Letter 11025

Ra Values and Description 

I AM LOOKING FOR SOME GUIDE RELATING Ra VALUES TO DESCRIPTIONS LIKE MIRROR FINISH, SATIN FINISH ETC.

Samuel Tai
- Singapore

You are probably aware of the fact that the lower the Ra or RMS number, the finer the surface finish profile. Now, these number do not and can not relate to texture, such as a satin finish etc, because you are talking about a reflective or optical quality of a surface. I other words, you can have a relatively bright appearance on a part with a 120 Ra or lower and I can also achieve a satin finish on these same Ra values. These are 2 different unrelated standards of measurement.

AF Kenton Nova Finishing Systems Inc. Huntingdon Valley, PA

Hello Samuel!

You really want to take advantage of the information that the Nickel Development Institute has published on this. Go to http://www.euro-inox.org/e/material/arch/Cochrane_e.pdf and enjoy the informative article.

Good luck!

Lee Gearhart metallurgist East Aurora, NY

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