Electro cleaning of stainless steel

[gordon stephenson]

But welding cable is multi stranded fine copper with a thin tin coating, Unless the tin could effect the process, Nothing that could rust involved.

 

[Paul.]

I think a welding cable will pass too much current, it will just dead short the power supply, the proper bushes are carbon fibre,

 

[the black box]

Can anyone link to a power supply and the acid required for this process. Got a few stainless jobs coming up and this is so much better than picking paste!

 

[Richard.]

I can’t answer any of those questions as I’m not an expert in this.
I just threw together what Hugh had previously tried and it works spot on.
I don’t know why you’d want to use the copper wire when the carbon brushes are so cheap.
One thing I will say you’ll need some insulation on whatever you use (carbon brush inc) because it gets rather warm after some use

 

[Richard.]

Can anyone link to a power supply and the acid required for this process. Got a few stainless jobs coming up and this is so much better than picking paste!

Power supply 12-24v 4-5 amps
Solution is described in my first post.
Positive terminal on the job
Negative terminal on the brush

 

[the black box]

Power supply 12-24v 4-5 amps
Solution is described in my first post.
Positive terminal on the job
Negative terminal on the brush

Thanks for that will give it a go. Used the commercial units before but for my use they are too expensive (although to electro polish and acid etch is really useful)

 

[gordon stephenson]

I only mentioned the copper cable, after reading and looking at the info shown in post 5, without my spec's and assumed the copper mentioned included the brush it self, Must have just been the connection piece.

 

[Munkul]

where do you get these from, other than ebay?

I buy them for our work, at around £20 each (£95+VAT for pack of 5) which to me seems like an absolute rip-off.

That's the main reason why I've never wanted to rig up my own machine at home.

Ideally I'd find a cheaper supplier for work too - yes they last quite a long time, but it's the principle of the thing...

 

[Munkul]

I passivated my stainless welding cart last night - tried 3 machines using turbo easykleen fluid and a carbon brush holder in a stick electrode holder.

1. Miller XMT - had to use the stick setting since it didn't have an electrode-hot mode in TIG. Min amps 6a. Wayyy too much voltage - violent explosions.
2. Lorch HT200 - stick setting - min amps 10a. Also got explosions etc until I changed the hot start and arc force settings. Worked pretty well after that.
3. Jasic Arc 160 - min amps 10a. Auto hotstart/arc force, too powerful but did work.
- Switched the Jasic to lift-TIG mode and it then worked really well, as well as the isojet 5 that cost £1000 at work

 

[Richard.]

I passivated my stainless welding cart last night - tried 3 machines using turbo easykleen fluid and a carbon brush holder in a stick electrode holder.
1. Miller XMT - had to use the stick setting since it didn't have an electrode-hot mode in TIG. Min amps 6a. Wayyy too much voltage - violent explosions.
2. Lorch HT200 - stick setting - min amps 10a. Also got explosions etc until I changed the hot start and arc force settings. Worked pretty well after that.
3. Jasic Arc 160 - min amps 10a. Auto hotstart/arc force, too powerful but did work.
- Switched the Jasic to lift-TIG mode and it then worked really well, as well as the isojet 5 that cost £1000 at work

The Fixed voltage is way too high in stick mode. You don’t need anything more than 12-24 volts and single digit amps. A
Tig voltage is much lower and probably more suitable to do this.
Not sure how it would feel been used consistently in dead short mind. I’d imagine it’s the same as just sticking your tungsten straight to the bench and keeping the power on. I wouldn’t do this with your lorch if I was you as it might have infringements on your warranty.

 

[hotponyshoes]

Would a tig welder see this as a dead short though?
If the brush is wet (and presumably carbon has some resistance) and the cleaning action must use some current it cant be any different to tigging at 5amps can it?

The copper part of the brush touching would be a dead short but no different to touching down with a tungsten although a tungsten may have much higher resistance than copper.
Some tigs have an anti-stick feature which cuts power if this happens so might be ok?

Not something I would try with any of my welders I hasten to add!

 

[Richard.]

Would a tig welder see this as a dead short though?
If the brush is wet (and presumably carbon has some resistance) and the cleaning action must use some current it cant be any different to tigging at 5amps can it?

The copper part of the brush touching would be a dead short but no different to touching down with a tungsten although a tungsten may have much higher resistance than copper.
Some tigs have an anti-stick feature which cuts power if this happens so might be ok?

Not something I would try with any of my welders I hasten to add!

I honestly don’t know. Your probably right it might be the same and it might be fine.
My concern is other than on the old fronius machines* no body has made a wand that you can just plug into a welder and do this.
Now if they did they would fly off the shelves. So are equipment manufacturers missing a trick or are welding machines just not designed for it?? I couldn’t say.
*the old fuzzys used to have a remote and wand that you plugged into the machine and could passivate stainless. From what I know it was an absolute fortune. Other than that I’ve never seen the integration between welders and cleaning apart from home knock ups.

