Like a fashion model who is also a member of MENSA, 3D computer-aided design supports the argument that first impressions never tell the whole story. Frequently people are so enamored with the 3D visuals that they forget to look deeper for the real value of this approach.

3D technology has played a major role in the revolutionary developments that have taken place across design and manufac-turing during the last decade. But there is more to 3D design than its visual capabilities and its opportunity for bringing more ideas into the design process. The use of 3D methods also affects what happens after the input of product ideas is completed and strategic opportunities occur, particularly in the area of product quality. To fully benefit from its potential, product designers must look beyond the surface of 3D.

The quality of design

Fig. 2. This example illustrates the ease of making changes with dynamic modeling. Each image shows a major modification executed directly on the geometry in a single modify command. 1. Moving all selected bosses down against the extrude. 2. Changing only two selected blend radii while keeping the shell thickness. 3. Offsetting four selected walls to be thicker than the shell. 4. Stretching the part and moving a single boss with a click and drag.

Whether new appliance plans are drawn, drafted or modeled, much of a product’s quality is determined during design. Although any good development department constantly works to identify and resolve design-centered quality issues, sometimes issues remain hidden, surfacing only during late-stage prototyping or, worse, during manufacturing ramp-up. Even more regrettable is when issues emerge later, in the field, where the costs to service departments and to the company’s reputation can be astronomical. 3D product development’s strength lies in eliminating this risk and waste.

Companies that see the result of 3D design as only automatically generated 2D drawings are missing the point. Rather than considering a 3D model as a step above a 2D drawing, designers should view it as a different, and better world. A 3D computer model is so lifelike that companies can apply quality control measures to the virtual model more effectively than they used to do with a physical model. These test applications in the virtual world are easier, faster and cheaper to execute. In addition, the tests themselves are more comprehensive and better able to identify problematic design aspects.

One example is prototyping. A perfect prototype is often the final milestone before a product moves from design into production. It ensures that all sub-assemblies fit together without conflict, that moving parts function correctly and that manufacturing engineers have a mockup to work from to create assembly sequences.

However, the path to a perfect proto-type is inherently iterative. Traditionally, a series of imperfect prototypes might be created to work out problems before the design is finalized. In designing a product in 3D, the expense and time for-merly associated with multiple physical prototypes are eliminated by storing iterations inside the computer. Because 3D models can be assembled and ani-mated, an entire product can be perfected for proper clearances, tolerances and interference before the physical product is built. Motion can also be simulated to evaluate the working behavior of moving parts.

Another example is testing for real-world conditions. A product’s casing, for example, must be durable enough to protect the device from stress or strain. Fabricators build a physical prototype, and product testers place the case under the physical conditions the product might expect to experience. If the prototype breaks, it means back to the drawing board to find a more suitable material or thickness. With 3D design, however, products can be tested under the same working conditions, including stress, displacement and heat. Also, a much broader range of materials can be tested without ever leaving the computer desktop.

There seems to be no limit to the kind of simulation that can be applied to 3D data, whose mathematical attributes can comport with even highly special-ized simulation programs developed by researchers. More common needs of computerized product testing are now satisfied with software modules that plug into the solid modeler itself. For sheet-metal fabrication, a bend deformation module will affect the shape of the 3D model the same way fabrication tools affect the material. If a punch is planned too close to an edge, the metal buckles on the screen. A designer can then immediately change the location of the punch in the 3D model, without wasting time or materials. Similarly, mold analysis will predict flaws in molded plastic as it hardens, thus enabling the cost-effective manufacture of designs with more complex curves.

Due to the development of 3D simula-tion applications, many companies can eliminate iterative physical prototyping and spend those precious dollars only one time — during the final prototype stage The ability to archive dozens of design cycles within the computer saves an immense amount of money, considering that a physical prototype might cost as much as $10,000. The timeline spanning idea conception to factory reproduction has also shortened to what was previously considered impossible. 3D design and simulation can replace much of the work that used to be done through physical test batteries. In this way, 3D CAD ensures a higher quality product.

The fork in the road

Some companies consider the various 3-D systems to be essentially the same. In reality, there are two distinctly different approaches to 3-D product development: history-based (sometimes known as feature-based modelers), and the history-free method of dynamic modeling. Each approach is applicable to different types of companies.

In time-pressured industries, a design issue might be noticed at the last minute before production starts, a small suggestion to improve the quality of the appliance might be proposed or a feature might be added based on a competitor’s actions in the market. For a complex part, it might take days or weeks for someone to research how a part was made in a feature-based modeler, and then reconstruct the model to incorporate the change. All the while, factory equipment sits idle, and product revenues are delayed. With a dynamic modeler, the change can be made directly within minutes or hours.

Product development that demands real-time response to new and changing information is particularly well suited for dynamic modeling. These fluctuating conditions can quickly tangle a history tree because they represent change that wasn’t planned during design.

A dynamic-modeling approach excels for companies confronted with frequent or unpredictable change, or for products with short development cycles. Dynamic modeling is history-free and creates a free-form design environment that rapidly creates products with all the precision and power expected of a 3D system. The strengths of dynamic modeling are also well aligned to companies that leverage lean principles in their development process.

Take, for example, waste reduction. Design-data management systems directly support the principle of design reuse by not redesigning a product or part that’s been created before. This eliminates the waste of duplicative effort. But design reuse isn’t just about finding what already exists. It’s also about repurposing what already exists into the next generation of product.

This is an area where dynamic modeling dominates. History trees are similar to software programs in that they don’t work if you cut the instruction code in half. Dynamic modeling, however, lives in a world of geometry, which allows an existing product to be cut in half any way the engineer desires, and then easily morphed into the next-generation product. Because engineers won’t have to start from scratch on new product development, companies gain a significant head start on development and can shave weeks or months off of projects.

Sharing without limitations is another benefit of dynamic modeling. Interoper-ability problems can create a lot of waste during the development phase, when models must be re-created rather than carried forward. Geometry is the only common element across all 3D systems. Because dynamic modeling thrives in a geometry-based world, it can import data from any other 3D system and work with it, eliminating the waste normally associ-ated with a lack of interoperability.

Equally important is that any member of the design team can pick up a design and make changes without having to know the history behind the series of steps taken to create the model. With dynamic modeling, a shape is a shape is a shape, and the user can focus on the result of design in form, fit and func-tion. It is not uncommon in companies that standardize designs with dynamic modeling for engineers to pass models around the team for each other to work on during development. This is the dif-ference between a design team and true “team design.” The latter eliminates resource bottlenecks, brings different perspectives to bear on problems, and fosters innovation and creativity through collaboration.

These are just some of the reasons why dynamic modeling is described as a for-ward-looking design process.


For more information email: Todd_Black@CoCreate.com