Internal Part Numbers

[BridgetK]

In the military contracting environment, what is the general concensus on the use of internal part numbers? I have (for many, many years) used internal part numbers to control even off-the-shelf components such are resistors, capacitors, etc. The approved manufacturers list would then provide detail on the manufacturers and their part numbers that can be used for a specific internal part number. I am being told that military contracts are now being written to require that the manufacturer's part number (COTS number) be used instead of internal part numbers. This means that bills of material would use only the manufacturer number and each alternate would be placed as a substitute.

My concerns are:

1. The manufacturer is being given approval to make any changes to their component without notification. With internal part numbers you create a source control document that the approved manufacturers meet.
2. Different manufacturers may use the same part number to represent different parts which would cause a duplication of part numbers in our system.
3. Increased workload for maintaining parts, boms, etc.

Any comments on this would be greatly appreciated.

 

[zeusfaber]

Internal part numbers have lots of advantages - as you suggest, they form part of a regime that can give you good configuration control, and good supportability.

The downside of the system is that it costs a lot of money to set up (all those source control documents that have to be written in the first place, then updated whenever the component goes obsolete again).

In a world where the taxpayer won't let you start military projects until you've promised that the acquisition costs are going to be less than 80% of what they need to be to do the job properly, little details like configuration control and supportability often go to the back of the queue. It's a choice between accepting an imperfect job or not getting new kit at all.

There's always a living at the other end for some ingenious soul who's willing to sort it all out/keep it all together.

A.

 

[BridgetK]

Thanks for the response.

We have a couple of advantages here. Our source control document for the electrical components is basically the form in our PLM system. We list the basic attributes and the approved manufacturers and their part numbers. In addition, all of the components used in our production programs (and many of the ones in R&D) already have internal part numbers assigned. So that work is all done.

My 'battle' is that we have a couple of people that are from an R&D-only or one-time-build environments and they are pushing to get everything changed to eliminate the internal part numbers. Of course our in-house designs would still have internal numbers and drawings, specs, etc. to define the design.

As CM Manager, I see the advantages of the internal numbers and feel that I would need to add resources to support the change. They would still want the alternate parts linked in our system so instead of having one internal number with five approved manufacturers (as an example), we would have five part numbers in the system with each of the other four sources listed as alternates. In effect, there would really be no AML. Just five times the work.

I am trying to be open minded and that is why I am seeking outside opinions.

 

[VEBill]

If the Source Control Drawings / Documents (SCDs, as they're often called) offered an over-all advantage, then they be in common use outside of the military environment. But they don't, and they're not.

As already mentioned, it's a hugely expensive process. It also makes the parts list next-to-useless unless it includes another column listing the generic P/N (which opens up many of the risks that SCDs seek to avoid). To decipher a PL full of SCDs, one wears out the carpet between your desk and the data bank. It can take days. So the added expense of SCDs continues into the far future.

One way to achieve the same outcome is to insist that all vendors are ISO-9000 and CMMI (and all that stuff) certified. This will (hopefully) ensure that their QA processes and CM/DM are sufficiently under control that all the parts delivered under a certain PN will be consistent.

Hopefully these sort of certifications "...don't cost, they pay."

One of the key concepts is that risk = profit. Although this needs to be applied ethically, if an organization is unwilling to accept any risk (i.e. mgt insist on SCDs to reduce risk) then the profit will be very low or worse.