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topic 43547

Start-up of an Electropolishing shop, & some thoughts from viewing another shop

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A discussion started in 2007 but continuing through 2019

2007

Q. I know of a Electropolish Shop near me and has been in and around it for about a year so I have picked up on how the place is run...

They have a 4x8x4 tanks with a P and S acid home mix. There is no prewash tank,they will very often just wipe the parts down or just run them as they come in. After the dip in the polish bath they drag out into a rinse tank, shake the rack in the water then do the same in the next tank and then use a pressure washer to spray water on the parts over the fourth tank. They will either wipe down the parts with alcohol or just air dry and that it. They never really change they bath just decant the rinse waster add that back to the main bath and maybe some more acid. They send out about two to three 50 gallon barrels of waste per year. Now this shop is SOOOO DIRTY! it's shocking! There is junk floating in the tanks, spills all over all the equipment is junk and they are in hot water with the EPA. It seems that everything they do flies in the face of how to electropolish parts or the process. They do a very brisk business since the only other Electro shop in the area went under. So I have decide to start my own shop and set it up right.

One ? I have is, If the parts they are running are being accepted by their customers in such a poorly maintained shop and with all the short cuts and after reading a lot on the proper way to do it, How can they keep running parts when they never replace the acid bath, their tank holds 1000 gallon so to run the shop right won't it cost a lot to dispose of 1000 gallons of waste? It would seem that they parts would not pass for some customers and other don't care as long as the part shines.

Next? would it make sense to set up a shop with two lines, one run like theirs and one for the high end parts? The low end one does more volume and less quality and maybe less charged per part and a high end tank line, charge more less volume but more labor and tank maintenance to get the quality?

One last ?, if you had to start over on setting up your shop, what would you do differently?

Thanks much for your help!

Dan Lewi
- Gresham, Oregon


2007

A. For a start on layout and such, please see my on-line article "Plating Shops for the Nineties and Beyond", Dan.

Electroplating tanks can run in an equilibrium condition and last indefinitely, but electropolishing tanks can't -- any metal that is removed goes into the tank and stays there, either as a dissolved material or as a precipitate. So if they are doing a substantial volume of electropolishing, they are doing substantial replacement of the tank contents whether they run clean or dirty.

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


simultaneous 2007

A. Dan,
Be sure you have a proper building for hazardous materials (H-7 per Fire Code), suitable zoning, and can obtain all necessary permits before investing in any facility upgrades or equipment. Visit the Oregon Department of Environmental Quality's website and local office. Also, the City of Gresham's Department of Environmental Services' Wastewater Services has an Industrial Pretreatment Program -- relevant if you have a sewer connection. Possibly can avoid OSHA by not hiring any employees or using contractors (after hazmats are present).

As for an electropolishing plant: Racking, Soak cleaner, 2 flowing rinses (FR), electropolish, warm DI spray rinse, 2 FR, 30 vol% nitric acid, 2 FR, hot DI rinse, drying & unracking. If using copper racks, unrack prior to the nitric dip. Counterflow all FR, in reverse direction to parts travel -- See 20 Ways to Cut Water Usage in Plating Shops. Forget having two lines -- a needless doubling of some expenses; differences in quality are mostly labor & expertise. You will need more space for chemical storage, pH adjust of FRs, rack storage, RO & DI water system, heating system, etc.

Check financials. Probably, the illegal operator undercut the one complying with EPA, etc., illustrating (Sir Thomas) Gresham's Law: Bad money drives out good. Try to reverse that by compliance with ASTM B912 [link by ed. to spec at TechStreet], 'Standard Specification for Passivation of Stainless Steels Using Electropolishing' and advertising such.

'Infinite life' EP solutions operate at metal saturation -- any additional precipitates as phosphate sludge which must be periodically dredged. Oil contamination occurs even with precleaning, since embedded machining lubricants are released by EP. Skim, filter & add surfactants.

Ken Vlach
- Goleta, California
contributor of the year

Finishing.com honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work
which the finishing world continues to benefit from.



2007

Ted,

So they are keeping the tank in balance by using the drag out solution for make-up in the main tank? But if from what I've read is, that the solutions with a build up of too much iron or metals won't work very well how are they getting by with it?

Also, what do you think of the home made solutions over the factory made ones from electropolishing supply houses, are they worth five times the money?

Thanks very much for your reply?

Dan Lewis
- Portland Oregon


2007

A. I have not seen these 'infinite life' EP solutions that Ken Vlach refers to. My response was posted before I read his; it wasn't intended to contradict him.

If you get invaluable support from the vendor, proprietary solutions can be worth it. If you get no support they are not worth it. The real question is what path can you take to get from where you are to the point where you can do successful electropolishing. Most very small electropolishers buy proprietaries; many if not most large shops use home-brew because they have years of experience and don't need the help. As a startup, you probably do.

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


2007

A. Electropolishing baths traditionally (before the year 2000) would build up metals until they required decanting. The article (Clean, Economical Electropolishing) published in the May 2007 edition of "Products Finishing" demonstrates why this is unnecessary with today's technology. Electropolishing shops have eliminated all acid disposal and many have eliminated all liquid disposal with proper chemistry and filtration implementation.

Regards...

David French
- Charlotte, North Carolina



Electropolishing bath volume is growing

February 18, 2019

Q. Why does the volume of my solution batch of electropolish (sulphuric acid & phosphoric acid) keep increasing above the maximum level of the tank? Is there any reaction occur between those two chemicals?

SITI NADIA
ATC Cleantec, Bangi, Malaysia - Bangi, Selangor, Malaysia


February 2019

A. Hi Siti. There is no reaction between the two acids which causes the solution growth, but concentrated acid like this is very hygroscopic. It absorbs moisture from the air much like desiccants do. The heat of the bath can evaporate some of that water and compensate. What temperature is the bath, and is it kept that temperature 24 hours a day?

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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