Summary for activation of mid-phos electroless nickel Discussion
Activation of mid-phos electroless nickel is discussed in the context of chrome plating large shafts that show adhesion problems only at a couple of spots on both ends. David M. Weaver asks whether current robbers at the shaft ends could rob enough current at the start of the cycle to make the electroless nickel go passive before the strike, and whether robber placement too close to the ends might be contributing. He also asks for activation-cycle ideas and current-robbing advice for shafts and rolls. The only reply in the excerpt does not diagnose the problem; instead, the responder asks for more process details before offering advice, including the hard chrome bath type, tank depth, vertical or horizontal orientation, anode length and whether the anodes are cored, filtration/movement, solution level relative to the shafts, and the exact chemical activation process. The thread therefore points to process-specific troubleshooting rather than a single confirmed fix.
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.
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
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.