MikeCochara

Re: Who wants to talk Electropolishing?

I am always interested in speaking to others about Electropolish.  My company is small and we have limited capabilities regarding Electropolishing but that doesn't mean we don't like to learn and try new things.  Does anybody know of a site with information regarding tips and tricks and maybe some techniques?  I'd be happy to share any information I have that may be of help to someone if anyone out there has a question or two.

Mike

zurv

Re: Who wants to talk Electropolishing?

Mike,

Well we hope in the future this will be the site for tips and tricks related to all areas of metal finishing. I am not sure of any other sites were you could find the information your looking for. The reason this site was started was to create a meeting place for these kinds of things. You could try www.finishing.com, there site is full of all kinds of information. A few of their members also partake in our forum. Dont lose ineterest, more will be comming soon!!

Were happy that youve joined us and I hope to see you taking part in our community and sharing your knowlege.

Griffe Youngleson

http://www.zurv.com/Email_Footer.jpg
Visit us on the web at:
www.zurv.com

finishingmarket.com

Re: Who wants to talk Electropolishing?

[color="DarkSlateBlue"]"4"[/color]

Adrienne

Re: Who wants to talk Electropolishing?

[color="DarkOrange"]"3"[/color]

johnthepolisher

Re: Who wants to talk Electropolishing?

I have been polishing & buffing metal "the old fashion way" since 1988. After reading about electropolishing, I decided to buy a small 5 gallon electropolishing kit to see if I could reduce the amount of time buffing stainless steel and aluminum. I fired up the new "system" for the first time today.

The instructions told me to "break in the tank" before processing my first piece. This was done by polishing a piece of scrap aluminum for 8 hours at .8 amps per square inch at 10 volts. The result was a totally dull finish except for some black burn marks where the wire was touching the part. I hope that is what it was supposed to look like...

I have a nagging feeling that I will be visiting this forum quite often...

metfinoh

Re: Who wants to talk Electropolishing?

Are  you sure you have a solution that is suitable for Al??  Most EP solutions are for SS only.  Breaking in the solution is the same as "seeding" the solution which is really all about the metal content in the bath and can be measured in Specific Gravity.  There is tons of info online about EP.  You should check out the website for Metal Coating Process Corporation for starters.

Good luck.

johnthepolisher

Re: Who wants to talk Electropolishing?

According to the manufacturer, the solution is supposed to work for both aluminum & stainless. I have only tried a couple of pieces of aluminum, with less than satisfactory results. The tank temperatures are not getting hot enough with the heaters that were sent with the kit - which could be part of the problem...

Thanks for the link - I have been "googling" like a mad man, trying to find info on EP!

johnthepolisher

Re: Who wants to talk Electropolishing?

How important are tank temperatures for processing different metals? I don't plan on deviating from the instructions, but I do wonder how temperature effects electropolishing, and why it effects electropolishing. This question is purely out of curiosity...

Carolina Process Control

Re: Who wants to talk Electropolishing?

John,

Always remember there are three things that can effect any process bath....

Time
Temperature
Concentration

[url="http://www.carolinaprocesscontrol.com/index.php"]
http://www.carolinaprocesscontrol.com/i/t/logo.png[/url]

DustinGebhardt

Re: Who wants to talk Electropolishing?

Temperatures in an e-polish bath can drastically affect the work being produced.  Depending upon the bath and base metal, high/low temps could cause uneven polishing, preferential dissolving of corner (rounding of sharp edges), pitting (especially true of alloys and aluminum), or a reduction in polishing rate among other things.  And the manufacturing process for the part also plays a role, as forgings act differently than casting, which are different from stampings.

In many manufacturing processes, the edges of the piece are under more internal stress than elsewhere on the part.  This makes them more susceptible to attack by the e-polish.  Normally, the e-polish chemical is designed to take that into account and it tries not to attack those areas by using inhibitors and other things.  However, when you change the temp, you change the way the different parts of the bath work together and their respective rates of reaction.  Now, corners may get attacked faster, which would round them off.

Machined castings and alloys are also notorious for having a microscopic non-homogenous structure.  Under a mid to high power microscope, the structure of the alloy becomes apparent as you can differentiate one metal from the other.  In castings, often the surface of the part is slightly different than the internal areas, and you expose the internal areas when you machine the casting.  Again, changing the temps can cause the e-polish chemical to preferentially go after one part of the alloy, which could cause pitting and other defects.

Stay within the vendors range and you should be okay.  And make sure you know what material you are dealing with.  One person's aluminum may be night and day different from the next guys.  I've seen a few e-polish job shops that struggle with this on a daily basis.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

johnthepolisher

Re: Who wants to talk Electropolishing?

Is it possible to "mask" an area that you don't want to e-polish? For instance, if a customer requests that a certain surface should remain unpolished, is it possible to protect that area from the polishing solution? We have done this on chrome plated parts with aluminum tape, or in certain situations applying a thin coat of paint.

DustinGebhardt

Re: Who wants to talk Electropolishing?

Yes.  You can use special tapes or paints to mask the area you don't want polished.  Just be aware that the e-polish process removes some of the surface material, and you may be left with a noticable raised unpolished surface.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

johnthepolisher

Re: Who wants to talk Electropolishing?

Typically, the areas that I have to mask have serial numbers stamped into the parts - so the raised & unfinished surface is exactly what I am looking for.

You wouldn't happen to know of a good supplier of masking materials, would you?

DustinGebhardt

Re: Who wants to talk Electropolishing?

I've always used the products of Tolber.  They have a whole slew of distributors in the US, my favorite being my former employers out in TX, A Brite.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer

Moen

Sanford, NC

johnthepolisher

Re: Who wants to talk Electropolishing?

Thanks for the info Dustin... Sorry for the delayed response, but I had to manually polish a bunch of parts to keep my cash flow positive (you can check out a couple of recent pieces in the polishing forum).

Since my last post, I purchased a small heater which heats the tanks to the recommended temperatures. But, I'm still not able to polish anything - which I believe is due to my power source...

As per the instructions which came with the set up, I bought a Lincoln Electric AC/DC 225/125 stick welder. I reduced the voltage by wiring the welder to 110v with a dimmer switch on one line (to further reduce the voltage to 10 - 15 volts). I installed an amp meter shunt between the bus bar and the positive power supply. But, according to the amp meter, I can only generate around 5 amps - even with the welder cranked up to the highest setting. According to the ohm meter, I have the correct voltage. Now I'm wondering if the amp meter is junk, or if I hooked up the power source incorrectly... I have to admit that I am getting quite frustrated - the whole process seems fairly basic and easy to understand, but I can't get "Frankenstien" off the operating table...

If I can get this sucker to work, I will be more than happy to invest in a real rectifier to replace the welder. But, I don't want to throw another couple of thousand of dollars into this process without seeing some results.

Any insight would be greatly appreciated...

Tim

Re: Who wants to talk Electropolishing?

We have been kicking around the idea of using electro and/or chemical polishing to eliminate some of our mechanical polishing. Can anyone refer me to some quality products for polishing aluminum and stainless?