Part Number for Modifications

[jjengel]

Hi all,

I've been toiling with the task of researching, developing and implementing a part numbering system for the past few weeks and have come across an area which I need clarified.

In an older thread (

http://www.eng-tips.com/viewthread.cfm?qid=136028)

it is suggested that the a category for modifications be created. I was hoping to get a confirmation on how to define "modifications". This seems pertinent right now as we have an assembled printed circuit board that we order and then modify by replacing or removing a few parts. Essentially PCB part #XXX has two resistors removed and replaced with #YYY and. Now, I could see this being interpreted as either a modification or an assembly, or both (As I dig deeper into the CM topic I can see why this receives so much attention). Or does PCB #XXX become #ZZZ (a modification) after the removal of the resistors and then an assembly (#AAA) with the addition of the new ones?

Maybe it's all elementary, but I'm a one man dept with a lot of hats to wear, and need some help.

Also, thanks to those who have given so much useful information on the topic of part numbering in the past. The insight has been most helpful.

Jason

 

[KENAT]

Well, I'd generally say to avoid 'smart numbering' but it sounds like that horse has bolted.

Take a look at ASME Y14.24 for definitions of drawing types of drawings. Section 6 is especially relevant.

Your case sounds like a modification drawing.

Posting guidelines faq731-376

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

 

[jjengel]

KENAT,

The horse has indeed bolted, but I'm hoping that we'll be able to get it back. The company's been here for 10 years while I've only been around for two. The part numbering system is a mash-up of several other numbering systems that were brought in through acquisitions, coupled with an attempt at adding intelligence. Now the system's breaking down and no one can even agree on what it was supposed to be anyways. By and large I can't point the finger at any single person. Historically it's been a problem of too many people operating independently and no uniform system being laid out.

Utimately, I'm working to transition out of the semi-intelligent system. Ideally I'd like to see just a sequential non-intelligent part numbering scheme. The upside to the whole thing is that while the company is 10 years old, there has been no attention given to CM beyond enerting part numbers into our ERP system so I'm hoping that with diligence and effort we can stop digging this hole and eventually get out.

The reason for the original post was to address how to handle this if we were to categorize in the new system. It's all speculation right now. I'm really trying to look at this from all angles before committing to anything.

Thanks for the feedback.

 

[MadMango]

For PCB assemblies, I prefer it where the PCB itself would have a 5-digit number followed by a 3-digit configuration code that could be printed separately. I know many PCBs can yield different performance simply by changing driving components.

This would allow tracking of your PCB by the 5-digit, non-significant number, and after assembly, you could tell the various flavors of assembly apart due to the 3-digit number. This way you will know that P/N 12345-000 is a bare PCB while 12345-001 has YY components and 12345-002 has XX components.

It places a little intelligence back into the numbering scheme, but I think in the long run it makes more sense.

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

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

 

[KENAT]

If you were just adding components then I'd agree with making it a next level assy drawing.

However, given you're removing parts I think it's closer to a modification.

The modification drawing can still have a 'BOM' of sorts if need be.

Posting guidelines faq731-376

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

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

 

[jjengel]

MadMango,

I definitely see the benefits to assigning numbers like that, if the PCB had several configurations in use. The PCB in question is modified for only one application and there are no plans to use it anywhere else for any other purpose.

KENAT,

Modification was my thought too. It's a matter of swapping out some resistors, swapping a S-RAM, and adding a clock. Kind of a gray area of 2/3 mod and 1/3 assembly. Majority rule?

Thanks again for the input.

Jason

 

[jjengel]

As an afterthought, here's an example of what I'm up against in terms of part numbers and the attempt at intelligence:

EC-1000-001 (The EC is a project designator, the 1000 indicates manufactured part, and 001 is part number. 002 would be the next manufactured part purchased for this project)

EL-1011-001 (EL designates electrical part, 1011 is meaningless, 001 is part number, 002, 003)

25-001 (25 designates hardware and 001 is the first piece of hardware ever purchased with 002, 003 to follow)

EC-25-001 (EC is project designation, 25 is hardware designation, 001 is first part purchased, 002, 003)

BD-2001-001 (BD is manufacturer designation, 2001 indicates paurchased, 001 means first...)

PH-4000-001 (PH is project, 4000 is supposed to indicate some sort of sub-assy, 001...yup first sub-assy assigned a number)

ECO-106125 (I'm especially displeased that this was ever used because we issue 6 digit engineering change orders. In this case ECO is project designator and the 106125 is the vendors part number)

Needless to say, it's tough putting together an IPB and making sure no one confuses 25-016 with an EC-25-016 (both hardware pieces) either in the field or here in the office.

Has anyone else ever encountered and repaired a system that was as clunkily laid out as this?

As always, thanks for any input.

Jason

 

[MadMango]

Can you put a cross-reference table on the drawings (or database) for the old vs new part numbers?

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

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

 

[jjengel]

MadMango,

That's exactly what I want to do. Accounting is putting up a fight over how much this more time-consuming this will be if implemented. My thought is that we're not using our ERP system nearly as efficiently as it was intended to be. I know that we can set up tables to cross the part numbers, and plan on moving forward with it. In the meantime I am in the information gathering phase so that I can adequately address the objections.

I'm really leaning heavily towards a 100% non-significant numbering system. Our ERP can handle the segregation of parts into manufactured or purchased, hardware or electrical, etc. and I see no reason to add a layer of redundancy. Coupled with a strict adherence to rules for interchangability and revison, I think we'll be solid...eventually.

 

[MadMango]

Well, I think you are on the right path, and hope someone higher up the ladder can help you in your fight. Many groups in an organization feel their ERP systems are only for their use. Somehow they fail to see the big picture, in that the system is there to make everyone's life easier.

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

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

 

[PeterStock]

I would suggest not putting a cross reference table on the drawings, but keep a separate database for the purpose. The drawings should show the number in use at the time of issue, unless revised. If possible I would keep all the different part numbers in your ERP database with cross references for case where a part has more that one number. I would try to keep only one of the numbers active, all new drawings would use the new number and any assemblies that are revised would need to have all numbers updated.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net