The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Electropolishing Problems and Corrections

Hello,

I am trying to solve an electropolishing problem with T304SS items (kitchenware, cutlery items). I am experiencing random problems with electroplating items, wherein some of the items come out with a "waviness" surface or "etched" edges.

Other Question: How can I lower the concentration of Loose ions of iron (or nickel) left in the bath of electropolishing plant of s.s. objects? [Bath composition :H2SO4:H3PO4 ;1:2.] and the last question: How can I protect the racks (copper alloy) against electrochemical corrosion?

Truly yours,

Ebrahimi,Alireza
polishing co. - Isfahan, Iran

---

 

I think I can help you with your problems but it would be better if I had more information.

How many parts are you running at a time? What size and shape are the parts? How are you racking them? What temperature are you operating at? How long are you running them? What is the surface finish before electro-polishing? How long do you polish them? What is the iron concentration in your bath? How many amps are you putting into your bath? Getting good results with forks is difficult between the tines but it can be done.

As for the protection of your racks there are a number of things that you can do. Titanium clad copper is an excellent solution to the problem. If this is not possible for you then you could try coating your racks with Plastisol. Even coated racks will not last for ever but they will reduce the amount of copper that finds its way into your bath. Racks made of titanium have great life but have poor conductivity and are not usually suitable except for small parts. That is why I suggest titanium cladding.

Reducing the iron in your bath is difficult and it is the iron concentration that usually defines the endpoint of the useful life of the bath. If any other reader knows of a cost effective solution to this problem then I would be interested to hear it myself.

John Holroyd
- Elkhorn, Wisconsin