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Residue on electroless nickel parts after drying

 

Hi,

I'm the Assistant Production Manager in a small Scottish engineering company. At present we turn and grind mainly mild steel shafts which are then electroless nickel plated. The thickness of the plate is normally between 0-20 microns dependent on the customer requirements. We present the shafts to the solutions in stainless steel jigs (nominally 250 shafts per jig) and dry in a non circulating oven. The problem is that a high percentage of the shafts end up with jig marks at the contact points with the shafts or water marks along the diameter of the shaft. It is the company's belief that this is mainly due to the oven not drying the residue off the shafts quickly enough.

Can anyone confirm or rebuke the consensus of opinion here?

Eddie Moore
- Paisley, Renfrewshire, Scotland

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Hi Eddie. The old joke goes: "How many computer programmers does it take to change a light bulb?" "None, they adjust the software". The silly part of course is that you should really fix a light bulb by fixing the lightbulb not by adjusting something else. The applicability to your question is that if you have objectionable jig marks, you might better focus on the jigging method, than on adjusting the electroless plating solution or the oven to accommodate the problematical jigging. As for the water marks, usually they are not actually caused by water but by the dissolved salts in the water. It is usually necessary to rinse in de-ionized water, or to use some drying aid like alcohol, solvent, etc. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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These jig marks, are they rust colored? Are the water marks white hard-water deposits? Have you tried clean rinsewater? Have you tried to blow the parts dry using clean compressed air, after a hot deionized dip?

  
Tom Pullizzi
Falls Township, Pennsylvania
 

But of course! There are residues that are simply not dryable (they are as dry as they can be). Also, if you contact any surface that is to be immersed for plating or anything else, you are impeding the liquid to get to that point.

Guillermo Marrufo
Monterrey, NL, Mexico