When a Part Print specifies 10 Rmax on a Surface - Rmax Settings & Standards?

R

realsteeltools

Example: When a part print specifies 10 Rmax on a surface.
What standard to use JIS, DIN, ISO, MOTIF, CNOMO, ANSI, VDA, ....?

They all seem to give different values on standard test blocks?
 

Jim Wynne

Leader
Admin
Welcome to the Cove. :D

You're referring to (I assume) values expressed on a drawing as Rz or Ra?

There's a good short article on the subject at the Modern Machine Shop website. The last paragraph:

Communication at the outset of the project can avoid most surprises. The approximate, and sometimes questionable, comparisons can be avoided by developing an understanding of exactly what a parameter on a print means, and how the various parties involved in the production plan to check surface texture. The best way for those involved in the production to be in agreement on the parameters for measurement is to have capable evaluation equipment in both the manufacturer's and customer's facility, making the same check using the same method. If the manufacturer or the customer uses conversion ratios, then both parties should be aware of the use of the ratio and be comfortable with the ramifications.

If you're not sure of what the customer expects, especially with something as dicey as surface finish, it's always best to ask and make sure both sides agree on interpretation of specifications and methods of inspection.
 

Kales Veggie

People: The Vital Few
Example: When a part print specifies 10 Rmax on a surface.
What standard to use JIS, DIN, ISO, MOTIF, CNOMO, ANSI, VDA, ....?

They all seem to give different values on standard test blocks?

Yes, Rmax is confusing. Your customer should have the answer. I would not assume in this case.
 
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