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Aligning PDM and PLM with Part and Design Business Objects

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I’ve been reading up lately on the differences between Product Data Management (PDM) of CAD data and Product Lifecycle Management (PLM) of part data. I must confess that I used to think of the difference between them as one of degree and not of kind — that PLM was basically PDM on steroids. But more and more I’m coming to the conclusion that I was simplistic in my understanding. The truth is that they are different tasks altogether. Because of this misunderstanding I came up with some very inelegant solutions to some of the data management issues I encountered. I have been looking for better solutions. As it happens, it seems that Teamcenter now provides us with a means for making this distinction between PDM and PLM by maintaining two independent structures, a CAD BOM of Design items and a Part BOM of Part items, and then aligning the two. Although I have some concerns with the process, I think it has potential and should be explored.

When CAD models don’t equal Parts

I think that a lot of us who come from a Mechanical CAD background tend to think of the CAD model as being the part. Naturally, if there’s a part 1001 we think that the thing to do is to create an item in TC numbered 1001 and place the CAD dataset for it underneath. And lo and behold, that’s just what my NX Manager integration will do for me automatically when I create a CAD model called 1001; the item is created in the database and the dataset is placed underneath. It all works beautifully.

Except for when it doesn’t work.

Sometimes an entire assembly of MCAD models will represent a single part. For example, a part purchased from a vendor is typically listed as a single part on the BOM, but may be modeled as an assembly of CAD models. The models of the components don’t correspond to any Part number in the system.

Sometimes It may be desirable to use a single CAD model to represent many different parts. For instance standard parts that are geometrically identical but which have different finish codes. Parts defined by a Selected Item Drawing would be another example.

Other times you may want to represent a part with many different CAD models, for example if the model is of flexible wiring which may be routed in one path in one assembly and another in another assembly (or even in multiple different ways within the same assembly).

And then there’s Electrical CAD, ECAD. Frankly, I had to have it explained to me a couple of times that a single ECAD model actually defines many parts and that there is no CAD model of them individually. Not that it’s really a hard concept to grasp, it’s just that it’s a much different reality from the preconceived notions I had. Sometimes you need to walk right into your own blind spot to know it’s there.

So clearly the idea that you can simply create items for your parts and put their CAD dataset underneath them is at times too simplistic.

Parts, Designs, and CAD-BOM Alignment

Teamcenter now provides a pair of Business Objects that address this dichotomy between managing CAD and managing Parts: the Design and Part Item Types(*). The intention is that Design items will store your CAD data and that Part items will contain such things as requirements documents and analysis data. Designers will create design items which have product structures that represent how the CAD data is assembled, while Part Planners will create Part structures that represent how the parts are maintained by the business systems, e.g. ERP. These two structures are then aligned so that the CAD Design data is associated with the Parts which it represents.

(*)I guess that “Item Type” isn’t really proper terminology any more but I use it for Business Objects which are subclasses of Item.

Representations

One thing you’ll notice right away about Part and Design items that differentiates them from other types is that Parts contain a Represented By pseudo-folder and Designs contain a Representation For pseudo-folder. A Part’s Represented By folder contains all of the designs which represent it while a Design’s Representation For folder contains the parts for which it is a representation.

A design can be associated with a part by copying the Design revision and pasting it into the Represented By folder of the corresponding Part. The Design’s Representation For folder will then automatically be populated by the Part revision. The default cardinality of the Represented By/Representation For relationship is many-to-many, so one Design may be a Representation For many Parts and one Part can be Represented By many Designs. This addresses the various problem scenarios discussed above, if you want to have one Design represent many geometrically identical Parts, paste it into the Represented By folder of all of the Parts. If you have one Part which has several different configurations you can paste multiple Designs into its Represented By folder.

CAD-BOM Alignment

Finally, there is a process for aligning a CAD structure to a Part BOM. I’ve only just started working with this myself so I haven’t finalized my opinions yet, but I’ll share what I know so far. The process is to send both structures, CAD and Part, to Collaboration Context which will lay out the two structures side by side. You then select the Design and Part you want to associate and select Tools→Structure Alignment→Publish Data. When you do this you’re given the choice to Globally Associate the Part and Design, which has the effect of creating the associations in the Represented By & Representation For folders. Once the structures are aligned you can send the Part structure to the viewer and visualize the structure the same as if you were looking at the design structure.

 

Conclusions

Some final thoughts:

A Design for Every CAD model?

