Edited by Leslie Gordon
I have not seen anything as exciting and innovative since the introduction of parametric modeling in the late 80s. Called “synchronous technology,” the scheme extracts information from the kernel, the 2D and 3D solver, and design commands in the CAD program to localize the impact of an edit. Instead of ordering features in a history tree, the software just collects them. This eliminates the typical problems when editing history-based models that come from difficulties in understanding relationships buried in the history tree.
For example, when users execute a drag or dimensional edit, the synchronous technology queries other application layers in real time to account for existing geometric conditions, user-defined equations, parametrically driven dimensions, and so-called “procedural features.” These are special features such as holes, patterns, and thin walls that allow parameterized edits without model regeneration. (Parameters for holes, for instance, include size, type, depth, and threads.)
After the technology gathers all the necessary data, a function called Live Rules automatically maintains the so-called “strong” or obvious constraints such as parallel, concentric, tangent, and coplanar. The idea is that obvious constraints such as a tangency, for instance, should almost never be broken, so why burden users with enforcing them? Live Rules frees designers to make models without such embedded constraints because it discovers and resolves geometric conditions throughout future edits.
Live Rules is also important in direct modeling, letting users change groups of elements, en masse. For example, suppose you import a model where the original intent was to keep the supports that span the width on the same plane. Though this relationship was lost in translation, once you select a particular face, Live Rules finds all the coplaner faces. All it takes is a face selection and move operation to make the entire series of ribs move.
Editing the mounting holes of a pillow block is another good example. Suppose you need to move the holes further apart to meet a mating condition. A constrained system would keep you from operating directly on the holes until you changed the “parent” geometry in this case, the base of the pillow block. This method is unwieldy at best. In contrast, synchronous technology lets users just place a dimension between the base holes to drive the movement directly. Again, the technology maintains all the strong conditions such as tangencies and concentricities.
In general, users can apply dimensions directly to the 3D model and alter it in different ways. One is through dynamic 3D driving dimensions. Users can directly edit these and also change them by external edits such as face moves. Next is through fixed 3D dimensions. Users can directly edit these, but cannot make any external changes. Last comes equation-based 3Ddriving dimensions. These only let changes be driven from some other dimension. For example, a hole might remain centered on a base because of a user-defined equation placed in the Variable Table.
For another illustration of how synchronous technology works, take the example of editing a plastic thin-wall component, in this case a two-part housing for a saber saw, the back side of which has hundreds of features. In a traditional system, making a slight change to the radius of the blend on the back side of the component would necessitate a complete regeneration of the part, because the history-tree must replay step by step. This change might take about a minute to complete. But synchronous technology handles it in 2 seconds. That’s because the technology only performs localized computes, capturing dimensions and parameters as needed, rather than regenerating every element that preceded the changed element. The unique solver in synchronous technology performs bidirectional edits in real time and so eliminates the need to preplan for future changes.
Another notable function in the software is a “steering wheel” that lets users modify geometric elements with drag to move, rotate to add taper, select a direction to move, and align to geometry operations. And users can now sketch directly on faces. Instead of using design features for pockets and bosses when they are not needed, simply draw a sketch on an appropriate face and remove or add material. This method is faster and simpler, and it requires fewer steps.
This version of Solid Edge really shines in a multi-CAD environment, where typically models lose their history trees when transferred. Once foreign native data is read into the program, the software treats it much like an inherent built-in model. Imported models come in as a single body, but Solid Edge can operate on them to recognize geometry, build geometric relationships, and move and edit directly on the model, just as it does with its own data.
The software comes from Siemens PLM Software, 5800 Granite Pkwy., Suite 60, Plano, TX 75024, (972) 987-3000, siemens.com/plm
Ray is president of TechniCom Group LLC and its principal consultant and editor. His firm specializes in analyzing MCAD and PLM systems and has reviewed and compared such software since 1987. Ray can be reached at [email protected].