Letter 22028

Machined Surface Value Mystery  

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Hello.

My company has recently begun importing finished components for our customer's stocking programs. We are not overly familiar on measuring surface finishes and the values and formulas that are used. Your site came up when I searched for "surface finishing". We are trying to find some basic data on RMS, RA and "microinch" values and how they are measured and/or converted back and forth. Can you recommend how we could find this information? Please understand, we will not do any actual measuring, but want to better understand the terminology and values. Thanks for your help.

Regards,

Sean O'Boyle
- Houston, Texas, USA

Normally I try to answer questions directly; however, for this subject, I think you maybe better off going to one or both of the following websites: http://qualitymag.com/articles/2001/aug01/0801F1.asp and http://www.predev.com/smg/parameters.htm

AF Kenton Nova Finishing Systems Inc. Huntingdon Valley, PA

Sean, ASME offers a superb book on the topic. It's ANSI/ASME B46.1 [link is to spec at TechStreet], on Surface Texture (Surface Roughness, Waviness, and Lay). You can find out more on the ASME web site.

Lee Gearhart metallurgist East Aurora, NY

Answer or follow-up on this subject (in non-commercial fashion).

 

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