If a CAD design and a Part truly do have a one-to-one relationship, as will usually be the case for MCAD parts and designs, do we really need two separate items which then need to be aligned? On one hand it seems to be adding clutter to the database to create both a Part item and a Design item when only one is really needed. On the other hand, if all CAD models are stored as a single Design type then it makes the users’ lives much less complicated since they don’t have to make the decision of which Item type to use. If there is a choice to be made between picking a Design item type and a Part item type you know that sooner or later someone will make the wrong choice.

Alignment

I admit that I need to play with the alignment process more before I make a final judgement, but the process of aligning the two BOMs appears tedious and prone to error. I’m not sure how willing users will be to take it on. Finding the right pair of Design and Part items to associate looks like something that won’t be much fun if the structures are large or not laid out with similar structures. It doesn’t seem like Collaboration Context takes advantage of any preexisting Represented By/Representation For relationship between the Parts and Designs, but perhaps I’m wrong about that.

Opportunities for automation

It seems to me that there’s a lot of opportunity for automation. For example, by defining naming conventions for Parts and Designs one could implement some custom post-actions on Part and Design creation that would automatically associate the two. If you said that the naming convention for Designs was partnumber-DESn, then a post-action on Design create could search the database for a Part identified by that part number and automatically associate the two. Likewise, a post action on Part creation could search the database for all designs using that core part number and associate those to the part. That wouldn’t automate the case of one design representing many Parts, but it would simplify lots of the use cases.


Further Reading

PDM or PLM: Top Down or Bottom Up?  and PDM vs. PLM: Implementation Gaps discuss the conflicts between managing PDM and PLM in conceptual terms.


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  • http://passionforplm.blogspot.com/ Atul

    Nice blog…
    I had same questions in ma mind….
    Got clarification from ya.

    Thanks,
    AK

  • Narasimha

    Scott,

    There is one teamcenter product called as Teamcenter Product Master Management(TCPMM).CAD-BOM alignment feature(CBA) is one component among it.I have installed it but I have no application front idea,after reading your blog i think TCPMM is basically used for this purpose.Please correct me if I am wrong.

    Regards,
    Narasimha

  • Scott

    @Atul — thank you!

    @Narasimh — I’ve not heard of that product. Was it an application within another product? TC “Unified” merged several products into one; perhaps that came from one that I’m not familiar with. My background is with TC Engineering/iMan. I’m wondering if TCPMM came from Enterprise. Or, maybe I just missed it.

  • Narasimha

    Scott,

    TCPMM is another teamcenter product like enterprise,community etc…It has seperate software kit similar to teamcenter unified.It has seperate documentation too…

    TCPMM consists of 3 components:

    1) Usage Server
    2) Companion Server
    3) CBA Server (CAD-BOM alignment server)

    #1 is installed using TCPMM kit #2 and #3(with cad-bom alignment feature selected) are installed from TcUnified Kits. TCPMM was earlier called as TCBOM. Usage Server has seperate client similar to our teamcenter client.

  • Scott

    Narasimha,

    well, you got me curious because I can’t find much of anything on that product. Google gives me about three hits. One hit I did find was this guy’s linkedin profile, which mentions, “TcPMM integrations with other ERP / MRP systems(~ SAP).” From that little bit it sounds to me like TcPMM is for integrating with BOMs in other, external, systems, such as SAP. Does that sound right to you? The CAD-BOM alignment I was referring to in this post is for BOMs which are both stored in TC.

  • Paul

    Good post Scott.

    My understanding is TcBOM/TcPMM runs all possible permutations of a BOM in sync with ERP as a precalcuation. So for example all permutations of all possible options/variants for a Car model would be predefined and stored so they are readily available for like website wizard consumption, but it also would sync to ERP to perform this CAD-Part alignment in Batch where the Design is stored in TcUA and the Part in some home grown/external system. Like you said Scott, what you are discussing here is all internal to TcUA.

    Totally agree with your comments about the need for more automation in the alignment area. Interesting In TeamcenterForSimulation they have a structure map capability that can create a second structure based off XSLT mapping rules from an originating structure; this allows you to generate an entire analysis BOM structure from the Design Structure based off your business rules…you can even manage many different maps. I don’t think this will work in this use case because the CAD/EBOM structures in this case mature in a much more coupled fasion. But some type of slick automation like that is required. There are decent accountability tools to ensure you have aligned all you thought you aligned.

    There is also a command line utility that allows you to convert your sub Item types to either Design or Part. This is handy if you want to move to this model. It will convert a specific list of IDs or the database as a whole. It is a one way conversion from Item to Design or Part and from Design to Part. You can’t go backwards so be careful. Today we are moving all CAD to the Design Items, knowing we could convert to Part later if we decided to go with a single BOM.

