Surfaces, solids, and wireframes for faster mold design

Nowhere in the molding industry are production time constraints more keenly felt than in moldmaking. Speeding up the concept, design, and analysis phases of product development is a relatively simple task compared to compressing the time it takes to make a mold. In the past, using 3-D CAD to create complex cores and cavities was one answer to the problem. Unfortunately, mold designers often had trouble when the time came to translate those solids into the surfaces needed for NC machining.

Baystate Technologies' president Robert Bean believes the company's newest version of Cadkey 97 (release 2) can smooth the process from solid to surface to wireframe. The new software incorporates Acis 3.0 modeling kernel ("Surface definition improves at the core," November 1997 IMM, p. 79), which brings significant improvements in robustness, speed, and shelling for plastic part design.

During a recent interview, Bean explained why features of this newest version are attractive to moldmakers. "One of the major obstacles for moldmaking has been the ability to accurately translate various parametric CAD files. So we have improved IGES translations for surfaces and solids, conducting benchmarking tests with Catia files and others. Also, there are additional translators, such as the IGES translator available from FastSurf, so you're not stuck with one way to get geometry in and out."

With the new release, users can work on the model without worrying about the parametrics. There are some limitations--while mold designers can delete features or holes, refillet, or delete fillets, they can't change shell thickness. In the future, an add-on module will allow users to work with parametrics if they choose.

Rather than one specific tool, Cadkey 97 provides 2-D, 3-D solids, wireframe, and surfaces with FastSurf or FastSolid, as well as NC programming with FastNurbs (see sidebar story). "Real designers are often working in all of these areas, so we've created an approach to everyday design that says you can use any method interchangeably," notes Bean. "In the future we will be adding a deformable surfacing capability, which allows you to select a surface and stretch it."

Another benefit of the new version is that it includes Acis DLL, which allows users to keep one copy in memory and lets other programs share it. "You don't have to load another copy of Acis," Bean says. "Every time you load a solid-modelingbased product, you use up memory and slow down processing time. That doesn't happen with DLL."

Because tooling applications are a target market for Cadkey, Baystate conducted some extensive feedback sessions with current users and potential ones. Moldmakers who participated in the research indicated they were generally looking for easier editing techniques.

So the software now contains an easy way to define hot keys specifically for tasks such as mold design, modeling, or drafting. Other, more esoteric modeling features include tweaking, which allows designers to take a face on a solid and project or extrude up to another surface. Finally, users can get detail drawings from the solid model. Cross sections and side views are created automatically.

Across the board, Cadkey 97 R2 contains large performance increases. According to Bean, loading part files is now twice as fast as the previous version, and rendering is up to three times as fast. A 2-D file for a catamaran car ferry, for example, used to load in 40 seconds, and now loads in 5 seconds.