Config Mgmt & Assy Revisions/Numbers

[mousemat]

Hi All,

Ok so I've read quite a few posts on this forum on these sorts of issues and I'm a bit confused, in particular with respect to assemblies, but I think I understand that a recommended way for control of parts is handled by either:

1) The drawing number for a part is revised (ie Rev 1 to Rev 2) only when the part is backward/forwards compatible, fit form function etc
OR
2) Otherwise the part gets a new part number.

Now my main questions are what happens to the revision and or number of the sub assembly that the part belongs to for each of the above scenarios and what about higher level assemblies?

Thanks

 

[swertel]

Each higher level assembly would get a new part number up until interchangeability is restored.
I also recommend that you change the part number for every higher level assembly up to the point where traceability is restored.

Example 1:
part 12345-1 is olive drab.
part 12345-3 is black.

assembly 54321-1 contained part 12345-1. I probably need to create a -3 of the assembly for the black configuration because although the part is interchangeable (form, fit, and function) I may want to have traceability when the customer wonders why a green part is now black.

Example 2:
Part 7890-1 is an ID label.
Part 7890-1 is used on assembly 9876-1.
MIL-STD-129 got modified and now I need to include a 2D barcode on the ID label.
Because the ID label is obviously different, I create 7890-3 and replace 7890-1 in assembly 9876-1. I don't add a new dash number to the assembly because interchangeability is restored at that assembly level and I maintain traceability via serial numbers and/or lot numbers to know which assemblies have the old ID label and which have the 2D barcode.

--Scott
www.wertel.pro

 

[KENAT]

Yep, like swertel says you chase it up through the assy structure until your reach a level where they are interchangeable.

Posting guidelines faq731-376

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

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

 

[KENAT]

By the way, technically some of this applies to 'part number' which is not always exactly the same as 'drawing number'.

Posting guidelines faq731-376

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

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

 

[mousemat]

Thanks for your replies swertel and KENAT.

Swertel - in regards to your second example 1) does that mean that assy 9876-1 is also up revved - I assume it would have to be and 2) would you track assy 9876-1 (noting its revision level) against serial and/or lot numbers or would you track part 7890-1 and 7890-3 against the sn and/or lot numbers? I know the second question is probably semantics.

Thanks

 

[swertel]

1) Yes, mousemat, the assembly has to be revised in order to exchange the -1 with the -3.
2) The S/N and or Lot Number is tracked at the assembly level because it is at the assembly level where you require traceability to determine when the new label was added.

--Scott
www.wertel.pro

 

[mousemat]

Ok thanks swertel. And I assume you'd track all the revision levels (of parts, sub assy & assy) via a list of drawing numbers which contains their revision level?

Cheers

 

[swertel]

Yes. A product baseline that shows the revision levels of the documents is used for tracking.

Remember that documents gets revision levels, physical items do not.

--Scott
www.wertel.pro

 

[mousemat]

Remember that documents gets revision levels, physical items do not.

OK

By the way, technically some of this applies to 'part number' which is not always exactly the same as 'drawing number'.

I know that the pn and drawing number can differ, not sure why though, but can you elaborate on what you meant with respect to this discussion please?

 

[KENAT]

ASME Y14.100-2004 (version I have to hand) makes the distinction at para 6.6.

"A Part Identifying Number is the same as, or is based on, the controlling drawing number"

One example is that a single drawing may sometimes describe multiple part numbers - such as with 'dash numbers'.

Posting guidelines faq731-376

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

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

 

[mousemat]

swertel and KENAT - thanks very much for your assistance! Cheers

 

[swertel]

Cheers.

--Scott
www.wertel.pro

 

[KevinZ7]

Each higher level assembly would get a new part number up until interchangeability is restored.
I also recommend that you change the part number for every higher level assembly up to the point where traceability is restored.

Example 1:
part 12345-1 is olive drab.
part 12345-3 is black.

assembly 54321-1 contained part 12345-1. I probably need to create a -3 of the assembly for the black configuration because although the part is interchangeable (form, fit, and function) I may want to have traceability when the customer wonders why a green part is now black.

Example 2:
Part 7890-1 is an ID label.
Part 7890-1 is used on assembly 9876-1.
MIL-STD-129 got modified and now I need to include a 2D barcode on the ID label.
Because the ID label is obviously different, I create 7890-3 and replace 7890-1 in assembly 9876-1. I don't add a new dash number to the assembly because interchangeability is restored at that assembly level and I maintain traceability via serial numbers and/or lot numbers to know which assemblies have the old ID label and which have the 2D barcode.

Wait, I am confused. How is interchangeability restored at the assembly level of 9876-1?

If you follow the steps outlined above, and up-rev 9876-1 from, say, RevA (includes 7890-1, no 2D barcode) to RevB (includes 7890-3, now with 2D barcode), now you may have inventory of 9876-1 RevB that meet the new MIL-STD-129, and some inventory of 9876-1 RevA that do not meet this new standard.

Shouldn't the assembly 9876-1 get a new dash number since it has new requirements to meet?

 

[swertel]

If that requirement is one of your decision factors for determining interchangeability, then you are exactly right, you may need to create a new dash number. But, in my example, that is not a requirement based on any number of assumptions.

1) I don't have any inventory.
2) I have inventory, but the disposition on the revision was to rework or scrap the existing inventory.
3) I have 9876-1 (Rev A) in the field at customer locations, but I maintain traceability through serialization or lot numbers.

--Scott
www.wertel.pro