Multiple configurations and separate drawing numbers

[321GO]

What's the best way to handle identical parts that only differ with regard to their surface treatment(for instance)?
The most obvious would be to make separate drawings for each of them, but that would be a lot of work and a nightmare when something needs to be changed.

Only use a default drawing number and specify upon delivey what surface treatment to apply? This method clearly also has a lot against it.

I'm kind of in the dark how to approach this practically, thanks a bunch!

 

[MintJulep]

Best is so subjective.

Some possibilities:

Dash numbers.

Part 1234-1 Finish zinc plate
Part 1234-2 Finish blue spray paint

Make from.

Part 1235. Make from part 1234, zinc plate it.
Part 1236. Make from part 1234, paint it blue.

 

[KENAT]

Like Mint says. If your configuration control practices allow 'dash' numbers then that can be a good way to do it. However, they just seemed to cause confusion around here when proposed so we didn't go anywhere with it.

A subtle variation on the above is to have one 'drawing' define 2 part numbers. Have a table on the drawing saying which PN applies to which treatment option. Again this can confuse things in systems where drawing number and part number are synonymous.

Alternatively doing a make from essentially means the geometry is controlled on one drawing while surface finish is controlled at the next level up. Some places will hate the extra BOM layer this introduces though.

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(probably not aimed specifically at you)
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[dgallup]

I like to use letter suffixes. No letter is the part without any coating, A is chrome, B is zinc, etc. That way you can always find the drawing as it's the base part number.

We also use this for things like o-rings. All o-rings made for a certain material get one drawing number which has a table of letter suffixes and dimensions.

The same approach works well for assembly drawing too. We make dozens of finished goods that look exactly the same on the outside but have different electrical resistance and or flow rates. They can all go on one tabulated drawing.

I absolutely hate putting multiple (and seemingly random) part numbers on one drawing. Without some kind of database system you have no way to find the right drawing short of just randomly opening them. Never the less, there are people in this company that seem to find this acceptable.

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[KENAT]

dgallup, I suspect your use of letters would be tricky in many US documentation systems as it could easily get confused with the use of letters for revisions.

Obviously revisions shouldn't affect interchangeability etc. but in practice, since ASME revision standards are based on use of letters I can see issues for many folk.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[MadMango]

As others have said, you should probably use a tabulated drawing calling out the various finishes. Alternatively, you could create a reference document that lists various finishes and create a general note pointing to this extra document.

PRO- this reference document can be used with other parts that have the same finish requirements, other finishes can be added as required.

CON- the document has to be controlled and made available to vendors, it should only specify like processes (one for powder coating, one plating, etc).

"Art without engineering is dreaming; Engineering without art is calculating."


Have you read faq731-376 to make the best use of these Forums?

 

[dgallup]

Kenat - We never put rev levels in part numbers and we use numeric rev levels (we don't do ASME), no chance of confusion. But a dash and a numeric works just as well. The main thing is every part on the drawing has the drawing number as the base part number with a suffix.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[ptruitt]

There are two main approaches that I am aware of. One is championed by Frank Watts and the other by David Garwood. I think it is important to give each of these serious consideration before 'investing'. I always suggest reading their books, in depth, before making a decision that can have extensive implications.

Peter Truitt
Minnesota