In NX you can change the design mode between history and history-free, however, due to the differences between the two modes, data unique to each mode is removed when the mode is changed. For example, when changing from history mode to history-free mode history data is deleted, including feature data. Geometry remains in its current state but features are removed, similar to using the Remove Parameters command. However, features that are local features are retained, so features such as holes and blends remain as holes belnds, but become local features.
Specific synchronous modeling commands are used to modify a model, regardless of its origins, associativity, or feature history. A model can be imported from other CAD systems, neutral formats (IGES and STEP), non-associative, with no features, or it could be a native NX or Solid edge model with features. Synchronous modeling lets you use parametric features without the problems arising from feature history by working directly with a model that virtually eliminates time spent rebuilding or converting geometry. In short, if you have a parametric model that you want to edit quickly, use synchronous techniques in history mode.
In either history or history-free mode, you can select a complete set of features regardless of whether they are parametric features or order-independent local features created in history-free mode.
Synchronous modeling has been somewhat controversial since it was first announced and has endured considerable scrutiny by a broad spectrum of people. There is still no consensus on synchronous modeling, but everybody seems to have an opinion - some well-founded, some misleading. Its implementation and capabilities in NX have become more comprehensive over a relatively short period of time.
While synchronous technology has received a lot of attention, Siemens PLM Software, was hardly the first to promote the benefits and advantages of a non-history-based design approach with synchronous technology. Siemens joined the ranks of Kubotek, CoCreate, IronCAD, and SpaceClaim who had already embraced it. However, Siemens' take on the approach was quite different than the competition - it's a lot more than direct modeling, or more precisely, direct model editing.
Synchronous technology provides non-history based direct modeling capabilities, but it also provides the ability to employ dimension- and constraint-driven modeling. It is the combination of all of these capabilities that sets Siemens PLM Software's synchronous technology apart from the competition. Synchronous technology will likely benefit users in the following areas:
- Initial designs can be created quicker without having to concern yourself with pre-planning the design process for creating features
- Design changes are quicker because there is no history tree
- No history tree is a handy capability in a multi-CAD environment
- Without a history tree that can be restrictive, mechanical design can be easier to learn and better suited to “casual” users, as well as “full-timers.”
In NX, assembly part files point to geometry and features in the subordinate parts rather than creating duplicate copies of those objects at each level in the assembly. This technique not only minimizes the size of assembly parts files, but also provides high levels of associativity. This enables a user to modify the geometry of one component so that all assemblies that use that component to automatically reflect the change. These relationships not only affect assemblies, but also other associated objects, such as drawings, tool paths, and CAE meshes.
There are different approaches to assembly modeling and with NX you are not limited to any one method. You can create individual part models, and then add them to assemblies later (bottom-up), or you can create parts directly at the assembly level (top-down assembly creation). Additionally, you can start by using a top-down method, and then switch back and forth between bottom-up and top-down modeling, depending on your specific needs. It is this versatile approach that helps NX fit into a wide variety of workflows.
An assembly can contain a mixture of parts modeled with history or history-free mode. This is not actually new. Even prior to NX 6 this combination could be used. If you import a Parasolid .x_t (or other) part into a NX part file it has no history. This part can coexist in a NX assembly with native NX parts complete with features and history. Also, an assembly can contain a mix of parts and JT files, so if you are working with a supplier or OEM who provides only lightweight data for building an assembly, you can reference JT data and build models that are the correct size and shape.
Geometric changes made at any level within an assembly result in the update of associated data at all other levels of affected assemblies. An edit to an individual piece part causes all assembly drawings that use that part to also be updated. On the other hand, an edit made to a component in the context of an assembly results in the update of drawings and other associated objects (such as tool paths) within the component part.
By itself, NX has been a very capable MCAD application for a number of releases, and synchronous technology and modeling techniques make NX 7 another significant release. Out of the box, the core package is well-rounded and versatile, and there are a large number of optional modules available for handling virtually aspects of CAD, CAM, CAE, and PLM. NX 7 is one the most comprehensive packages out there, with “heavy duty” solvers and a user interface that continues to improve. The continuing improvement of synchronous modeling and the range of optional modules make NX 7 a good choice for complex mechanical and mechatronic design that you are unlikely to outgrow. As your designs mature and evolve, NX will keep pace moving forward. NX is available in different groupings, such as CAD, CAM, CAE, etc. for different purposes, although obviously they can be mixed and matched as needs dictate.
So, is synchronous technology the Holy Grail for 3D CAD systems? I don't think I'd go quite that far, but synchronous technology continues to look very promising as an evolving development changing the MCAD landscape.
The Week's Top 5
At MCADCafé we track many things, including the stories that have attracted the most interest from our subscribers. Below are the five news items that were the most viewed during last week.
Tech Soft 3D Reaches Agreement With Adobe to Develop Adobe 3D SDK Technology
Tech Soft 3D announced that it has signed an agreement (subject to certain closing conditions) with Adobe Systems to transition development and support of Adobe's 3D SDK and related technologies, and associated employees and resources to Tech Soft 3D. Consisting of a 3D CAD translation suite and PDF publishing SDK, the technology allows OEM development teams to create applications that access data from over 25 3D file formats, and publish rich 3D PDF files in the PRC and U3D formats. Adobe will continue to support viewing of and interaction with 3D data within its applicable products, including the free Adobe Reader. Moving forward, Tech Soft 3D will continue to make updated CAD translators available as plug-ins to applicable Adobe software for reading and outputting 3D PDF. For easier application integration, Tech Soft 3D plans to immediately repackage the 3D SDK and PRC publisher into pure library form. Tech Soft 3D has been a key Adobe reseller to the engineering software community for the Adobe PDF Library SDK since 2005. In 2008, Tech Soft 3D was named a distributor of the Acrobat 3D SDK for OEM integration of Acrobat software's 3D capabilities into CAD/CAM/CAE software.