 

[hotponyshoes]

The homemade versions seem to work pretty well,
I would not risk a tig welder when a power supply is so cheap.

I have a "proper" one made by tec arch. It does not look like much more than a variable transformer in a box but tech arch seem to have a pretty good reputation for quality and value and they are pretty expensive so I presume there is a bit more in there than just that.
Mine uses cleaning pads. I think the pad versions run at lower power than the brushes. I can use a brush but have to turn it up a fair bit.

The pads get pretty dirty quickly - how do you go about removing this dirt when using the brush?
I would use a brush on a tight corner then wipe over the same area with a pad as that seems to pick up a lot more dirt than a cloth/rag.
Wash it all off afterwards.

If using a battery charger or psu with the carbon brush it might be a good idea to fit a fuse or something inline. I have had the crimped points of the copper tack weld itself to the workpiece a couple of times. Not caused any major damage but my supply cuts out pretty quickly and still leaves a small crater in the workpiece which is hard to polish out.

 

[Munkul]

It's not a dead short. It's a carbon brush as Paul alluded to earlier on the thread Richard, with a small degree of resistance. It's electricity running from A to B, same as an Arc, just at a lower voltage (constant current TIG curve at a short - lowers voltage... unless it has an anti-stick mode to boost it? But then you'd feel it)
Even using the Lorch on stick mode, the fan didn't spin up all that much, about the same as it does when stick welding around 100 amps, and the carbon brush never got all that hot... telling me it's not transmitting too much power.

Yes I know stick mode is far from ideal, because of the high OCV and the wrong volt/amp curve... but run at a low enough "arc" voltage, it definitely works. I wish I could have tried the XMT TIG curve.

I see your reason for concern though - it's not quite what the power source was designed for. Given that the Jasic worked better, I'll stick with that anyways, since it's not a £2k power source We also have an old IFL TIG set that we intend to dedicate to the job if it can be repaired.

Elmer Wallace - they make a TIG torch insert. Other than that, I can only imagine it's because purpose-built machines are more lucrative?

What I DO know is that the "purpose built" machines are simply cheap chinese inverters with a HUGE mark-up. The Isojet 5 looks exactly like a cheap inverter without a current control. I bet it cost around £50 to make.

There's still a few fab companies who have never looked at passivation tech and are still using pickling paste... bonkers

 

[Richard.]

Even using the Lorch on stick mode, the fan didn't spin up all that much,

And it won’t because your only pulling minimum current!
No where near the units duty cycle.
My concern is just around the possibility of how it might have an effect on the magic electricicity bobbins internally.
It’s designed to to have an arc gap between the negative terminal and the job. Neither lorch or jasic supply wands for this.
I don’t know enough about them to say it is or isn’t going to have a negative effect and why or where. I’m just saying you might not do it any favours that’s all.

 

[Munkul]

yeah, that's a fair comment

I wonder if some of these unknowns are reasons why passivation companies are reluctant to say "look, you can use your expensive TIG welder as a perfectly good power source!"

Anyways yes, I won't use the Lorch any more

 

[hotponyshoes]

I can take the lid off my proper one if anybody wants to see what's in there?

 

[Richard.]

yeah, that's a fair comment

I wonder if some of these unknowns are reasons why passivation companies are reluctant to say "look, you can use your expensive TIG welder as a perfectly good power source!"

Anyways yes, I won't use the Lorch any more

Fronius did it years ago with the mark 1 magicwave 2000. They had an extra option you could add to the machine called magic clean. It included a remote control, a wand and some solution. I’m guessing it wasn’t a great success as they didn’t carry it on with later models, they built a dedicated machine.
To my knowledge no other company has done it as a professional addition to the set. I’m guessing it just doesn’t really work because like I say I think they would sell very well.

 

[hotponyshoes]

The big one I have has a mig style torch on it. The fluid is pumped out to the tip and the torch has integrated extraction.
Maybe if they are to be sold as professional machines they need to meet safety standards concerning handling of the chemical and fume control?
This might make the cost of adding it to a welding set excessive?
I'm pretty sure tech arc are still selling the basic versions though?

You would think the market for them would be the same size as the people buying welders for stainless work although on an industrial scale one cleaner would probably keep up with 5-6 tig welders working.

Maybe there are other solutions like dipping the whole workpiece in a tank that the bigger companies use?
I wonder if perfect weld setup (robotic etc) needs post treatment anyway?
Every now and again I manage to get a tig weld just right and (at least in terms of colour) it does not look like it needs any clean up at all.
If the weld looks the same colour as the surrounding metal I dont know if there would be any advantages to further processing?