Should parts have revision

[ChrisPLM]

Hi;

I would like to pick of the PLM guru's brain.

For nearly 2 decades, I have implemented PLM processes and systems and everytime not only the system offer the capability to revise parts but it was quite logical that parts have revisions.

Recently I came across this

https://www.buyplm.com/plm-good-practice/plm-software-part-revision-form-fit-function.aspx

They claim that parts must not have revisions

What do you all think about that?

Thanks

[BenLoosli]

Interesting concept.

The main reason for having revisions is for traceability. I worked for an air bag manufacturer and we got sued by someone who was burned by an airbag. We had to go back in the files and produce drawings that pertained to the serial number of that particular air bag inflator. Without revisions, how would you track the changes made along the way to keep the design current.

Maybe the use of revisions deals more with the paper drawing than the actual part, but both can have changes during their life that require tracking.

In some companies, you also need revisions for the release process, to tell manufacturing, be it making the parts or using them in an assembly, that there has been some change and that this new revision should be used. That also implies a disposition process to handle the when to start using the new parts and how to handle the older ones.

[ChrisPLM]

Thanks Ben

what this website says is that you manage the revision at the document level, not the parts.

Otherwise, in my world, I have always done as you are describing). Therefore I was surprised by this new concept and wonder if this is simply just antiquated...

[ScottMorris]

Interesting article. I have not seen the PLM revision included with the part number as part of inventory or production, only in the PLM application. They are correct to state that functional equivalents do not need a revision identifier in the part number. If the previous part is no longer suitable, it should be superseded with a new part number. I agree with their statements in the "Part Database records have revisions" section.

I'm sure there are companies out there with a rev identifier in their part numbers, I've just never encountered it.

[ChrisPLM]

HI Scott,

always as quick to respond 🙂  Thank you

I am obviously not advocating that part should not have revisions. I am just trying to understand this parallel universe I just discovered (after nearly 20 years in the field) and wonder if my network has come across such a concept.

That person told me that the documents (be they CAD or non CAD documents) have the revisions, therefore the parts don't need it. I did not manage to convince him otherwise until now.

Regarding revision in the part number. I have come across this within a company that had very old manual-intensive processes.   Once they moved into more modern processes and systems they quickly forgot about having the rev in the part number.

I have visited a bit more their PDXpert website and it seems that is quite outdated concepts and systems. In one of the videos, they refer to the drawing as if it was the master of everything....   Nowadays we want to remove the 2D drawings altogether.... This says it all.

Let's see who else responds and see if they share the view that part should not have revisions (I doubt it, this is a PTC forum after all so most people here would use Windchill and as far back as PDMLink 6, parts had revisions. so people here would adhere to PTC ways of working 🙂 )

[avillanueva]

I will like again to Oleg's blog on this topic and related posts: https://beyondplm.com/2021/03/31/fff-form-fit-function-revisions-and-interchangeability/

In a purist sense, the article on buyplm is right speaking strictly of inventory. My refrain has been "close your eyes and pick a part from the bin of mixed revisions at random. If they will all work 100%, congrats. If not, you should have changed part number." In ERP, this is very true that revision should not matter assuming you are applying FFF rules correctly. If folks at your site claim it matters, perhaps they are not controlling things properly and treating revisions like FFF. For example, if they say that the B rev is what they need to build and you are on rev E, you've got fundamental problems.

That being said, were revisions help is when poop hits the fan. If you have to trace down a field failure and you need to know the extent of the problem, denoting revision and when changes were incorporated is very important. Since Windchill BOMs are integrated with the Part object, you are going to have them and you need some snapshot point to compare release to release. Date can be used as an analog for revision. 

Note also that BOMs are single level. You are only controlling the parts at that level, qty, UOM, etc. You are not specifying the revisions of those components. Windchill links the the part master of components and you need a config spec to resolve to a revision. Here is where we get into the concept of effectivity and a whole new world.  I always look to automotive. Do you think the multi-level BOM of a Honda produced in January is the same as one produced in December of the same car year? 

We operate simply, syncing model, drawing (or document) and Part (BOM) revision. Need to change one, you change them all.  It simplifies the workflow for the end user since they are so inter-related. Let's say that a PLM system treated a BOM distinct from the Part. You could say that the part is without revision but it just shifts the revision to the BOM.

If you operate with mixed revisions, where drawing, BOM and CAD model can float independently, that's a workable solution but you need to track things a bit differently.  Each one can introduce changes that impact the final product.  You system needs to keep track of that collection, what was the revision of each at any point in time. 5 months back, the drawing was at C, the model at D and the BOM was at B.  

I could go on but simply put, in ERP, 100% revisions should not matter but can be helpful as a cadence of change.  On PLM side, if BOM is integrated to Part object, it must have revision or some means of snapping release points.

[ChrisPLM]

Thanks for your detailed answer and for taking the time to write. 

The bottom line as I understand it, if you consider the topic company-wide: Part must have revisions