# Welding A Part With A Plating?



## Skowinski (Nov 12, 2020)

Ok, I'm wanting to make a tool for holding the splined shaft on my PM-833TV.  I found this coupler (made for water pump connections between motor and shaft) that will work, but I need to weld a handle onto it.  It's some sort of magnetic steel, with what appears to be a coating?  Or has it been heat treated?  It's just a dull grey inside, but the outside is a golden color with some reds and greens in it in the right light. 

Don't want to fire up the welder and gas myself out if it's a coating I'm not aware of....

edit: no information about this on the website where I ordered it from.


----------



## Flyinfool (Nov 12, 2020)

That looks a lot like cadmium plating, a great rust preventer. Welding thru cadmium will produce highly toxic fumes and dust. Do it outside and make sure the fumes are blowing away from you.


----------



## Skowinski (Nov 12, 2020)

Flyinfool said:


> That looks a lot like cadmium plating, a great rust preventer. Welding thru cadmium will produce highly toxic fumes and dust. Do it outside and make sure the fumes are blowing away from you.



Thanks.  Hadn't thought of cadmium.... only really familiar with zinc and chrome plating.

Yeah, it was the fumes I was worried about, but I think the welding on this part can be done in less than 30 seconds max, maybe 15.


----------



## DavidR8 (Nov 12, 2020)

I don't know if it will work for Cadmium but a soak in pickling vinegar makes quick work of galvanizing. Worth a try...


----------



## Flyinfool (Nov 12, 2020)

Skowinski said:


> Thanks.  Hadn't thought of cadmium.... only really familiar with zinc and chrome plating.
> 
> Yeah, it was the fumes I was worried about, but I think the welding on this part can be done in less than 30 seconds max, maybe 15.



The issue is that the toxic dust will still settle everywhere, Do it outside.
The cad will also contaminate the weld and weaken it.

The chemical used to remove cad plate is ammonium nitrate. I do not know the specific process.


----------



## Skowinski (Nov 12, 2020)

I suppose I could also take it outside and hit it with a steel brush on a grinder to remove the plating on the side I will weld.

Anyway, will definitely do whatever I decide outside, this Cd plating doesn't sound like to good thing to be messing with.


----------



## Nutfarmer (Nov 13, 2020)

Cadmium is a killer. In water line flanges all bolts are black iron because of this . Never flame cut cadmium plates bolts. If you can grind off the plating  go ahead Cadmium can kill you. Not worth the risk.


----------



## Lo-Fi (Nov 13, 2020)

Can you braze or silver solder it rather than weld it? If its some kind of tool steel, it will not take well to welding anyway.


----------



## rwm (Nov 13, 2020)

I think that may just be yellow zinc plating (zinc chromate).
Like this:


 Either way, just have a decent fan blowing continuously to carry the fumes downrange. I have done this many times when casting zinc alloys and it works fine. 
Robert


----------



## Skowinski (Nov 13, 2020)

Uggh... thanks guys.  Whatever it is I don't want to mess with it inside, I'll take all precautions.

edit: it does look a lot like that pic of yellow zinc coating.....


----------



## RJSakowski (Nov 13, 2020)

I first became aware of cadmium poisoning some fifty years ago when working in the battery industry.   Mass cadmium poisoning from industrial waste from mining in Japan made headline news.  The disease was called itai-itai, literally ouch ouch due to severe pain in bones and joints.  As a chemist who dealt with cadmium from batteries on a regular basis, we were understandably concerned.  

Cadmium is a cumulative poison but it is also a naturally occurring element and is consumed daily in amounts of  some 20 -100 µg.  Most of the issues concerning cadmium poisoning  arise from industrial exposure where people are exposed on a long term continuing basis.  

Cadmium electroplating of steel results in coating thicknesses of around 50 microns.  A weld of 1cm width and 10 cm length would release at most around 50 mg of cadmium , mostly as cadmium, oxide.  Unless one made a conscious effort to breathe in all the welding fumes only a very small percentage of cadmium would be inhaled.  Probably no more than the amount one had for breakfast in one's cereal.  

Unless I was welding the material on a daily basis, I wouldn't be concerned about welding a piece of cadmium electroplated steel.  Use the normal common sense approach to dealing with welding fumes in general.

As to the weldability of the spline, it is most likely a medium carbon steel. To be prevent localized cracking, it would be good practice to stress relieve the part after welding.

BTW, the chromate part of zinc chromate is hexavalent chromium. But that's another story.


----------



## pontiac428 (Nov 13, 2020)

It's not cadmium.  It's yellow zinc, like @rwm said.  You won't find cadmium on anything made in the last 30 years unless it's very, very special (think avionics and torpedos).

It will cause your weld to turn to $h!t right before your eyes, so remove the coating before welding.  RJ is right, there is the hex chrome component, so control the dust when removing.   Use an acid soak instead of a powered wire brush.


----------



## Skowinski (Nov 13, 2020)

pontiac428 said:


> It's not cadmium.  It's yellow zinc, like @rwm said.  You won't find cadmium on anything made in the last 30 years unless it's very, very special (think avionics and torpedos).
> 
> It will cause your weld to turn to $h!t right before your eyes, so remove the coating before welding.  RJ is right, there is the hex chrome component, so control the dust when removing.   Use an acid soak instead of a powered wire brush.



Thanks, any recommendations on type of acid to remove this troublesome coating?  Not sure what I can get my hands on now, would have been easier a few years ago when I worked in a university laboratory and could access just about anything, some of it pretty nasty like hydrofluoric acid.

edit: found some information that muriatic acid which is easily found will work


----------



## Skowinski (Nov 13, 2020)

And thanks @RJSakowski for the cadmium lesson!


----------



## RJSakowski (Nov 13, 2020)

Fun Fact.  According to the European Commission, a kg of dark chocolate can contain as much as 800 µg of cadmium.


----------



## Skowinski (Nov 13, 2020)

RJSakowski said:


> Fun Fact.  According to the European Commission, a kg of dark chocolate can contain as much as 800 µg of cadmium.



Damn, glad I don't eat dark chocolate by the kilogram!

Uh oh... better go check on my wife.  

Got the part fizzing happily away in muriatic acid outside, man that is stinky!


----------



## FOMOGO (Nov 13, 2020)

Ahhh!! hence the brand name Cadbury. Mike


----------



## Skowinski (Nov 14, 2020)

Muriatic acid did the trick, about 2 hours in it fizzing away, when the fizzing slowed down I took them out and rinsed thoroughly, then dried in the shop oven at 250F.

Got some flash rust which easily brushed off.  Thanks everyone for the advice!


----------

