Tips for Training Your Team on Model-Based Definition

Written By: Dave Martin
  • 11/18/2019
  • Read Time : 3 min
Teacher points to annotated 3D model in front of classroom.

You’ve made the decision to adopt model-based definition (MBD). Now it’s time to train your end users on what they need to know to document product and manufacturing information (PMI) directly in part and assembly models. Let’s take a look at key ideas they’ll need to understand to succeed.

Combination States

Combination states in Creo Parametric help you set up the visualization of your parts and assemblies exactly the way that you and others want to see them. A combination state includes one or more of the following:

  • Saved views (the model at a particular orientation and zoom level)
  • Cross sections
  • Explode states
  • Simplified reps (controlling which components are displayed)
  • Style states (displaying individual components as shaded, transparent, hidden line, wireframe, and so on)
  • Appearance states (different colors and textures for parts)
  • Layer states (for additional control over which entities are visible)

In MBD, though, combination states have an added purpose. We are going to display 3D annotations in our model. If we were to display them all in the default model view, it would look like “a bowl of spaghetti,” with a tangled mass of annotations and leaders cluttering the screen and model. It would be illegible. With combination states, you can determine which annotations are displayed, so they are readable and organized logically.

Your model templates should provide some initial combination states with a schema for the names of the combination states. These should include combination states for legal notices, a model map, model notes, datum feature symbols, and properties. Your end users will need to know how to create their own so they can organize model annotations.

Annotation Planes

Annotation planes define the orientation of 3D annotations in the model, but not the location.

Models come with several pre-defined annotation planes, including Front, Back, Top, Bottom, Left, Right, and Flat to Screen. You will create your own custom annotation planes, for example, on angled model surfaces.

In addition to the orientation, the annotation plane establishes the text direction (whether you are viewing one side or the other of the plane) and the text angle. The text direction and angle can be modified for individual annotations later.

Make sure your end users know that the location of the annotation is determined by the first reference selected when defining the annotation.

3D Annotations

Now that we have specified a combination state and an annotation plane, it’s time to add the PMI to our parts and assemblies. Most likely, your users already know how to create the 2D versions of these annotations. The transition to 3D simply means specifying the correct annotation plane and geometry references. These annotations include:

  • Linear and ordinate dimensions
  • Datum feature symbols (DFS), geometric tolerances, and datum targets
  • Notes
  • Symbols
  • Surface finishes

There are two big differences between 2D drawing annotations and 3D annotations for MBD: (1) created dimensions are sometimes easier to create than using shown dimensions, and (2) 3D annotations have geometric references.

For years, we told people if you build your models with design intent, at least 95% of the dimensions that appear on the drawing should come from the model. With MBD, though, created dimensions provide more functionality, like grouping them in features and designating control characteristics for process plans later.

3D annotations have geometric placement references, but users can add non-placement references as necessary. These annotations are “semantic,” or machine-readable. Coordinate measuring machines (CMM) would be able to use your MBD models to inspect prototypes, perform first article inspection (FAI), and support statistical process control (SPC) on production runs,

Next Steps

Now that you’ve documented your PMI in your models with MBD techniques, it’s time to share your models in your supply chain. There are three ways to do this:

  • Share the native Creo Parametric models.
  • Export a neutral STEP file using the AP 242 application protocol, which supports both 3D annotations and semantic references.
  • Publish a Creo View visualization.

There you have it: in a nutshell, everything that you need to get started training your users in MBD. For more information, please see the PTC University classes on Introduction to Model Based Definition with Creo Parametric, available in both instructor-led and web-based versions. Now start reaping the benefits of MBD!

Download the Model-Based Definition eBook.

  • CAD
  • Retail and Consumer Products
  • Connected Devices

About the Author

Dave Martin

Dave Martin is a Creo, Windchill, and PTC Mathcad instructor and consultant. He is the author of the books “Top Down Design in Creo Parametric,” “Design Intent in Creo Parametric,” and “Configuring Creo Parametric,” all available at He can be reached at

Dave currently works as the configuration manager for Elroy Air, which develops autonomous aerial vehicles for middle-mile delivery. Previous employers include Blue Origin, Amazon Prime Air, Amazon Lab126, and PTC. He holds a degree in Mechanical Engineering from MIT and is a former armor officer in the United States Army Reserves.