Bright V Dull Electroless Nickel

[KENAT]

I've done a little searching but not come to a comprehensive answer so I'm asking for some help.

We currently have a standard note:

ELECTROLESS NICKEL PLATE, .0003-.0005 THICK IN ACCORDANCE WITH SPEC MIL-C-26074 OR EQUIVALENT. DIMENSIONS APPLY AFTER PLATING.

My manufacturing engineering manager just asked that I split the note into 2 flavors for aesthetic reasons.

BRIGHT ELECTROLESS NICKEL PLATE, .0003-.0005 THICK IN ACCORDANCE WITH SPEC MIL-C-26074 OR EQUIVALENT. DIMENSIONS APPLY AFTER PLATING.

DULL ELECTROLESS NICKEL PLATE, .0003-.0005 THICK IN ACCORDANCE WITH SPEC MIL-C-26074 OR EQUIVALENT. DIMENSIONS APPLY AFTER PLATING.

I'm concerned this isn't anywhere near properly specifying the distinction.

(I'm OK with accepting the Mil std listed is obsolete which is why we have the 'or equivalent'. We aren't ISO9001 or anything so that aspect isn't too much of an issue. Although if this directly relates to bright V Dull I'm OK with looking at changing it)

I was thinking ‘bright’ or ‘dull’ would relate to a class, type or grade or something.

Any help on how to more properly specify this is appreciated, thanks.

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[mcgyvr]

The bright/dull surface appearance is not a type/class or anything. Tin plating is the same in that you simply call out bright or dull without a specific class or type associated to that luster/appearance. Ithink the way you have it called out is perfectly acceptable and probably as good as you will get.

 

[IRstuff]

I've been told that bright and dull results in differing amounts of stress. We had a electroless nickel plate that supposedly warped our mirror substrates because the coating was "shiny, and had too much stress.

TTFN

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[KENAT]

Thanks mcgyver, the manufacturing guy says he did some reserach and that was his conclusion, however they tend not to be quite as precise as I like on some stuff so I wanted to verify.

Thanks IRstuff, I saw reference to the stress difference in some info I found. I don't think this will be much of an issue for most of our parts as I can't think of any finer parts that are electroless nickel plated, but I'll flag it just in case. Would I be right in thinking your mirror substrates are relatively delicate?

Just found

http://www.nu-metal.com/dynamicdata/nickelplating.aspx

which mentions one standard, AMS-QQ-N-290, that does categorize bright and dull.

I'm hesitant to change what standard we reference without more research, which I don't seem to have time for, so I'll just use the notes I put in my OP for now.

However, if anyone has anything else to add please do, I can always change it again.

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[IRstuff]

Well, we didn't think they would be; they were sintered magnets about 3/8 inch thick, and we never thought that a few mils of nickel would have sufficient leverage against a much larger substrate, but it did.

TTFN

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[KENAT]

Hmm, interesting. I did bring this up and was told most parts to date have been coming in bright anyway so it shouldn't bee too much of an issue.

However, now that you've said that I may let people know.

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[MagMike]

I'm late to this thread, but I just wanted to mention that I call out mid-phosphorous instead of bright/dull when specifying electroless nickel plating on steel. The phosphorous content plays a major role in brightness and stress levels. Mid-phosphorous usually means 6 to 8%. It's worked well and I've never had a plater call me on it.

As IRStuff mentioned, this doesn't apply to magnets. Nickel plating on magnets is a whole different situation.

Good luck!

 

[KENAT]

Thanks Mike

So just to check, mid phosphorous of 6-8% gets bright or dull, and what do you speck when want the opposite.

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[MagMike]

Hello KENAT, the surface finish turns out semi-bright. Have yet to have a customer complain that it wasn't bright/dull enough for them.

I have to admit, I've never had to spec dull/bright. With mid-phosphorous, the surface finish is cosmetically acceptable but, more importantly, permanent magnets bond well to it. Given the size of the assemblies we make, that's very important.

Mike

 

[KENAT]

I think the issue we have is that for cosmetic reasons sometimes we want dull, and sometimes bright, which is why we were looking at splitting the notes.

We aren't just looking for consistency but actually for 2 cosmetically different finishes.

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[mcgyvr]

Call out Low-Phos for bright.
Mid phos for semi-bright.
High phos for dull.

But it still won't matter because there is no standard for how bright or how dull.

If cosmetic is a real concern the ONLY way to achieve similar results from plater to plater or batch to batch is to provide them with a sample and tell them to match that each time.
We do the same for anodizing. There isn't a spec or time we can call out for how long it sits in the caustic etch bath because even the same bath will produce different results day to day. But we provide a sample and get very similar results from one vendor to another.

 

[coatingengineer]

Hi. I agree with all. Though you may have to look harder for low-phosphorous auto-catalytic nickel. Have you considered changes in surface finish (prior to plating)? Even within mid-phosphorous, you can see differences in appearance between polished or machined finishes, and those that have been lightly grit blasted. Avoid black coloring options through acid etch. They're superficial and not very uniform. Consider, too, shelf like. Electroless nickel ages with time, and that surface oxidation will change its appearance.

William Gunnar

http://www.IndustrialCoatingsWorld.com

 

[KENAT]

Thanks coatingengineer. I believe the first thing we did when we looked at this was to investigate the effect of material finish - and determined that even tieing this down didn't address the issue completely.

mcgyvr, I agree on the sample idea and had suggested this in similar situations with other finishes, but I don't think they're organized enough to really pull it off or something.

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