Polishing notes on a drawing

[JHTH]

Hello, everyone,

I am looking for a reference to the definitions of P1, P2 and P3, which describe the levels of polish applied to one or more faces. From memory, P1 means remove gross defects such as scratches and P3 is a mirror finish, with P2 somewhere in the middle but can anyone be more specific?

Thanks in advance,

Jon

JHTH
NX 7.0.1.7 + TC 2007

 

[prdave00]

This is the first time I've ever heard of grades for surface finish, with the exception of stainless steels (i.e. 2B, #8, etc.).

I can't recall any "grades" being specified or discussed in ASME B46 or Y14.36, so maybe it's a ISO thing as shown at

http://www.roymech.co.uk/Useful_Tables/Surface_Texture/Sur_Fin_Values.html

that has "N" grades.

Why not just call out the surface finish requirement in terms of Ra, Rz, etc? I figure any "grade" will eventually point back to a quantifiable level of finish.

 

[btrueblood]

I've seen the P1/P2/P3 notation in optical drawings (e.g. lenses) before, but dunno the standard that discusses them. Would agree with Prdave00 that it likely is an ISO thing. It may also be a mold-making thing, i.e. talk to a mold shop about how they specify surface finishes.

Of interest may be the standards for surface finish, see the Wikipedia article, which has references to the relevant ASME and ISO standards. Note that one of the callouts for "lay" (which would go inside the square root symbol for surface finish) is a "P" - for particulate:

http://en.wikipedia.org/wiki/Surface_finish

 

[JHTH]

Thanks for the replies. The particular example that caused me to ask the question was on a lens drawing but it also formed part of the drawing standard at my old company (which was based on the ISO standard).

I'll try to contact someone there but in the meantime if anyone can advise on this I'd be very grateful.

Thanks,

Jon

JHTH
NX 7.0.1.7 + TC 2007

 

[pmarc]

Are you going to paint or coat metal surfaces? I was able to find a document which specifies three grades of metal surface preparation P1, P2, P3 before painting or coating (see link below, page #5).

http://resource.npl.co.uk/docs/scie...cations/online_guides/pdf/surface_coating.pdf

However I am not sure if this is what you are looking for.

 

[JHTH]

Hi, thanks for posting but that's not what I'm looking for. That said, it looks like a pretty useful document so I'll save it anyway.



Cheers,

Jon

JHTH
NX 7.0.1.7 + TC 2007

 

[dgallup]

The society of the plastics industry (SPI) moldmakers division has a scale for the polishing of mold cavities. It goes from A-1 to D-3. There is an older society of plastics engineers (SPE) scale that goes from #1 to #6. It's obsolete but you still see lots of references to it.



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