3-D CAD for Conceptual Design and Beyond

This article will look at the benefits of using 3-D CAD in relation to the entire process of product development as well as define the role it plays in the final production process.

For many companies, one of the most grueling stages in the development cycle was that of constructing prototypes required for geometric verification and capability testing. For example, automobile industry engineers typically used sand molds for components such as intake manifolds, exhaust manifolds and cylinder heads. Before CAD, producing the molds required to cast the first article was a long and complex process, which involved building wooden models and additional sand models. Many manufacturers have taken advantage of high-end CAD systems to compress their product development cycle and beat their competitors.

But rather than cover the traditional step-by-step processes - such as concept drawings and 2-D CAD - employed by many companies, this article will look at the benefits of using 3-D CAD in relation to the entire process of product development as well as define the role it plays in the final production process.

Feature and assembly level systems are playing greater roles in next generation software. The driving force behind this evolution is the increasing complexity of shapes and sizes in new products. Many companies have migrated to programs that are able to process complex components, illustrate geometric parts and their details, generate assembly drawings for company designers and have the ability to exchange feature-level data between CAD systems. Up until two years ago, software was a pretty generic animal. But all that has changed. With the market becoming saturated with CAD/CAM systems, systems peddlers are coming up with software that is specifically targeted at industry niches, like molds.

Industry-specific integrated software also has helped cut manufacturing leadtimes dramatically.

Using an assembly modeling process, Carlson Tool and Manufacturing, Inc. (Cedarburg, WI), a producer of automotive battery molds, was able to slash its lead production time down from 16 to just eight weeks through an integrated CAD system.

"By using assemblies we can put many more engineers on a project at the same time using the same geometry, so any changes that are made quickly ripple through the entire design," says Brad Wagner, engineering manager of Carlson's CAD/CAM system. "We can have more than one designer, we can have detailers, we can have the quality control department, the programmers as well as people on the shop floor all looking at the same geometry at the same time."

Wagner says the company's strategy was to share its work - which included holder blocks, lead inserts and cavities - across multiple programmers. Working together instead of apart lead to saved time, money and a better product.

Carlson designers and engineers also found that a 2-D part interpretation print is more of a reference point and that the 3-D model is really gospel, particularly when dealing with "swoopy" surfaces that are neither linear nor circular.

One California-based company recently developed a real-time, visual collaborative commerce software platform, which enables users to view, question and link to existing media from anywhere within a company. Multiple, simultaneous users can share visual information central to their design and review process: design, manufacturing, supply chain, sales, marketing and maintenance.

This system improves design quality and eliminates design errors by getting early feedback from reviewers, reducing product design cycle time and thereby shrinking the time it takes to get the product to the marketplace.

Another facet of the program is intelligent streaming technology that eliminates downloading and play delays. By not having to download video or model information the software ensures that the data is current and security and propriety information is maintained.

"All you need for this type of specialized software is a local area network, TCP/IP protocol and clients," says Doug Kyer, vice president of software services at Vuent (Sunnyvale, CA), developer of this real-time, visual collaborative commerce software platform.

"There are minimal requirements on the server side; this software platform is compatible with most browsers and Windows systems."

For other time-compressed companies considering certain software, the rule especially with CAD programs should be Caveat Emptor - buyer beware. A CAD system needs to import and export both solids and surfaces. Some surfaces can let you tweak the file to conform to the originating CAD product. This "flavoring" allows the user to import the file exactly as the designer built it - either through a direct translator or a neutral format like the Initial Graphics Exchange Format (IGES). Ease-of-use is a big factor in getting quick results. Measurement function is useful for detailed analysis of parts to better plan the machining processes as well as for gathering information necessary in preparing accurate price quotations and/or job proposals. Having a graphic user interface and machinist intuitive NC programming helps shorten the learning curve.

With that said, the most important thing companies should keep in mind when deciding on a software system is to make certain whoever they deal with offers reliable support services. Many software peddlers provide training to those in a company's management, who then go on and provide more specific training to their employees. These so-called "user courses" can last a day or stretch out to a week, depending on how much software change is involved. Most of these have help desks and technical support lines that provide on-site help if the problem cannot be solved over the telephone.

Another point to consider before purchasing software is the CAD viewer. Can it handle the true geometric surfaces of the model and not just representations of surfaces, such as the tiny triangles one would see in 3-D Stereolithograpy Tesselation Language (STL) files. If the company's CAD viewer can only make out small straight lines, which could be triangles, its software has to guess at what the exact geometry means, which offers great potential for error. Triangles can only approximate a curved surface so tolerance inaccuracies are inevitable. A viewer should not only be able to see the true surface geometry of a piece, but also the relationship to all of its elements. These geometric inaccuracies are usually caused by incompatible tolerance settings on two CAD systems trying to exchange a model.

"With these systems, you don't have to buy a Cadillac," Wagner says. "But always test a lot of systems, don't rely on what you're told because software always has bugs in it - and sometimes does a little less than what the salesman tells you."