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SolidWorks is a favorite modeling software in medical 3D printing, with unique solutions ranging from dental implants to prosthetic limbs being brought to life using this innovative suite. If you are a 3D modeler with experience in the NURBS modeling process, you may be wondering if you can use SolidWorks to make creations using NURBS. SolidWorks does use NURBS—but that is not the process for which it is most well-known. SolidWorks is a modeling software specializing in parametric, history-based modeling, which differs from the direct, free-form surface modeling that has made NURBS a household name in 3D manufacturing. Although SolidWorks does not have a long history as a NURBS-based software, it has responded to consumer demand for surface modeling options. Starting with its software update in 2017 and for all subsequent versions, users have the option of solid modeling or NURBS-based surface modeling when creating objects within the suite. What is NURBS Modeling? Non-uniform rational basis spline (NURBS) is a mathematical model used in computer-animated design (CAD) to create precise curves and surfaces for various shapes within a model that may be later used for 3D printing. The advantage of NURBS modeling for medical purposes is that it allows for surfaces to be created that are not currently in existence. Its use of mathematical formulas to create curves and surfaces enables engineers to model unique and proprietary shapes; this is extremely advantageous when making objects such as custom prosthetics. What is Solid Modeling? Solid modeling—the process for which SolidWorks is named—is a parametric, or history-based, process. According to Kasten Marine Design, solid modeling assigns all its parts thickness and mass properties, along with parametric relationships to other parts in the model. As such, it is a much less “on-the-go” process than NURBS modeling. Solid modeling’s strength lies in helping engineers create complex designs by using a “logic tree” that establishes and preserves complex relationships among the various parts of the model. While it can be difficult for users to establish these complex relationships and form a logic tree before starting work on the model, the modeling process becomes infinitely easier once these relationships are created. With the proper model in place, creating complex products takes care of itself. For example, when modeling the forearm, an increase in the radius would automatically be accompanied by the appropriate shift in the ulna thanks to the relationship established in the logic tree. Does SolidWorks Use Both Solid and NURBS Modeling? The most recent iterations of SolidWorks use both solid and surface (NURBS) modeling. With advances in technology, SolidWorks is no longer confined to being a solid modeling software industry leader. Let’s look at some of the features modern designers can expect when using SolidWorks: Creation on Multiple Surface Levels According to Jeffrey Opel, professor of CAD/CAM and 3D printing at Tarrant County College, one of the most significant drawbacks of previous versions of SolidWorks was the inefficiency in creating surface-level geometry on shapes other than spheres or cones. Now, surface geometry can be created in a few simple steps using the wrap feature, which allows you to drag along the desired NURBS points, drop the points once the desired curve is created, and project the geometry to the object's surface. Offsetting 3D Curves SolidWorks users' ability to offset a curve on the surface to create a unique inlay is another strong feature of the latest versions of the software. These offsetting 3D curves can be used to create raised and layered objects. Solid Modeling vs. NURBS Modeling Although many contemporary 3D modeling suites, including SolidWorks, will have solid and surface modeling capabilities, it is important to contrast these two primary forms of 3D models to have a clear understanding of when to use each for medical purposes. In general, the solid models that SolidWorks is known for have the following characteristics: All parts of the model have a thickness and are assigned mass properties Operation in a history-based environment that requires the planning of features, constraints, relationships, and dependencies within the model A historical genesis, or logic tree, is maintained so that changing one of these predefined parameters changes all related and dependent portions of the model Direct changing of the model will also change the underlying constraints that guide the model Surface modeling, on which the NURBS process is based, will have a different set of characteristics, including: The use of zero-thickness surfaces that have no mass properties Operation in a direct, free-form environment, in which a more flexible manipulation of the model is made possible without being tied to predetermined constraints When constraints are created, they do not affect the user’s ability to drag, pull, or otherwise manipulate other parts of the model Based on these differences, solid modeling is best for designers who want accuracy and precision in replication. In contrast, surface modeling is best for those professionals who wish to have the creative freedom to design something completely new. Both functions are relevant to the medical field, making the updated SolidWorks a strong modeling software choice. How SolidWorks Can Benefit a Medical Modeler From start to finish, the combination of solid and NURBS processes available in SolidWorks provides practitioners with a unique blend of flexibility and precision when modeling medical implements. These capabilities make SolidWorks a valuable tool for practitioners, along with several areas in 3D medical manufacturing. Design and Engineering The SolidWorks platform allows teamwork and collaboration among many designers. It also allows for feedback from management and shareholders. Using NURBS curve creation, engineers can quickly put new ideas into motion and layer and build upon 2D sketches. The solid modeling framework also lets the team quickly reproduce successful projects and keep new updates on a scale. Manufacturing and Production Files from SolidWorks can be extracted into several formats to ensure compatibility with a wide variety of machine printing devices; this allows for maximum efficiency and precision during object creation. Service and Management SolidWorks software allows engineers and practitioners to test their working products against the models. If the device is not functioning as planned, users can go back into the model and see which elements of the design affect operations and service these areas to improve future prints. The software also gives the user information as to how to maintain the printed objects properly. Marketing and Sales One of the most powerful aspects of SolidWorks is its capabilities in marketing and sales. Professionals can pitch proposed devices to customers while still in the model phase; this gives clients the chance to view the product in action beforehand. The software can also use NURBS processes to make customized changes based on feedback received during the sales process. Editing and Continuation Using NURBS processes, the user can make changes to the current design without disrupting the overall model. If the product is successful as-is, duplicates can quickly be created or scaled to new dimensions. Below is a good video on Solidworks modeling for medical product design: Conclusion Although SolidWorks is not known as a NURBS platform, the most recent iterations of the software allow for surface modeling that uses NURBS concepts. Therefore, when purchasing the updated software versions, users can expect to have both the solid modeling capabilities—for which SolidWorks is named—and the surface modeling functions characteristic of the NURBS process at their disposal. The solid modeling capabilities are useful when building objects that require relationships and constraints between parts, while NURBS is more open and free-flowing to allow engineers creativity when making proprietary designs. Click the following link to read about NURBS vs Polygons.