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Inside of beaker shaped part is not Electro Polishing

A beaker [beakers on eBay or Amazon [affil links] with thickness 1 mm, and inner diameter is 47 mm, height is 155mm made-up of ss316, when I tried for electropolishing, the inner part of the beaker is not getting polishing well, could you suggest me how electropolish evenly in outer and inner part of beaker.

Vijay K
Production Manager - Coimbatore, Tamil Nadu, India
March 25, 2009

Ed. note: oops! Editor's error in title of this letter.

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First of two simultaneous responses -- April 1, 2009

Hi Vijay,

The cause is that most of the current flows to the outside and there is insufficient current density in the inside to support electropolishing.
The first step is to ensure that the open end of the beaker is facing the cathode and that the opening is not obstructed by the rack. Lowering the temperature will also help. These steps may be sufficient in marginal cases, but more usually only results in the electropolishing penetrating a little further down the inside.

There are two more effective, though less convenient steps.
1) Introduce an internal cathode into the inside of the beaker. This will have physically but not electrically connected to the rack in order to locate it accurately.
2) use some non conducting material (e.g. plastic) to form a partial shield to reduce the current flow to the outside.
Consider using both.

Is this of help?

Harry Parkes
- Birmingham, UK

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Second of two simultaneous responses --

Use an internal cathode. The current density inside the beaker is too low and unless you are careful, you will etch the stainless steel. using an internal cathode will allow you to increase the cd on the inner surface and get polishing

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
April 2, 2009

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May 7, 2009

Hi Vijay,
if you are using an Axillary Anode for Cleaning it may solve your problem.

you need to keep a separate anode inside the flask. or keep a rod with anode connection. it may help.

Kannan Boopathi
- Salem, Tamil Nadu