Joe Diemer

Topic: Polishing Stainless Without the EPA Possible?

Hello Finishing Talk Members,

I manufacture custom birdcages for the exotic bird market. In the past I've used mild steel and finished by bead blasting and then powdercoating. I'd like to offer the product in stainless, but cannot find an appropriate inhouse finishing system to remove the oxides from the brazing process.

These cages are large - the size of an 85 gallon drum and larger, and have hundreds of cross-wire welds. So obviously hand polishing is out. Bead blasting the joints leaves a satin finish that is too time consuming to polish. They are too large to tumble. An immersion process would be the way to go, but ultrasonics in citric acid only removes about 50 - 60 % of the oxides.

Electropolishing seems perfect, but I'd like to avoid serious mineral acids like hydrofluoric and nitric due to the sheer amount necessary, and the desire to keep the EPA and board of health away from our shop. Looks like we've hit a brick wall! Any ideas, info, or websites to check out would sure be appreciated!



   BC1.jpg
   BC2.jpg

www.handmadebirdcages.com

skip

Re: Polishing Stainless Without the EPA Possible?

Joe Diemer, From my previous post. I don't think the EPA knows or even cares about this inhouse process used in the welding department.

Hatco Foodmachine Company in Sturgeon Bay-factory/Milwaukee-office cleans weld stain and smoke from stainless steel weldments of welded cross wires and folded cornor joints to produce drip pans for food warmers with an acid compound that I have no knowledge of. But watched this being done.

Using a wood tounge depressor and a wire down it's length from a transformer and buried in a piece of cotton rag...this cotton is dipped into a cap full of solution and placed on the stain. Moments later the stain is gone and the area is spounged with warm water padded dry.

So dab on the acid, asap touch the stain with the wand and presto. Weld stain on the stainless steel is gone.

The gals doing the job just use rubber gloves, and an splash plastic apron and safety glasses. No respirator required. After the touch the area is padded dry.

Maybe something can be made out of that. I wish I could be more help.

skip.

Last edited by skip (12/23/2009 - 01:21 PM)

Your Best Finish Starts Here

DustinGebhardt

Re: Polishing Stainless Without the EPA Possible?

I know of a shop that uses the same principal that Skip describes, but on a much larger scale. Electropolishing can be done with a wand, especially when all you want is the clear up the weld stain. Most e-polishes uses some sort of acid and perhaps peroxide, but tend to be much more user (and EPA) friendly than non-electrical chemical polishes. Contact your local metal finishing vendor for more info. If you are in the USA, I can send you some contact info for some top-notch metal finishing supplies vendor.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

Joe Diemer

Re: Polishing Stainless Without the EPA Possible?

Hey guys, thanks for the replies. Skip, you're probably right about the EPA knowing or caring about my operation - I might have been flattering myself. The magic wand method sounds interesting, but I'm going to keep pursuing an immersion method due to the quantity and geometry of the joints.

I'm trying to remove gooey flux residue, black braze oxides, and mild heat tint. The citric acid in ultrasonics removed all but some of the oxides, and left a "frost" wherever flux was.

Just for kicks I gave some samples to the big local finisher here in Portland Oregon to see what the heavy duty acids could do. They came back in bad shape. More of the braze oxides were removed (80%), but all of the 304L was greyed. The silver braze alloy was dead grey also. Strangely the 316L looked great, except it too was greyed where the flux had been.

I'm surprised that I continue getting samples returned that are obviously unusable. There must be some dipping process for a reasonable cleaning of silver brazed stainless steel. I'm still trying to avoid the large vats of steaming acids if possible - seeing as how this is a family business and a couple of our members tend to be experimental.

I've been getting info on electropolishing, but they never say just what exactly the electrolytic solution is composed of. They do mention Nitric in the pre and post cleaning tho, but I hope there's another way.

Hey Dustin, I'll take that info on your vendor. Thanks for your help.

Our shop address is:

408 SE 6th Ave
Portland, OR 97214

www.handmadebirdcages.com

Joe Diemer

Re: Polishing Stainless Without the EPA Possible?

Here's an update:

The vendor didn't work out. He said:

"Honestly I don't know of anyone that can help you on that type of budget (10 - 40K). As I mentioned we specialize in small companies while all of our competitors will not deal with you unless you commit to spend $250K or more with them."

I had samples electropolished at two different places and they both came back with the silver solder dead grey. So if anybody knows of a dipping process for a reasonable polishing (or at least cleaning) of silver brazed stainless steel let me know. Thanks in advance...

www.handmadebirdcages.com

russamer

Re: Polishing Stainless Without the EPA Possible?

The silver solder will always be a problem. However if you switch to a regular welding for stainless steel you can easily electropolish such cage in our Universal electrolyte. When installing Universal tank at Techmetals we tested welded parts - they come perfect out of electropolishing without special pretreatment.

Since this electrolyte is eco-friendly (no fumes, no sulfuric acid), it can be used in small shops without EPA problems. Besides it can be used for electropolishing all kinds of stainless and even high-carbon alloys, brass, copper, aluminum, nickel - can also be electropolished in the same tank. I think you can fit into 10K-40K budget.

Anna Berkovich
Russamer Lab

Joe Diemer

Re: Polishing Stainless Without the EPA Possible?

Thanks, but I'm going to continue silver brazing as it makes the smoothest joint.  This way birds claws don't get trapped, and it looks really nice.  Please keep me in mind if anybody has ideas!  If you want to see close up pictures of the cages, go to:

www.handmadebirdcages.com

www.handmadebirdcages.com

Tonzze

Re: Polishing Stainless Without the EPA Possible?

Hi, Joe,

Maybe you can have a try at vibratory polishing machine. I think that machine is workabel for your cages.


Attachments:

  Products Catalog.pdf

Jeddy Huang

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Deburring & Polishing Machine

http://www.tonzze.cn

Joe Diemer

Re: Polishing Stainless Without the EPA Possible?

Hi Jeddy,

Thanks for the catalog, but I think the cages are too large for a donut-shaped vibratory polishing machine.  They are the size of a 55 gallon drum.  Is there something else you're referring to?

A while back I tested one in an enormous tumbler filled with ceramic media. It got the cage perfectly clean and moderately reflective but distorted it in the process.  Also, the hourly rate to use the tumbler was prohibitively expensive.

--Joe

www.handmadebirdcages.com

hebeihaituo

Re: Polishing Stainless Without the EPA Possible?

Hi joe,
In fact you can also see if can use ultrasonic polishing try? If you are interested in, can see here:
http://www.hbhtkj.com/en_index.asp