Model-based definition: What, why, and a little how

Written By: Cat McClintock
  • 10/23/2017

Model-based definition (also known as MBD) is a hot topic these days in the product design and manufacturing world. More companies are beginning to implement it, which means more engineers (i.e., you) need to hop onboard the MBD train.


Why now? It’s partly because MBD saves time and prevents errors. Maybe it’s also because MBD proves really useful in additive manufacturing, where parts go straight from the computer to the printer. But most of all, it’s because the newest software tools, like Creo 4.0, have made it much easier to add MBD to the engineer’s tool kit.

If you’ve heard about MBD but aren’t sure about the particulars (or you’ve forgotten what you learned about it in school), you’re far from alone. We’ve heard many questions from design engineers about MBD, so here are a few quick videos that address the basics.

What is model-based definition?

According to the ASME, model-based definition is an annotated model and its associated data elements that define the product in a manner that can be used effectively without a graphic drawing sheet. That’s a fancy way of saying that you can share your 3D model with anyone involved in the design and manufacturing process, and it will contain all the information they need to build it.

In this video, Jennifer Herron of Action Engineering explains the differences between a number of terms that sound similar but describe different concepts: model-based definition, model-based design, model-based engineering, and model-based enterprise.

As a bonus, this video gives you a brief introduction to how MBD works in Creo 4.0. Spoiler alert: it’s really easy.

What is GD&T?

You can’t have MBD without GD&T, but what does that mean? Geometric dimensioning and tolerancing helps you communicate the full product definition to your manufacturing team, including the allowable amounts of variation that can occur during manufacturing. 

In this video, Sigmetrix CEO and President Chris Wilkes explains the basics.


Not complicated, right. If you add the GD&T Advisor extension to Creo 4.0, the software will do a lot of the work for you. It turns out that’s necessary in a world where most engineers think they are doing GD&T right, but also think almost everyone else is doing it wrong.

Why is MBD being implemented by more companies?

As Jennifer Herron explains here, part of the explanation comes from the increase in the use of additive manufacturing. According to Herron, “AM is the only method that requires a 3D model to produce it.” But AM isn’t the only reason to use MBD, as Herron notes.


How do you use MBD in Creo 4.0?

Ready to get started with MBD? This YouTube playlist includes lots of how-to videos that will tell you exactly what you need to know:

Now you know.

If you’ve watched these videos, you’ll sound extra smart the next time MBD and GD&T come up in a team meeting. And you’ll be prepared to lead the way when your company makes the shift to using model-based definition. Isn’t it nice to be ahead of the curve?

Download the Free E-book

MBD is quickly becoming the preferred approach to design as many of the hurdles to creating a single source authority model for every stage of product development are falling away. To learn more about model-based definition, check out the free e-book from PTC. You’ll find out more about the limits of 2D drawings, how MBD simplifies complexity, and where to get started. Download your copy today.

Download the free ebook

  • CAD
  • Retail and Consumer Products
  • Connected Devices

About the Author

Cat McClintock

Cat McClintock edits the Creo and Mathcad blogs for PTC.  She has been a writer and editor for 15+ years,  working for CAD, PDM, ERP, and CRM software companies. Prior to that, she edited science journals for an academic publisher and aligned optical assemblies for a medical device manufacturer. She holds degrees in Technical Journalism, Classics, and Electro-Optics. She loves talking to PTC customers and learning about the interesting work they're doing and the innovative ways they use the software.