    It seems for large Programs Design/Part segregation may be required and desired, but for smaller programs it seems like more overhead than is required or desired.

    Will be curious to see how this technology area matures.

    • Scott

      Great input, Paul. Thanks for participating.

      So this utility you mention in pp 3 cannot convert Part items to Designs then, correct? It’s interesting that there’s any tool available for converting item types at all, my understanding was that SPLM doesn’t support changing item type in TCUA — except perhaps when done by one of their services people.

      what would be your thoughts of separate BOMs for a large number of very small programs? Or for the case where CAD designs are created for a fast-n-dirty proposal using “dummy” part numbers that are never tracked by ERP because the contract, if won, will specify the actual part numbers to use?

      Thanks again,

      Scott

  • Alfredo

    Hi Scott… I founded your blog in Linkedin and I have to say it was a great discovery.

    Regarding this post, I would like to add more complexity. Let’s think in how will be managed the attributes of PLM integrated with CAD tools. These attributes are managed on a unique CAD – PLM integration. Now, if I want to use these attributes in the Part, I would probably get them navigating through the “Represented by” relation… Here the problem would be if I have two or three CAD solutions for the same item. Which is the master? These functionality of propagating property values, from my point of view, will be lost or have to be redesigned.

    Regards

    • Scott

      Thank you, Alfredo, I’m very glad you like the blog.

      Regarding your question, you bring up a good point. TC does actually flag one of the Representations as the primary representation (I forget the exact terminology, I’ll have to look that up later). By default the first design to be associated with the Part is the primary, but you can manually change that. The primary design is represented visually by a blue check mark next to it. Naturally there is a specific relationship type between a part and its primary design; I’d have to dig that up too. All that to say, I think you can reference that relationship in your attribute mapping and then your concerns would be addressed. However, I haven’t tried it myself yet.

      thanks again,

      Scott

  • http://www.plmconsult.nl Menk Slot

    Scott,

    What you also can do is make Engineering BOM (EBOM) and Manufacturing BOM (MBOM)

    Regards,
    Menk Slot
    http://www.plmconsult.nl

    • Scott

      Hi Menk,
      MBOMs are actually a different beast, and yes, they do get their own BOM. Still, I take the point that multiple BOMs should be investigated, although I’m not sure I see how they could resolve the differences between CAD and Part data.

  • http://www.facebook.com/jintawee.utenpitak Jintawee Utenpitak

    Hi Scott, I have some questions about choosing the item type in TC for CAD integration. Why almost all demos from Siemens PLM only use the standard “Item” to represent CAD instead of “Design” or “Part”?

    From my opinion, using the “Item” type directly might result in some difficulties later. For example, we will not be able to define the custom attributes specifically for it because those attributes will always be inherited by all sub item types.

    By the way, is it ok to define the custom item for CAD integration? There is very limited information describing how to properly use all the standard items which come with the OOTB installation and I am not comfortable with touching all these OOTB objects.

    • http://plmdojo.com Scott Pigman

      Just my guess, but: Part and Design weren’t in the TcEngineering data model and I presume that most demos were originally developed there. It takes awhile for the documentation to get updated.

      Personally, I wouldn’t ever use any of the out-of-the-box types (OOTB), I always subclass something, even if it’s just Item. That way I can make my customization to it without touching any to the OOTB types.

      I’ve never seen a problem with creating custom item types and CAD integration, although I’ve only worked with the NX and, to a much lessor extent, Pro-E integrations myself. We’ve use several different item types in our TcEngineering DB and plan on using several in TC 8.3 as well.

      There is limited information — and if you start to ask questions you might get multiple answers.

  • Dano

    Hi Scott,
    In one of your previous posts you mentioned that Siemens claims that in Teamcenter 9
    we will be able to create two different  item types using the same ID… this could be very 
    handy for creating Design and Part items with the same ID.
    Can you shed some light about this issue?  are there any official documents that mention it? 

    Thanks in advance,
    Dan 

    p.s – I really enjoy reading your posts! thanks! 

    • http://plmdojo.com Scott Pigman

      Hi Dan,
      I’ve addressed your question as best I can in a new post .

      And thank you for positive feedback, I really appreciate it.

  • Khiste Atul

    Hello Scott,

    This is a great post I am following, and I was working with this feature in Teamcenter 8
    I have got a question related to this CAD -EBOM (part) alignment.When we say publish data from structure alignment.There are some terms like Global association,transform,shape.What these terms represents.When I say publish data and make any changes at CAD design side,does it track or do the changes in EBOm ?

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  • Deepak Jain

    When you said opportunities for Automation,
    here what u want to say is that it needs a behaviour what windchill PLM have haves ??

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