Nonmandatory Appendices and Surface Roughness
Nonmandatory Appendices and Surface Roughness
(OP)
Hello,
Does anyone know what the nonmandatory appendices mean at the end of some of the ASME standards? For example, ASME B46.1-2002 has a nonmandatory appendix B. I'm wanting to implement a general note "SURFACE ROUGHNESS SHALL BE 125 MICROINCHES OR BETTER." But someone has discovered this nonmandatory appendix that states "Surface texture should not be controlled on a drawing or specification unless such control is essential to the functional performance or appearance of the product. Unnecessary restrictions may increase production costs and mitigate the emphasis on specifications for important surfaces." The engineer interprets this as not to callout surface roughness at all.
lm
Does anyone know what the nonmandatory appendices mean at the end of some of the ASME standards? For example, ASME B46.1-2002 has a nonmandatory appendix B. I'm wanting to implement a general note "SURFACE ROUGHNESS SHALL BE 125 MICROINCHES OR BETTER." But someone has discovered this nonmandatory appendix that states "Surface texture should not be controlled on a drawing or specification unless such control is essential to the functional performance or appearance of the product. Unnecessary restrictions may increase production costs and mitigate the emphasis on specifications for important surfaces." The engineer interprets this as not to callout surface roughness at all.
lm





RE: Nonmandatory Appendices and Surface Roughness
Surfaces/faces need to be indicated which roughness is needed, or use a general note. 'How' this is accomplished is not indicated on the drawing.
Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion
RE: Nonmandatory Appendices and Surface Roughness
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Nonmandatory Appendices and Surface Roughness
We have a default surface roughness note on most drawings, however we set the value on each drawing depending on function/aeshetics. It's rarely left off completely due to aesthetic concerns but in theory I'd be fine with it.
If you use the symbol from B46.1 then this defines the 'or better' part as less rough and gets over the problem ewh spotted.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
Kenat-without the symbol is this note incomplete? I was trying not use the symbol just to keep all the notes together cleanly. Solidworks adds a hard return about the note to allow room for the symbol.
RE: Nonmandatory Appendices and Surface Roughness
If you really want to indicate that surface roughness shall be 125 microinches or better, I would suggest you word the note differently. Something along the lines of "Max roughness shall be 125 microinches" thereby allowing lower values to be acceptable.
RE: Nonmandatory Appendices and Surface Roughness
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
RE: Nonmandatory Appendices and Surface Roughness
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Nonmandatory Appendices and Surface Roughness
Maybe I didn't make it clear, while we have a 'standard note' for default surface tol, the actual value is decided on an individual basis, there is no default value.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
So, looks like my memory was playing up and I may need to look at changing our note. Oh well.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
The only other option to this is a specified range, and yes, RMS has been replaced by Ra.
RE: Nonmandatory Appendices and Surface Roughness
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
RE: Nonmandatory Appendices and Surface Roughness
That's what I'd take that specifific appendix to mean.
In your case does the surface finish matter?
Or if by general note you mean it will go on all drawings then I'd say it should be customisable based on individual drawing. The value should be set based on the requirements of each part, and if there are none on a specific part it should be deleted.
If you have a more general question about nonmandatory appendices, well, I think the description says it all. They are non mandatory, which means you can choose whether or not to invoke them. Who gets to make the decision of if you invoke it or not is up to your company.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Nonmandatory Appendices and Surface Roughness
"(a) Surface texture should not be controlled on a drawing or specification unless such control is essential
to the functional performance or appearance of the product.
Unnecessary restrictions may increase production
costs and mitigate the emphasis on specifications for
important surfaces."
This is clearly boiler plate that does not say surface finish should not be called out on drawings, it just warns against over usage for non-essential applications. Hence the word Non-Mandatory.
RE: Nonmandatory Appendices and Surface Roughness
Avoid jargon by using the ASME symbology; there's a default to RMS as I recall, and the value stated is the MAX RMS value then. The finish can be 'perfect' and be acceptable, or can be at the MAX RMS value and be acceptable. Note though that because it is an averaged limit and averaged measurement, you may have locally poorer finishes.
Jim Sykes, P.Eng, GDTP-S
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