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topic 9146

Electropolishing of Brass: solutions, procedures, references



A discussion started in 1998 & continuing through 2017

(1998)

Q. Hi

I have a complex surface that is diamond turned similar to a rotating polygonal multi-facet mirror surface used in supermarket scanners. It is made of brass (I could get one made of aluminum). The diamond turning operation achieves a surface of less than 1 µm rms.I want to improve the finish to less than 0.1 um rms to achieve an optically mirrored finish which I can bounce a laser beam off of at uniform reflectivity.

Can electro-polishing help? What are the limitations? Are there other approaches? What companies can perform such an operation? Note that the surface would be very difficult to hand polish as it is not flat or spherical.

Eric Swanson


(1998)

A. Eric:

In theory, electropolishing can produce about a 50% reduction in the surface RMS. It is important, however, that the diamond instruments used to machine the surface do not smear the metal. It so, you will probably be disappointed with electropolishing, regardless of the metal you use.

I should add that electropolishing of brass and copper is possible; however, the surfaces produced may need to be protected after electropolishing. Aluminum may need anodizing and brass may need chromating or lacquering to prevent corrosion. The post-treatments may affect the mirror quality you are seeking.

Ed Bayha
Metal Coating Process Corporation - Charlotte, North Carolina



(2001)

Q. Hi,

We currently have brass items that need to be polished and clear coated. The polishing takes a long time and is labor intensive. I need to know if there is an electropolishing solution used for brass that is safe to use and low odor if possible.

Any help is appreciated.

Thanks,

Rob Henry
- Cleveland, Ohio


(2001)

A. Rob -

There are chemical polishing systems for brass that are electroless and have low to no odor (also no chromic or nitric acids).

adv.
Our name for our product line is Laser - finishes from matte to high gloss can be achieved.

Dan Brewer
chemical process supplier - Gurnee, Illinois



(2003)

Q. I have a two halves mold made of Naval Brass. In this mold there are slots 0.5 mm wide 1.2 mm deep. these slots are made using EDM technology. Is it feasible to improve surface finish inside the slots using electro polishing? required surface finish is better than 32 r.m.s. Metal removal should be minimal and even.

Best regards,

PINHAS GALLON
Mechanical Gyroscopes - JERUSALEM, ISRAEL


(2003)

Mold Making Handbook

A. I am not sure electropolishing can be used in polishing moulds because of the highly variable local current densities. However, chemical polishing can be done as has been done for some years. I recall a patent from about 1983 that describes a chemical polishing solution for copper and its alloys that uses "bovine vitamin B6", however, I do recall any other details. There is also an article in Transactions of the IMF from 1988 (vol 66 p 18-21) that may help, but that is about tool steels. I suggest you do a literature search and base it around 1975-present.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK



Electropolishing brass ship clocks

(2004)

Q. Dear sir,

As a builder of ship clocks made of Brass I like to electropolish the Brass by my self. How can I do it.

Blessings, ASA

Asa Bentor
- Hod Hshron, Israel



(2004)

Q. Hello...

I want to know how can can I electropolish a brass part? We plate a brass part and sometimes we have to strip it. Then when we replate it, part is being tarnished. So if we polish a brush polish then O.K. But it's very difficult for us. If we find available electropolishing solution it will be very easy for us. I tried some formulas but I couldn't find the right formula. Could you give me a clue, if it's possible? Thanks.

Emre Tuna
Engineering - Istanbul, Center, Turkey



June 28, 2008

Q. I want to ask you that is there any solution for the electropolishing of brass?
I want to know the electrolytic bath for this process of electropolishing?

ABHISHEK GUPTA
STUDENT - DHANBAD, JHARKHAND, INDIA


June 30, 2008

A. Hi, Abhishek. Yes there is. A computerized lit search of a small specialty database (Metal Finishing Information Systems, England) showed seven references. Phosphoric acid seemed to be the most common electrolyte. If you have access to either the Electroplating Engineering Handbook or Tegart's "The Electrolytic and Chemical Polishing of Metals", they will help. Good luck!

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



February 16, 2009 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Dear Sirs,
We are manufacturer of brass chandelier. We polish brass parts mechanically and recently I am researching about electropolishing method.
I tested phosphoric acid and was not successful. Pleas tell me what is the suitable for brass parts
Regards

Mehdi Zomorrodi
product designer - Tehran, Iran
br

February 18, 2009

A. Straight phosphoric does not work well on any metal. Also, you did not mention the amps per square foot or the applied voltage, the tank temp or the time. They are all factors for ELECTROPOLISH.
Talk to some commercial vendors. You may be able to find someone that sells a commercial chemical polish that will work well enough. If not, a commercial electropolish specifically for the type of brass that you are using will be the cheapest in the long run.
For home brew, check out expired patents on the internet for your type of brass.

James Watts
- Navarre, Florida



April 28, 2011

RFQ: Hi, I am looking for electro polishing of my brass parts; can you do it?

Willy Koh
- Singapore
^- Sorry, this RFQ is outdated
     View Current RFQs




November 29, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Our shop is in need of a simple electropolishing setup for small brass parts (stamped). I've heard of citric acid / reverse wiring them up. Tips? Advice? Thanks.

Matt Pisarcik
- Phoenix, Arizona USA

December 11, 2017

Matt,

Brass can be electropolished by Universal Electrolyte.

adv.
Contact me directly for advise.

anna_berkovich
Anna Berkovich
Russamer Labs
supporting advertiser 
Pittsburgh, Pennsylvania
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