Fast & easy flow simulation runs inside 3-D CAD.

To help push mold-filling analysis to the forefront of the part- and tool-design process, AC Technology of Ithaca, N.Y., recently developed a new version of C-Mold that runs within 3-D CAD environments. This new program, called C-Mold Quick-Fill, features a streamlined input scheme and runs mold-filling simulations roughly 10 times faster than the full-blown C-Mold package. QuickFill also costs less.

"So far, the impact of CAE technology has remained mostly in the hands of a few analysis specialists," says Peter Medina, president of AC Technology North America. "QuickFill is designed to bridge the gap between the design world and the analytical world."

For now, QuickFill runs exclusively within the Pro/Engineer 3-D CAD package from Parametric Technology Corp. of Waltham, Mass. A second version of QuickFill will soon be available for 3-D CAD systems from EDS Unigraphics of Troy, Mich. AC Technology will offer the program to other CAD vendors as well.

EASIER TO GET STARTED

To make filling analysis more designer friendly," QuickFill drastically cuts the number of inputs needed to initiate a simulation. Once a 3-D model has been created and meshed in Pro/Engineer, the user just selects gate locations and types in two pieces of material information - the resin type and its melt-flow rate. In all, it takes about five mouse clicks to set up, launch, and view a typical filling analysis from the 3-D model. QuickFill outputs include those found in C-Mold proper: fill time, pressure, temperature, weld-line location, shear rate, and shear stress.

Underlying the input reductions are "intelligent" algorithms that automatically interpret information from AC Technology's materials and machinery databases. Standard C-Mold simulation software normally requires the user to enter a much greater quantity of viscosity information about a specific grade of material. But QuickFill users need only enter a generic material type and a simple melt-flow rate. The software makes things easy because its proprietary algorithms turn multi-point, non-linear shear/viscosity curves into simple melt-flow numbers for entire resin families.

QuickFill incorporates "injection-machine dynamics" defined in AC Technology's molding machine database. "The mold plus the injection machine is a system that doesn't have an infinite range [of capabilities]. QuickFill takes that into account," says Medina. For example, the software considers the expected limits on injection speed and pressure that a particular machine and mold would be capable of. Another set of algorithms transforms database information into suggested process values, such as for injection time. Thus, QuickFill automatically calculates process conditions that a C-Mold user would have to specify before the analysis could be run.

Because it runs within the CAD package, QuickFill allows users to evaluate part and mold designs immediately, not only to refine those designs but also to evaluate processability. "For example, the program can check the sensitivity of the process to variations in melt-flow index," explains Dr. V.W. Wang, president of AC Technology's worldwide operations.

SPEED AND ACCURACY

During a recent demonstration run on a Silicon Graphics "Indigo" workstation, QuickFill simulated the filling of a cellular phone housing (with a 1249-element mesh) in just 1.5 minutes - plus a few seconds more for the weld-line locator. Medina points out that a full C-Mold analysis of the same part could have taken at least five to 10 times as long. Much of the speed improvement springs from the input reductions, which have eliminated some of C-Mold's "overhead" - that is, input/output demands that can idle the CPU.

Despite the speed enhancement, QuickFill does not replace C-Mold. More complex tasks, such as cooling and warpage analyses, demand a full C-Mold simulation. What's more, the simplified inputs entail a sacrifice of accuracy, which could be significant to some users. As Wang explains, both QuickFill and C-Mold employ the same computer code to solve filling problems, but input simplification can change the accuracy level. C-Mold allows users to be far more specific about their material, injection molding machine, mold, and process conditions. Still, QuickFill typically gets to within 10-15% of C-Mold results, Wang says. "That's less variation than many molders see day-to-day on their shop floor."

If necessary, users can pass a QuickFill analysis over to C-Mold without re-entering the bulk of simulation information. For example, during a recent demonstration, an injection molded part simulated in QuickFill was later simulated as an injection-compression molded part in C-Mold (see New Products section).

LOWERING THE COST BARRIER

QuickFill's relatively low cost may remove another barrier to mold-filling analysis. The software will sell for under $10,000 - less than half the price of the full C-Mold package. Users would have to figure in the cost of Pro/Engineer as well, but Medina notes that most CAE users already run 3-D CAD.

Other more accessible CAE tools may also hit the market in coming months. Medina says QuickFill is the first of a planned series of "quick CAE tools," including ones for cooling analysis, gate location, runner design, weld-line quality, and vent design.