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topic 2300

RACK MARKS IN ZINC PLATING


(1998)

WE EXPERIENCE SEVERE RACK MARKS ON LIGHT STAMPINGS FROM OUR LOW CYANIDE ZINC BATH. RE-SURFACING THE RACK TIPS AND /OR ELECTROLESS PLATING THEM HELPS, BUT THE PROBLEM RETURNS IN ABOUT 4 TO 5 WEEKS. THE CHEMISTRY IS CONTROLLED TIGHTLY, AND THE DISTRIBUTION, THROWING POWER, AND EFFICIENCY ARE ALL GOOD. HULL CELLS PLATED AT 0.5 AMPS OR 3.0 AMPS, SHOW NO SIMILAR SIGNS. ORGANICS IE. BRIGHTENER, ARE KEPT TO A MINIMUM. METALLICS SUCH AS Pb AND Cd ARE NON EXISTENT.

ANY IDEAS?

RAY DELOREY
- CAMBRIDGE, ONTARIO,CANADA


(1999)

Ray:

Are the light parts too light? If they are in the bath they may flutter and cause a bi-polar effect. Sometimes they are dark sometimes not. The elctroless plated rack tips may be helping with conductivity and as it wears away the problem returns. You won't see this on the Hull Cell. Generally if I can't duplicate it in the Hull Cell its something on the line or process that is contributing. Try pinch racking one rack of parts and see if this goes away, this will tell you that it is current and that the part is too light. Also if heavier parts plate fine then this would be another indication the parts are too light.

KH

Ken Hutchinson
- Minneapolis, Minnesota



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