Should have different part codes if they are interchangeable? 2

[Gianfranco]

Hi all,

1. In your opinion, and experience, two or more interchangeable parts should have the same code or, viceversa, different codes?

2. Which is the definition of interchangeabiliy of parts?

3. Which are the aspects that are to taking into account to settle the interchangeablity of parts?

Thanks for your advices.

Gianfranco


PS. Message for Norgranite about Form Fit Function. May be you know this at

http://help.sap.com/industry/discrete/en/08/a111064d7611d2b438006094b9c9be/content.htm.

 

[pavanje]

Some of the ways we end up with interchangeable parts are
1. Improvement over an old part. Use only the new part from now on.

2. The parts are from different vendors. They all work fine but they are not identical. The cost and reliability of vendor may be the factors in deciding the part.

3. Different customers require different features. Some are not so particular. You may have no. of parts for no. of customers. Those who are not fussy, any one of them can be used.

In any case you need to identify the parts. Hence different codes.
If you are using ERP packages (SAP/BAAN..) you can identify these parts as interchangeable. In BOM you can select any one.

 

[MadMango]

In my experiences, I have only seen multiple parts that work and fulfill all aspects of FFF as being purchased OEM (off the shelf) parts. Things such as motors, washers, linear actuactors, etc. In these cases, the parts were controlled by a single Vendor Item Control Drawing or a Source Control Drawing that listed the various OEM parts that were similar.

I think if you have 2 parts that differ in any way (material, finish, etc) then they need to have different part numbers.

Interchangablility
I can't find a true definition for this, but if a part is identical in Function (rated load, torque), Fit (mounting locations, size) or Form (material, color) then I would consider it "interchangable". Of course there are always exceptions to every rule.

For example, a SST washer and a Zinc plated washer... not very similar. But if the SST washer is only being used as a shim or spacer (or no harsh evironment), the Zinc washer may be a good replacement and may be considered interchangable.

Basically, if the replacement parts are equal or superior in performance to the existing part, I would consider it "interchangable". "Happy the Hare at morning for she is ignorant to the Hunter's waking thoughts."

 

[GregLocock]

In the automotive world we often introduce parts superceding old ones. They ALWAYS get a new part number at the design and releasing level, but Parts and Accessories make their own call as to whether they need a new part number, based on whether the old part can substitute for the new part, and vice versa.

If parts are produced to exactly the same drawing by different suppliers then I believe they would get the same part number, but this is not a normal occurrence. If one supplier takes over from another they would almost invariably redesign the part, triggering an update in the part number. Any change to the design intent of the part triggers a part number increment, although corrections to the drawing and 'invisible' changes can be handled by incrementing the drawing revision number, at least on paper drawings. I do not know how we do this on computer models. Cheers

Greg Locock

 

[Gianfranco]

Pavanje (Pav), MadMango (MM), Greg (GL),

Many thanks for your interesting replays.
Let me summarize your opinions and mine (GI) and let permit me expose a criteria to be used for setting the interchangeability of parts.

1. Two, or more "similar" parts, should have the same code or, viceversa, different codes?

Pav MM GL GI
1.1 If the part have higher FFF dif dif dif dif
1.2 If the part have the same FFF dif* dif dif equ^

* ERP packages permit the identification of a part as interchangeable with others

^ Only if all functions are the same. The case done by MM is appropriate: two washers one in SST, the other Zn plated. In this case the absolute FFF/performances are higher for SST. But we need an evaluation of the relative FFF to the application, in order to set the interchangeability of the parts.


2. Which is the definition of interchangeabiliy of parts?

2.1 One part is interchangeable to others (old one o new one) if, and only if, the application (that specific case) requests the same FFF/performances.

2.2 Two parts are non interchangeable to others (old one o new one) if the the application (that specific case) requests higher FFF/performances.


3. Which are the aspects that are to take into account to settle the interchangeablity of parts?

3.1 The FFF requests, by that specific application, shall be take into account to set the interchangeability.


Are you agree with this more appropriate criteria at point (2) to decide if the part is or not interchangeable?

The coding of that part will depends on the packages and ... experience of the guy - for that specific application -in charged of the coding activity.

And we know that that guy - in charged for coding the part - is, generally, not experienced enough to evalutate the FFF/performance of the application.

And, therefore, pratically, you are right: it is better systematically, always change the code of the "similar" part - and, potentially "interchangeable parts". Do you agree with me?

Thanks, friends, for the useful discussion. It has changed my original point of view.

Gianfranco.