The latest versions of computer-aided design (CAD) software show clearly how the benefits of new and enhanced features are making these programs virtually foolproof when it comes to product and mold development and materials specification. When engineers and technicians know how to run these programs, chances are they will create viable parts and molds efficiently and economically, further shrinking time-to-market cycles.

This is because software developers are loading their products with capabilities that produce a seamless flow of design, simulation, materials qualification, and production-cost estimates. Current programs achieve major gains in precision and speed—and in connectivity: Designers in most cases no longer worry about data transfer and translation issues when using these new versions.

As a result, product developers, processors, and mold designers have access to a powerful array of software they can use to broaden their capabilities and productivity and increase business opportunities. Following are representative samples of key advances that are taking place in CAD software development.

“Virtual Molding”

Sigma Plastic Services has upgraded the SigmaSoft product line with Virtual Molding, software that reproduces complex interactions between mold components and thermoplastics over multiple simulations of production cycles. Part behavior during molding is thus precisely demonstrated, eliminating the need to make assumptions about in-mold behavior, says Matt Proske, vice president of the company, based in Schaumberg, Illinois, USA.

The development of the software focused on increasing calculation speeds in these areas, Proske explains. The software becomes, in effect, an additional molding machine. “Process and tooling adjustments can be done with significant time and resource savings,” he says. “As reasons for part or production problems become evident, process understanding is achieved.”

Among the advantages this provides is early identification and repair of defects in part design, along with incomplete or unbalanced filling, core deflection, and other mold problems. Price quotations can, moreover, be refined with data from Virtual Molding software. Proske adds that molds optimized with the software have achieved “first-shot success, thus freeing resources on the shop floor for part production and strengthening the competitiveness of injection molders.” 

SigmaSoft developed mathematical models to describe the in-mold behavior of thermoplastics in a number of areas—warp, contraction, and residual stress, all of which can affect the mechanical properties of parts. The software also evaluates cavity temperature, the layout and geometry of tempering channels, the mold steel, thermal properties of the resin being molded, and shear-induced heat dissipation during filling.

Proske terms this a “holistic approach,” and says it allows Virtual Molding software to “accurately predict temperature at every point and time in the process inside and outside a mold.” This permits, among other benefits, optimization of mold design to reduce residual stress in parts.

The software also reproduces post-crystallization behavior in materials, which can induce part stress. For reinforced resins, it generates data on viscosity and its effect on fiber orientation, another factor in part performance.

Proske believes the software is accurate and versatile enough for use in designing tempering systems for injection molds. This would, among other benefits, assist in achieving cycle-time reductions.

Packed Packages

SolidWorks, a division of Dassault Systems, had been productizing and marketing CAD software developed by Simpoe, a French company specializing in injection molding simulation. The arrangement was so productive that last year Dassault, which is also based in France, acquired Simpoe. Peter Rucinski, senior product portfolio manager of SolidWorks in Waltham, Massachusetts, USA, says that as a result, his company gained access to all of Simpoe’s technology and thereby extended its simulation offerings.

The result is a revamped software lineup that reflects new capabilities in mold design and part analysis. SolidWorks now offers three main packages for plastics: Standard (which was called Professional before the Simpoe acquisition), Professional (formerly Premium), and Premium (which was Advanced). Standard software is dedicated to mold-filling simulation; Professional simulates filling, packing, and mold layouts (including analysis of runner systems); and Premium simulations include advanced cooling, warpage, and related functions.

All of these packages are fully embedded within the software. “If someone is designing parts or molds, there is no need to worry about interfaces, data translation, or association to CAD models,” he remarks. Designers can easily move from simulation to part and be sure all data are automatically saved and updated, and go to production when designs are finalized.

Additional features include a mold venting function, Nominal Wall Thickness Advisor that identifies part areas that could cause shrinkage and warpage, and a regularly updated database of 4,000 resins.

Rucinski says the need for simulation is stronger than ever as developers work to optimize part and mold design. The functions—new and upgraded—that SolidWorks has added are intended to give users all the capabilities they need to apply this technology accurately and competitively.

Speed, Compatibility, and Simplification

“The use of simulation is more intense,” agrees Thiery Marchal, global industry director at Ansys, which is based in Canonsburg, Pennsylvania, USA. He identifies three areas of most concern to the users he works with: speed, compatibility with new materials, and simplified user interfaces.

This last is especially important, since it permits users who aren’t familiar with computational fluid dynamics (CFD), a foundation of fluid-simulation software (as in resin flow), to work with programs effectively. Marchal says these interfaces represent the “democratization of simulation.” Ansys includes them on Polyflow structural and CFD software. “A designer or other non-CFD expert can work with the software without compromising the density and intensity of the simulation,” he notes. A complex model of a part or mold is hidden behind the interface, and displayed by keystroke when needed.

Polyflow software is also configured to perform rapid simulations to efficiently test multiple designs of prototypes under diverse end-use conditions. “Our new solvers are optimized to exploit the GPU (graphical processing unit) of any computer for maximum simulation speed,” Marchal says.

Recent capabilities of Polyflow include modeling anisotropic multilayer composites and calculating the non-linear strain-hardening behavior of blow-molded and thermoformed plastics. Strain-hardening is a counterintuitive behavior in some polymers in which the more they deform at temperatures lower than their recrystallization range, the more resistant they become to further deformation. Marchal says this makes them “particularly safe materials” for some applications.

A French company recently used Polyflow software to redesign a 1-m³ (264-gal) water tank, in the process racking up savings of $1.75 million, based on a $5/kg saving of polymer for each tank. The designers wanted to reduce the resin used in blow molding the tank without affecting its load resistance. Polyflow simulations and structural analysis allowed them to reduce material use by 10% and actually increase load resistance. The company molds 350,000 tanks annually.

There are dozens of CAD software developers and vendors worldwide. Those with advanced capabilities are pushing the technology into new and innovative applications, in the process making it available to more users and increasingly critical for effective part and mold design. Suppliers of market-leading software products that target plastics processing and mold-building include, for example, Autodesk (and its Moldflow subsidiary), Cimatron, Delcam, Exstream Engineering (part of MSC Software), Kubotek, Mastercam, and PTC.