Synchronous Technology—Debunking the Myths

A look at history-based modeling, history-free modeling and the myths associated with synchronous technology.

As a CAD manager, I have gained some experience with Solid Edge and synchronous technology through my team using it on specific client projects. As a freelance writer, I’ve been researching, reviewing and writing about Solid Edge for around four years now, and have even had the opportunity to attend Solid Edge University. So, I was excited to be given the opportunity to take a look at a few of the main “myths” associated with Solid Edge and synchronous technology to see if I could debunk them. In researching for this article, I also had the opportunity to ask Matt Lombard of Siemens PLM Software some questions directly as well as reference his e-book Solid Edge with synchronous technology—Steering a new course in 3D design.

Synchronous assemblies make it possible to use both synchronous and ordered parts in the same assembly. (Image courtesy of Siemens.)

Synchronous assemblies make it possible to use both synchronous and ordered parts in the same assembly. (Image courtesy of Siemens.)

Some of the main synchronous technology myths we’ll be looking at in this article are:

  • You can’t have the best of both worlds—The notion that history-based modeling and history-free modeling are the only two choices for modeling in 3D.
  • It’s one or the other—The idea that you can’t use synchronous technology in conjunction with history-based modeling and history-free modeling.
  • It’s too difficult—It would be difficult and time consuming to learn or retrain yourself or your entire staff on a new technology such as synchronous.
  • Certain features or techniques behave better when you are using ordered modeling—The idea that some features or modeling techniques lend themselves better to history-based modeling.
  • Featureless 3D models are “dumb” models—The notion that any models without a feature tree are “dumb” models and that they can’t be changed or revised.

You Can’t Have the Best of Both Worlds

Probably one of the biggest myths associated with Solid Edge and synchronous technology is the notion that there are only two ways to create and edit 3D models in CAD software—history-based modeling or history-free modeling. That myth, however, couldn’t be farther from the truth and in fact it’s one of the main reasons that synchronous technology was invented: to give CAD users the best of both worlds.

History-based modeling has been seen by many as the most popular modeling method for quite some time. On the one hand, history-based modeling does have powerful features such as being dimension driven, highly automated and feature based. On the other hand, though, it does have drawbacks. Features that users create are totally dependent on the previous features that were created. Since features in history-based modeling are stored in a linear tree, any changes or additions to features means that the entire feature tree needs to be regenerated, which can take a lot of time with large files or assemblies. Users also spend a lot more time preplanning how they will go about creating and adding features to their models to keep their design intent intact if changes are required down the line. In addition, some unexpected changes may affect the model so much that constraints, faces and other features can fail by being lost or broken, thus requiring rework time to recreate the features in a way that ensures that they behave properly with the new changes.

History-free modeling, sometimes also referred to as direct modeling, has gained followers due mainly to its ease of use and flexible editing capabilities. While changes to a model may be easy, history-free modeling lacks any parametric capabilities. Not having any parameters, constraints or relationships in your models can negatively affect your ability to retain your design intent as you make changes throughout the life of your project.

Synchronous technology, however, capitalizes on some of the best principles of both history-based and history-free modeling while leaving some of the more undesirable traits behind. In addition, synchronous technology also has some features that you won’t find in history-based and history-free modeling.

The most powerful and desirable features from history-based and history-free modeling—such as dimensionally driven, highly automated, feature-based, flexible and fast editing, along with ease of use—are all incorporated into synchronous technology.

In contrast to history-based modeling, however, synchronous technology features are stored in a collection as opposed to a sequential tree. This means that when changes are made, the model is solved all at once (thus, the term synchronous) as opposed to feature by feature. This means that far less model regeneration time is required when making changes and additions.

Unlike history-free modeling, synchronous technology allows you to continue to use features and design-driving parameters, constraints and relationships by using its own set of tools, such as feature recognition, intent recognition, Driving Dimensions, Face Relations, Synchronized Solve, Procedural Features and the Steering Wheel.

An illustration of how synchronous technology combines history-based and history-free modeling. (Image courtesy of Siemens.)

An illustration of how synchronous technology combines history-based and history-free modeling. (Image courtesy of Siemens.)

It’s One or the Other

Another misconception or myth I have heard reluctant users talk about is the fact that they think once they start to use synchronous technology, they are locked in to only using that and are unable to use history-based or direct editing methods where appropriate. In Lombard’s e-book, he explains how Solid Edge allows you to combine synchronous technology and history-based modeling in both parts and assemblies. So while you can use one method or the other independently if you desire, Solid Edge gives you the freedom to use both. This works at both the part and assembly level; they both can use synchronous, ordered or both. In asking Lombard to expand on this myth, he replied, “In fact, we encourage people to mix methods. Sync and ordered have different strengths. Sync is best at editing prismatic models; ordered is best at driving associativity and sketch-based features like extruded text. A mixed-mode model winds up with the synchronous body first, then the ordered features following. Synchronous edits allow the ordered features to recalculate.”

