【转帖】process notes on a drawing

yang686526

process notes on a drawing
here's a question:
is it "acceptable" to put a note on a part-drawing stating that the part (part a) can be made from another part (part b) controlled by another different part-drawing.
i think we are trying to keep process notes like this out of drawings, and let manufacturing decide if they want to use another part to make a part, but in this case manufacturing wants the drawing to specify that it is ok to do so.
i'm worried that we open ourselves up to a document control nightmare where we have to change the drawing for part a if we change part b in some way....
opinions?
i've certainly seen it done before, especially if you are modifying a purchased item.
it is common for casting, where you have a drawing for the raw casting, and a finished part drawing to define the machining and such.
seems to fall in a grey area.  is it really process information, or is it material information?
i've seen it done before too.
common on machinings/castings either where different items are made from the same blank or even where the forged/cast part has its own drawing to aid documenation etc.
i've seen it done in at least one case where there was a part that could be made either by modifying an existing machined part or by making it from scratch.  this was in the uk though.
we also used to do it a lot for specials & the like.
depending on how you word it i don't see that you are specifying manufacturing methods which is discouraged (asme y14.5 1.4(e)).  if you say "may be made from part xxxx" i don't see a problem.  in fact it's kind of like when you give options on the base material, either different grades or even "may be machined from stock or forged blank" which i once used.
kenat, probably the least qualified checker you'll ever meet...
a "made from" is acceptable. but having process notes may cause trouble. better to leave them and have them on a job traveler of some sort.
chris
solidworks 07 4.0/pdmworks 07
autocad 06
as regards your configuration control concern.
well, the change to part b shouldn't affect function, form or fit and should be fully backward & forward compatible, or it would have to be a new number anyway.  
so while it may be a possibility i'd guess it to be unlikely.  
it's no more of a nightmare than having to update assembly drawings when a part is changed.
kenat, probably the least qualified checker you'll ever meet...
thanks for the feedback guys.
the note that is desired is "may be made from part b" which is a little different from saying, "may be made from a blank".  the concern i have is keeping up with all these such kind of cross-references which are not formalized in our configuration management system.
-damon
like i said, i've seen it done the way you just clarified.  it may not be ideal but i'd say can sometimes be justified.
as regards the config control issue, like i said most issues should be covered by the fact that to keep the same part number and only be a rev the change must be backward & forward compatible.
things like finishing can cause problems as usually change in finish (e.g. cad plate to zinc) is considered back & forward compatible but sometimes for compliance reasons isn't really.
however, if in doubt do you have some kind of production permit or waiver system?  you could perhaps have one which says "part xxxx rev a may be made from part yyyy rev c" using revs to differentiate is normally bad practic but for a waiver may be ok and avoids the configuration issue to some extent.
kenat, probably the least qualified checker you'll ever meet...
i prefer "made from p/n xxxx" or "m/f xxxx (xxxx=part number)". you can also add "m/d xxxx, opt".
chris
solidworks 07 4.0/pdmworks 07
autocad 06
however ctopher, saying "made from p/n xxxx" says that's the only thing it can be made from.  my interpretation of the op is that it can be made from scratch or from an existing part.
what's "m/d xxxx, opt"?  opt is optical or optimium to 14.38, optl is optional, am i being dumb?
(minor pedantic point "/" has pretty much been dropped from standard abbreviations in asme 14.38a-2002 and 'made from' isn't in there anyway.)
you can always add the base part as a raw material in the bom of the "made from" part in your erp/pdm system.
"art without engineering is dreaming; engineering without art is calculating."
madmango, i was thinking the same thing but some systems make this difficult.  i'm led to believe that with our implementation of sap it's difficult to add a bom to something that's categorized as a piece part.
or something, i'm no erp expert.
kenat, probably the least qualified checker you'll ever meet...