The Future of 3D Mechanical Design

Excerpted with permission from  

March 8, 2004

Last month, CAD/CAM Publishing organized a panel session at the National Design Engineering show bringing together the operational leaders of five CAD/CAM-development organizations:

• Michael M. Campbell, Vice President of Product Management, Parametric Technology Corporation

• Charles Grindstaff, executive vice-president of PLM Products, UGS PLM Solutions

• Ken Hoadley, Vice President of Engineering, Sensable Technologies

• Buzz Kross, Vice President of the Manufacturing Solutions Division, Autodesk, Inc.

• John McEleney, CEO, SolidWorks Corporation

The purpose of the session was to discuss how CAD software might be made more productive in the future. During the past 20 years, the computer-aided design (CAD) industry has simplified software user interfaces to enable engineers to design products more quickly and efficiently. But three-D CAD is still harder than it should be, often forcing engineers to spend more time thinking about how to use their software than exploring creative possibilities for new products. Is it possible to transform CAD/CAM technology from the complex set of tools it is today to a transparent extension of engineers' creative intents?

To focus the discussion, we asked the panelists each to comment on four questions. Here is a summary of their responses.

When creating three-D models, designers must not only think about their product, they also must struggle with their CAD software to discover which of a myriad of nuanced, yet similar functions they must use to get the desired product model. What can makers of CAD software do to simplify the number and complexity of functions designers must master to get their work done?

PLM Solutions’ Chuck Grindstaff said his company’s Unigraphics and I-DEAS development teams are employing a variety of tactics to make their products easier to use. First, developers are combining multiple related functions into more powerful, more general capabilities. For example, multiple functions for blending surfaces are being combined into fewer tools with options the user can set to achieve desired results. EDS also is developing more tools tailored to specific industrial process, such as stamping, forging, casting, and injection molding. Lastly, PLM Solutions is trying to make commands more consistent while reducing the number of mouse clicks and menus required to complete design tasks.

PTC’s Mike Campbell said his company is working to simplify Pro/ENGINEER. “We had 86 commands in Pro/ENGINEER that were used for creating and editing geometry and we consolidated them down to just 23 [in the most recent Wildfire release],” he told the audience.

Autodesk’s Buzz Kross said features used to design machinery should satisfy functional requirements, not just provide abstract geometric shapes. “We need to move it to that level in manufacturing where ribs are really ribs and behave like ribs. A boss should know it’s a boss.”

SolidWorks’ John McEleney believes reliability is an important factor in making systems easy to use. Engineers must be able to try different approaches to solving problems without fear that their systems will crash or that they won’t be able to undo an operation.

Ken Hoadley says his company’s CAD software simplifies design by employing a fundamentally different architecture from the leading CAD systems. Sensable’s FreeForm Modeling and Concept software products let users sculpt what appears on the computer screen to be digital clay using a proprietary “haptic” digitizer that gives force feedback. “Most people say ‘wow’ when they see it. It’s very natural, very intuitive,” Hoadley said.

Unless changes are planned well in advance, attempts to modify CAD models will produce error messages, broken features, and ultimately a failure to update the model. What improvements can developers make to their CAD software to increase the odds that changes can be made without rebuilding entire models?

Both EDS’ Chuck Grindstaff and Autodesk’s Kross said they believe that direct-face operations that are independent of feature definitions will enable designers to make changes more easily. With EDS’ Unigraphics version 18, for example, designers were given the ability to select faces and drag them to new positions without invalidating underlying feature relationships.

PTC’s Campbell says form features need to be more agile. “The idea is to elevate or abstract at a little bit higher level the definition of what you’re trying to do,” Campbell said. “Imagine creating a boss, putting some drafts on it, putting a fillet around its base. Later on you decide the boss shouldn’t be a circle, but should be a square instead. In many cases, that [type of change] will cause the drafts and the rounds to fail. The references have changed and the system doesn’t know what to do. What we have done is we’ve allowed you to elevate the definition of that boss and to say ‘I want a fillet or draft on the sides of this. I don’t care how many sides there are. I don’t care where they intersect the part. Just put a fillet and draft on there, and as the model changes, let the geometry update naturally.’ That being said, there are still going to be situations where the model fails, and I think that it’s important we provide you tools to quickly interrogate and troubleshoot exactly what has happened, where features have failed, why they have failed.”

Grindstaff of PLM Solutions also said his company has implemented what he called “selection intent” that makes models easier to change. Like Pro/ENGINEER customers, Unigraphics NX users can specify that all edges of an object be rounded regardless of the number of edges it has. Changing the number of edges or even changing a polygonal shape to a round one doesn’t invalidate the rounded features.

Grindstaff said PLM Solutions is working to remove the requirements for the user to think about the order in which features are evaluated. Parts and assemblies created with EDS’ Knowledge Fusion applications contain rules that describe how products of a certain class, such as an oil pan, connecting rod, or tool assembly are supposed to behave. This intelligence enables such product models to adapt to changes without feature failures.

SolidWorks’ McEleney thinks better training would help designers create models that enable changes to be made without causing feature failures. “It’s a rare user who can take [CAD] software out of the box and start to use it [without training]” McEleney said.

Ken Hoadley said feature failures are not a problem for his company’s CAD software because there are no boundary representations or features to fail. To make changes, the designer adds material to places where it is needed or carves away material where there is too much. Sensable’s Freeform Modeling Plus includes “proprietary technology for checking and correcting draft angles” that works on highly intricate geometry.