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Preparation of Stainless Steel Prior to Electro Polish

We are a designer and manufacturer of Industrial Stairs, Handrails, Platforms, etc. We have recently been asked to Electro Polish a Type 304 Platform consisting of Flat Bar & Square Tube Construction. Should we start with a #4 or 180 Grit Polish prior to Electro Plating, or will a Mill Finish suffice?

Thank you in advance

Patrick Curry
- East Stroudsburg, Pennsylvania
2005

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No one can answer this question without knowing what end requirements you have to meet, and where you are starting from. Your question is about equivalent to asking how do I get to some destination from starting place - you'll have to be more specific, ie, how do I get from NY to LA.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005

Yes, I understand that this is a very broad question. The end product will be used in a Class 10,000 Clean Room of a vaccine manufacturer, so perhaps my first question should have been a recommendation of a final RA and then what finish to start with. Does this help?

Patrick Curry
- East Stroudsburg, Pennsylvania
2005

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To avoid an expensive misunderstanding with your customer, you should ask them to give you a detailed specification for the final finish. This could be verbal, with or without Ra numbers, or, even better, it could be actual samples.

We have electropolished much pharmeceutical equipment, and there is some difference between what one customer wants from another. In general, I would say that you should polish to about 20 Ra, and then electropolish. This will give you a bright, not quite mirror finish, free from mill and handling marks. A #3 or #4 finish is much too coarse (150 or 180 grit) and the abrasive scratches will show after electropolish. You will probably have to go through several steps of coarse to fine abrasive, ending up with 240 or 320 grit prior to electropolish. Use an electropolisher who is familiar with pharmeceutical work.

Let me know if I can help further.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2005