Process Notes on a Drawing

[carloabarth]

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?

 

[MechEng2005]

What about just putting the revision level for "Part A":

NOTE: May be made from (Part A) Rev. (#)

Then, if "Part A" is changed and made unsuitable for producing "Part B", the drawing for "Part B" is still correct, assuming that the revision level for "Part A" was changed when the part was made unsuitable. If "Part A" is changed but still suitable for making "Part B", then perhaps you need to update the drawing for "Part B", but even if it isn't changed to say "May be made from (Part A) Rev. (# or #)", it still isn't INCORRECT. If the note for part B isn't updated, the machinist may be able to determine if the new revision of Part A is suitable anyways. In an ideal world, the machinist may even catch the fact and ask you to update the drawing, though I know some places communication between machinists and engineers is limited or non-existant...

-- MechEng2005

 

[KimBellingrath]

How about - "MAY BE MADE FROM PART 'B' PROVIDING ALL DIMENSIONS ON THIS DRAWING ARE MET"?
or - "SIMILAR TO PART 'B'"? this would allow them to find part 'B' and evaluate it's applicability as a 'make from' part.

 

[KENAT]

I'd hesitate about using rev letters as a distinuishing factor in official/permanent documentation.

To keep the same part number the change that causes the rev change must be backward/forward compatible.

Often the rev of parts is not marked on them even if the part number is, since they should be interchangeable.

Using rev letters to essentially define different parts is generally considered bad practice.

KENAT, probably the least qualified checker you'll ever meet...

 

[ewh]

I think the best method, which has been touched upon here, is to leave any reference of the M/F part off of the drawing and include it in other rider documentation. If any other part meets (or can meet) all of the criteria of the drawing, then it should be fair game as a M/F. To avoid configuration issues, it should NOT be noted on the drawing.

 

[drawoh]

MechEng2005,

Using revision numbers to identify parts generally is frowned upon.

Take that case that we share my part XXXX-RevB, and it meets all our requirements. I move holes and revise the part to RevC to suit some other parts I have modified. Surprise!

Note that the RevB drawing is obsolete, and no longer available for you to get fabricated.

Again, we share my part YYYY-RevB and again, it meets all of our requirements. This time, I discover that I have misspelled DISCOMBOOBERATE on page three, and I revise the drawing to RevC. How do you decide whether the part still works for you or not? This is especially awkward if I am the sort of person who does not fill in revision blocks.

This is nasty and complicated. Do not change form, fit and function.

JHG