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


Visit us on the web at:
www.zurv.com

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

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.

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...

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.

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.

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.