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Activation of mid-phos electroless nickel

1998

We are plating large shafts with chrome over mid-phos electroless nickel. We mechanically and chemically activate the part and get excellent adhesion except for a couple of spots on both ends of the shaft. I'm fairly confident in our activation cycle, but I'm concerned about the current robbers placed on both ends. Will the current rob the ends enough in the beginning of the plating cycle to cause the EN to become passive prior to the strike cycle? Would the orientation of the current robber play a role in this problem. I.E. too close to the end of the shaft. We are plating chrome on the EN shaft within a couple of hours.

Any activation cycles would be appreciated. Current robbing expertise on shafts/rolls would be appreciated as well.

Thanks,

David M. Weaver [deceased]
- Toccoa, Georgia

Ed. note: With great sadness we must advise that David passed awayt on Aug. 15, 2003.

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1998

? Dear Dave ,
Can you provide a little more info please such as :-
1 ) Type of Hard Chrome Solution ( HEEF or otherwise , if otherwise please specify & supply analysis of solution )
2 ) How deep is your tank ?
3 ) Are the shafts plated vertically ?
4 ) How long are your anodes ?
5 ) Are your anodes "Cored"
6 ) Do you use solution movement via filtration what sort of set up and at what rate ?
7 ) Distance from Top of solution to the top of the shafts being plated ?
8 ) provide exact details of your chemical activation process

regards

John Tenison - Woods
- Victoria Australia

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1998

Tank Size: 12 Foot deep, 36" Diameter
Part Size: 110"
Vertical Orientation
HEEF Chrome
Filtration: Mechanical Agitation (rate:unknown)
Activation: Mechanical (pummice) Chemical(Nickel Activator)
The anodes I am unsure (what are the different types.
The end of the shaft is about 2 feet from the surface of the solution.
We enter the solution Live. about 3volts or so. running about 4200 amps.

David M. Weaver [deceased]
- Toccoa, Georgia

Ed. note: With great sadness we must advise that David passed awayt on Aug. 15, 2003.

P.S.: I have now figured out my problem, Thank you for your responses.