What are the tolerances for surface finishes between Machined surface symbol and Basic surface symbol. ???
Surface Finish are typically a not to exceed specification unless otherwise specified. For example, Ra 32 means that the surface finish shall not be rougher than 32 microinches Ra.
One can specify a range with the surface finish symbol or within an associated note.
For basic 32 Ra finish, i was told it has a 16 rms variance. Then the Machined finish (Closed check-mark finish) has a tighter tolerance. What we are trying to do is justify why one is better than the other for inspection purposes.
wanting to use the symbol with loser tolerance.
Last edited by belinda63; 01-12-2015 at 04:01 PM.
Is this an internal standard or requirement?Originally Posted by belinda63
The surface texture/finish standard is ASME B46.1-2009. I do not believe that "a 16 rms variance" is a requirement in the standard. If I'm mistaken please advise me where in the standard I can review this requirement.
Not according to the standard .. This symbology means that material removal is required to achieve the end size. The tolerance and end item size or form is normally included with the limit tolerance associated with the feature though preceding the closed check mark with a nominal number will indicate that this is the amount of material requiring removal. Again there is not a tolerance unless it is specified with the nominal value or included in a note.
Thank you Kelly, I have taken classes from you for many years and completely trust what you say. I apparently was misinformed from SLB Engineer.
Thank you for always being there.
Don't get me in trouble with anybody I know! BTW, If the engineer is your boss ---- they are right..
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