularities on the appearance is unacceptable. Nevertheless the electroplating supplier's answer for this defect is chemical problem, and until today these problems still persist.

b)The second problem which I encounter is for nickel plated metal parts. From the front surface, the finishing of the nickel plated part is shiny, and the other side is not that shiny compared to the front part. This is a normal phenomenon but at the edge of bending parts, yellow spots occurred which leads to rusty part. Our part is rejected by the Japanese company as the part always get rusty when it reaches their assembly line. Is there any way to solve this, or shall we have a certain packing style to avoid this problem?

c)The last problem which I encounter, is the inconsistency of nickel plating thickness. My customer requires me to control the plating thickness to be 1, 2 or 3 micron depending on parts. Nevertheless, my electroplating supplier was not be able to control the thickness and causes my metal parts to be rejected due to dimensional problems. These nickel plating gets very thick in the hole of the metal part, and cause the hole to get smaller after plating due to the thicker plating. Normally these holes in the metal parts, have a spec of plus/minus 0.01 or 0.02 tolerance. My supplier could not solve this problem even after one year.

Hope that anybody have any experience could be able to solve my problem.

Thank you,
Keith

Keith Low
electronics metal part supplier - Kuala Lumpur, Wilayah Persekutuan, Malaysia

Dear Keith,

One of the best ways is to change your plater, because from last one year he is not able to solve your such serious problems. I need answers of following questions to answer your question: 1) Does your plater provide you coating of black zinc metal or black zinc-cobalt alloy? 2) Does he plate your jobs by electroless nickel ?

Thanks,

Hiren pathak
electroplating - Baroda, Gujarat, India
2003