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topic 5791

Hard Chrome Coverage Problem


(2000)

I am having a problem with a hard chrome plating application. We regularly plate hard chrome on molding equipment for production of computer monitors. However, recently we have run into a new "flat" panel design that is causing a problem. The mold plates around the periphery but nothing in the center (like a picture frame). We have tried increasing plating / reversing amps, plating / reversing time, additional anodes, etc... with no luck. The new part is slightly thicker than a standard part, however, not significantly different. We are still able to plate all of our other parts, just a problem with this one. We also tried new hangers to no avail. Even went as far as to change the rectifier on our reversing tank (we reverse in a separate tank than we plate, for non-contamination purposes). Amps at the plating tank are good (around 2300 A for this part). Our substrate preparation is very thorough and the same for sizes other than this new design. Any ideas on what to try? An! y advice is much appreciated.

Steve Clark
- Waymart, PA -- USA


(2000)

HI! STEVE ,

Try an under coat of Electroless nickel of 10-12 microns and the transfer the mould in the hard chrome plating tank after proper Rinsing with current applied as the mould is dipped in the tank at usual C.D that you are applying to normal moulds the problem will be solved.

MAHENDRA GARGATTI
ELECTROPLATERS - Belgaum INDIA


(2000)

HI STEVE,

WE'VE BEEN DOING MOLD PLATING FOR 10 YEARS WITH ELECTROLESS NICKEL,HARD CHROME AND BRUSH PLATING AND HAVE HAD ALL KIND OF SITUATIONS.

WE HAD SIMILAR PROBLEM WITH DEEP CAVITY MOLD INSERTS FOR COSMETIC FACE CREAM MOLDS SIX MONTHS AGO. THE 24 CAVITIES WERE 3" IN DIA. X 3" DEEP. WE SUGGESTED THE CUSTOMER TO CHANGE TO ELECTROLESS NICKEL BUT THEY WANTED HARD CHROME. SO WE KEPT TRYING UNTIL SUCCESS CAME BY USING A CONFORMING LEAD ANODE THAT WAS 1/4" APART FROM EVERY SURFACE AND AN UNUSUALLY HIGH AMPERAGE OF SOME 30AMPS PER SQ.IN. WITH A FLUORIDE CONCENTRATED CHROME BATH AT 52 DEG. CELSIUS FOR 5 SECONDS REVERSE AND JUST 3 MINUTES PLATING TIME. THE CHROME COVERED BEAUTIFULLY THE WHOLE SURFACES ONLY THAT IT CAME OUT DULL. A FINAL POLISH WITH EMERY PAPER MESH 1200 FIXED THIS.IF YOU STILL NEED HELP, WE'LL GIVE IT FREE ON THIS SITE.

G.MARRUFO

Guillermo Marrufo
Monterrey, NL, Mexico


(2000)

Thank you for your generosity in providing such a concise and detailed response, Mr. Marrufo!

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



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