A view of a model using a mix of synchronous and ordered methods. (Image courtesy of Siemens.)

A view of a model using a mix of synchronous and ordered methods. (Image courtesy of Siemens.)

It’s Too Difficult

When I first started to get involved with Solid Edge and synchronous technology, I had plenty of reservations. I thought it would be extremely difficult for me and my staff to learn an entirely new methodology for 3D modeling. In addition to thinking it would be difficult, I knew we still had projects going on that needed to get done and sent out—where would we find the time to learn synchronous technology? That myth started to get debunked for me when I attended Solid Edge University in 2014. On day one, I attended a breakout session where Melissa Schultz of Curt Joa discussed how her team of 70-plus users were able to successfully make the move to synchronous technology. Schultz explained that this was in part due to the new features focused in synchronous, the benefit of smaller file sizes and the ability to have ordered and synchronous in the same file. She explained that the final key to the successful migration was a well-thought-out and executed training plan with support from a value-added reseller. In talking with Lombard, he said that he was familiar with that case study and added that “The big thing I took from her presentation was that the guys involved were able to do more refining to the design because they wound up with more time available compared to using ordered.” This definitely helped debunk that myth for me. Lombard does give the following advice in his e-book, though: “When learning Solid Edge, it is best not to expect it to work exactly like some other system. The general concepts are usually familiar to users of other software packages, but the details of how you accomplish specific tasks are often different. Terminology is often unique to each system as well.”

Certain Features or Techniques Behave Better When You Are Using Ordered Modeling

This is one myth I was unable to debunk. I knew that Lombard knew more about this one than I did, but even he responded, “Yes, this is true to some extent. Some types of features, especially in sheet metal, aren’t available in synchronous because they need a sketch, like extruded text. Editing text as if it were geometry would be TEDIOUS, so that’s an ordered function. Fillets can work either way, but if fillets consume too many faces, they can make synchronous features fail. For that reason, we recommend applying rounds as ordered features.” In the end, though, that is why it’s so powerful that you are able to use both methods on any given parts and/or assemblies.

Featureless 3D Models Are “Dumb” Models

Finally, one of the last myths I’ve heard over and over is that if a part or assembly model doesn’t contain a feature tree, it is essentially a “dumb” model and can’t effectively be changed. I knew this wasn’t the case, but Lombard was able to explain, “Ordered users refer to imported models without any ordered features as “dumb” models because they can’t change them. Synchronous can change these models, and they are far from “dumb.” In fact, synchronous can add intelligence to certain imported features and change them parametrically, like holes or a pattern of holes. Also, if you apply dimensions or PMI (product manufacturing information), you can use those dimensions to drive the size/position of features on the model. And the dimension itself can instantaneously change the way they drive the design intent in ways that would take several minutes of complex operations to edit in ordered mode.”


I think it’s easy to see that the majority of the myths I mentioned above are fairly easy to debunk. Synchronous has a lot of advantages and brings a lot of power to the table when both creating and revising 3D models. Synchronous allows you to save quite a bit of time, and we all know time is money. I wanted to conclude with Lombard’s thoughts on some of the biggest advantages of synchronous technology:

  • Ease of editing—You can create design intent as you need it.
  • The ability to kill rebuild time—One of the biggest time wasters in the whole design process.
  • The ability to kill associativity—Most people remove associativity at the end of the process because it’s scary. Why not just avoid it altogether until you need it? And this is where design intent on the fly comes in. You can edit multiple parts in an assembly at the same time without creating any sort of relationship between them.
  • The real advantage is that this isn’t an either/or scenario; you can use both. If you really need associativity between parts in an assembly, you can create that with ordered features. If you only need the association for a single edit, do it synchronously, and there will be no lasting effects.

I would like to thank Matt Lombard for his time and input on this article. His knowledge about Solid Edge and synchronous technology, as well as the information I was able to glean from his e-book, were indispensable while writing this article. I would highly recommend that anyone who is looking to learn more about Solid Edge and synchronous technology check out his e-book. Not only does it contain a wealth of information on the software and technology, but it is also filled with examples, tutorials and all kinds of productivity tips.

Siemens PLM has sponsored this post. They have no editorial input to this post. All opinions are mine. —Jeffrey Heimgartner