When you think of modeling, you may think of features used when creating 3D geometry… or you may think of your days as a elbow model for L.L. Bean. You sexy beast. Either way, there’s a process and a need for both. In the case of 3D modeling, the process is dependent on what you need and often, how fast you need it.

Siemens has a unique approach to direct modeling as it relates to the history of features in both Solid Edge and NX. How do these programs stand out? And even more important, how do they approach the intracacies of modeling with and without a history of features? Kris Kasprzak, Director of Marketing at Siemens UGS PLM Software, had some things to say when faced with such a daunting question.

How does Solid Edge approach history-based and history-free direct modeling in parametric design?

Both modeling technologies (history and direct) have their place but are best suited for specific purposes. It’s not a matter of comparison, it’s a matter of positioning and when to use what. As most vendors are claiming, history is used for cases where a process is needed such as families of parts, where direct modeling is used for cases for parts where design intent is not well defined.

One market misconception is what parametrics includes. Because most systems are history-based, people tend to think parametrics, features, dimensions, relationships and history (a linear solve) are all dependent on each other. Most of these concepts are very powerful, however a history of features tends to be more applicable for parts where process matters—such as part families—and less so for unplanned change. Our approach (synchronous technology) does all the above without a history of features giving greater flexibility to edits and without the issues of complete model regeneration.

We (Solid Edge) chose a path to integrate both technologies into one system so users don’t need to choose which technology they use initially and can change later as process needs to be defined, or excessive change is needed. The power here is that if a part is started using ordered (history-based) features but edits outside the linear definition are needed, select features can be moved to synchronous. Geometric intent and dimensions are preserved but edits are not bound to the creation order. Features can drive features created earlier (holes can be moved that affect the “parent” shape” giving tremendous edit flexibility.

Thanks to Kris for these thoughts. Just to be clear on Synchronous Technology at this point in time. Solid Edge doesn’t allow going back and forth between keeping a history of features and working history-free. Currently, once you switch to history-free within Solid Edge, that change is permanent. However, their plan is to have a seamless transition back and forth between the two ways of modeling. In fact, all the CAD vendors are chasing this – Autodesk with Inventor Fusion, PTC with Creo and SolidWorks with Dassault’s V6.

To add some thoughts on Kris’ comments above… From a user perspective, history goes much deeper than needing it for a family of parts. Whether or not a design is defined, it allows a certain amount of control over the model and the options to create associations between parts, assemblies and sketches that would otherwise not be possible. History also allows for greater flexibility to change complicated parts.

Now, the ability to adapt a design does depend on if the model was started off modeled with history or with a history-free, direct approach. Still, in each program I’ve used, model complexity or, as Kris puts it, ‘excessive change’ lends itself better to a history of features and being able to control each feature. (I have a single part model, I can provide, which has never been able to be changed with direct editing.) Granted, I’m not an expert in all of them and would gladly and exuberantly enjoy being proven wrong.

To me, Kris’ reason against history is the very reason their Synchronous Technology is a great tool. It does give the user a choice between what to start with, because no matter which is used, the process that goes along with each, needs to be considered. It does help with families of parts, using similarity and being able to quickly make versions of a concept with specific regard to the process used to achieve the idea of an intelligent, parametric design.

Less confused?


Josh is founder and editor at SolidSmack.com, founder at Aimsift Inc., and co-founder of EvD Media. He is involved in engineering, design, visualization, the technology making it happen, and the content developed around it. He is a SolidWorks Certified Professional and excels at falling awkwardly.