Model-based confusion in 3D CAD and PLM

Model-based confusion in 3D CAD and PLM

Bad terminology is an enemy of good thinking. A running joke in PLM industry says that if you ask what is PLM in a meeting room, the number of answers is usually greater than number of people. PLM industry has a big terminology problem. It is hard to agree and to find common definition or even just a agreement about some terms. Three letter acronyms and other fancy terms are flying around when you get close to the rooms with PLM discussions and meetings.

One of the most recent terminological confusion for me was extensive usage of “model-driven” terminology. It sounded like something important and the thing that can bring a difference. Few weeks ago at CIMdata industry and market forum, I captured the following slide:

I found CIMdata PLM glossary here and it can provide more information about terminology. Check it when you have some time.

The extensive use of “model-base” caught my special attention. I can see this trend for the last few years. Model-based tools and approach as promoted by PLM vendors and evangelists.  I’ve been trying to understand what does it mean. Is it something different or another marketing buzzword?

Jos Voskuil article –  Why Model-based? The 3D CAD Model was my next stop to clarify model-based trend. Jos is making an interesting difference between 3D CAD and 3D CAD Model. Here is the passage:

At the time 3D CAD was introduced for the mid-market, the main reason why 3D CAD was introduced was to provide a better understanding of the designed product. Visualization and creating cross-sections of the design became easy although the “old” generation of 2D draftsmen had to a challenge to transform their way of working. This lead often to 3D CAD models setup with the mindset to generate 2D Manufacturing drawings,  not taking real benefits from the 3D CAD Model. Let’s first focus on Model-Based Definition.

Model-Based Definition: We talk about Model-Based Definition when the product and manufacturing information is embedded / connected to the 3D CAD model, allowing the same source of information to be used downstream for manufacturing, analysis and inspection. The embedded information normally contains geometric dimensions, annotations, surface finish and material specifications. Instead of generating easy to distribute 2D drawings, you would be using the 3D model now with its embedded information.

So, model-driven is about embedding and connecting information to 3D CAD models based on Jos’ explanations.  For many years, PDM and PLM tools used CAD data is source of engineering and product information to be used in building processes to be used in downstream processes. PLM tools presented a value of 3D collaboration, information sharing and many other features and tools to leverage 3D models without conversions to 2D drawing together with information stored in PLM databases. Some MCAD  tools such as CATIA, Creo and NX became integrated and provided a rich functional features set together with PLM systems provided by the same vendors. Sometimes, it is even hard to draw a border between CAD and PLM offering by large PLM vendors.

Here is the thing… I don’t see much difference between saying PLM-CAD integration sharing data and information for downstream processes and “model-driven” data sharnig. It might be a terminology thing, but data is managed by CAD-PLM tools today and accessed by people and other services. This is how things are working today. If model-driven is an approach to replace 2D drawings, I can see it. However, 2D replacement is something that I’ve heard 20 years ago. However, 2D drawings are still massively used by manufacturing companies despite some promises made by CAD vendors long time ago. But this is a different topic.

What is my conclusion? “Model” is a great and powerful word. But as many others terminology and TLAs in a complex PLM world is overused and can be confusing for people looking for technology value and differentiation. I can see Model-based marketing is providing explanation such as “model… is an approach to use model”. It reminded me old definition of PLM as a “tool to manage product lifecycle”. I’d like to see PLM industry focus on how to provide definition explaining value of products and not hiding behind confusing buzzwords. It seems to me in most cases “model-driven” is used to explain that information is stored in 3D CAD systems and databases and is used in product development processes. But hey…  that was an idea of PLM from the beginning. So, we are still good, even if we switch to “model-driven” approach. Just my thoughts…

Best, Oleg

Want to learn more about PLM? Check out my new PLM Book website.

Disclaimer: I’m co-founder and CEO of OpenBOM developing cloud based bill of materials and inventory management tool for manufacturing companies, hardware startups and supply chain. My opinion can be unintentionally biased.


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  • I think Oleg you missed the point of model-based by focusing and quoting on only one aspect. I was planning to publish this weekend more info related to model-based systems engineering (another dimension of model-based). But I will first clarify your misunderstanding

  • beyondplm


    It is possible that I missed something. I look forward to your blog.

    What I didn’t miss is that MBD stands for both Model-based design and Model-based definition, which by itself is very confusing.

    MBE (engineering) and MBD (design) are different. However, MBD reminds 3D CAD because it uses 3D Model. And MBE very much similar to PLM, because it uses models to define technical system for multiple disciplines and across full lifecycle. The only practical difference is that model based approach will use 3D (models) and not 2D drawings.

    Have a good weekend writing!

    Best, Oleg

  • Thanks Oleg for the drive to publish – never a dull weekend 🙂 I started my blog series two weeks ago to create clarity – hard to do it in blog style – I am now at post 2 out of 5 potential. Happy reading after the weekend

  • Ilan

    I guess you are right about the confusion around it. In my way of interpreting it, Model based design, in an overly simplified terms, is a way of saying put all your GD&T on the 3D and avoid generating drawings. I agree that by itself it has no significant value other than maybe save drawings’ drafting time from designers and engineers.
    Model based enterprise is an enterprise (not just engineering, but also downstream disciplines) that is geared towards 3D based manufacturing. For example the people in the shop – welders, machinist, etc. have the systems and are trained to build off of 3D. Buyers that work with 3d cad driven EBOM rather than reading BOM tables from tables, QMS folks who can read dimensions based on the 3D reports, etc.
    Model based system engineering is what completes the picture for me. A true model based process is not just based on design. It is the complete logical-functional-physical-simulation that drives a more efficient and shorter cycle manufacturing process.
    The reason it has not been absorbed yet is a) drawing have been around for ~200 years, b) people/cost of training for smaller companies especially, c) luck of vision and understanding of the value behind it, and d) technology was lagging up until few years ago, I think. With new era of engineering and open minded millennials, improvements in technologies it may change. Time will tell.
    Just my two cents.

    Ilan Madjar (xLM Solutions –

  • beyondplm

    Hi Ilan

    Thanks for sharing your insight and comments. 2D to 3D revolution was promised 20-30 years ago (at least), but it didn’t happen. And even today, new CAD systems such Fusion360 and Onshape are prioritizing their investment into 2D drawings – you can see it by multiple comments and articles on their forums. So, although full 3D is a nice vision , the ugly truth in the shop is different.

    A second aspect of model-based is another way to do PLM marketing without saying bundle of CAD and PLM. You can think about it as a nice way to say “model is started in CAD and enhanced with all information in PLM system”… model-based. It is a nice attempt and it is better than to say – you need PLM backbone to run CAD system, but it is very confusing.

    Best, Oleg

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  • oops

    Seems like marketing-driven terminology to me.

  • beyondplm

    You’re right. And I think, it should not be that way. “

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  • The post is good and easy to understand. Just in case you seem to be selling and promoting. But that’s ok too.

  • Oleg (test)

    What am I selling?

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