New dimensions in mold analysis.

New Dimensions in Mold Analysis

The first generation of mold-analysis software made a lasting imprint on the way molds are designed. In less than a decade, computer systems for mold filling and cooling analysis have gone from being considered expensive, esoteric tools for a select few to a basic survival tool for the 1990's. Broad acceptance of mold analysis by injection molders and mold designers has spawned a whole new software industry. Taking advantage of advances in computer technology, suppliers are introducing new generations of software capable of modeling such additional variables as shrinkage, warpage and stress. (See PT, April '84, p. 74 and May '84, p. 75 for a survey of the earlier state of the art.)

In addition to a greater range of applications, systems have also grown faster, more accurate, easier to use, and less expensive. All this has made injection molding more productive, but there's more to come. Soon mold analysis software will be able to interface directly with your machine, leaving even less to chance.

Here's an update on how the technology has advanced in recent years, followed by a guide to suppliers of plastics mold-analysis software.

3D AND SOLIDS: BIG ADVANCES

Probably the biggest improvement that has occured throughout the industry has been a transition from two-dimensional (2D) "layflat" models to three-dimensional (3D) wireframe models and solids-based systems. 3D has brought about a range of new applications. With the early 2D systems, designers created drawings in basically the same manner as traditional draftsmen, saving little time over the manual process, except that modifications could be made faster on a computer screen. More important, 2D models utilized somewhat crude abstractions of actual part geometry, and they required the user to make assumptions about the very thing the programs were intended to analyze - plastic flow - and those assumptions influenced the results the computer would generate.

3D systems brought about greater dimensional accuracy, the ability to employ numerical control (NC) for mold machining, and higher levels of engineering analyses. But a bigger advantage is its ability to model 3D assemblies. The designer can select the coordinate system that best shows the detail to be illustrated. Modifications are made in that view and the system will automatically add the changes to all views. With a 3D system, you can zoom in on details, pan across the drawing, and even dynamically rotate the design for viewing from any perspective. Parts can be scaled, rotated, translated, and duplicated automatically.

Many designers consider 3D to be the best means to avoid wrong guesses about flow patterns, since the computer derives them without reference to starting assumptions by the user. Even though it may take longer to initially prepare a 3D finite-element description of a part geometry than a 2D layflat, 3D technology provides a more precise description of the part. It will ultimately permit the full integration of part design with processing analysis and manufacturing.

3D finite-element analysis software has brought big changes since the first 2D cooling analysis software was introduced. Initially, it was used primarily to optimize sizing and layout of cooling channels in the mold, and to determine flow rates, coolant temperature and cooling time. Nowadays, 3D cooling analysis can do all that, plus provide color-shaded "maps" of part surface temperature distribution at virtually any point in time.

Recently, solid-based systems have been introduced by suppliers such as Structural Dynamics Research Corp. (SDRC) and Matra Datavision (see PT, Jan. '89, p. 15). Designing in solids is different from designing in conventional 2D or 3D. Conventional design uses arcs, lines, and points. These are projected or joined until the model represents the design. Solids employ 3D "primitives," such as blocks, cylinders, cones, toroids, spheres, and prisms. The designer can "add" and "subtract" combinations of these shapes to construct a model.

While solid modeling requires the user to become adept at a different design methodology, there are advantages. Solid modeling systems provide an informationally complete database that permits calculations of mass properties such as area and volume, as well as sectioning, hidden-line removal, and color shading. Solid models bring a sense of realism to the design and manufacturing process that was previously attained only by building a prototype. Solid models can provide representations of assembly configurations, and automatic interference checking for movable cores and other mold functions. Solid models also improve communications between mold designer and builder through clear, unambiguous images that describe not only form, fit and function, but also weight, volume, and inertia properties, which can be utilized for cost and performance calculations.

Finally, solid models can provide geometry to perform complex three-to-five-axis, sculptured-surface NC programming for actual mold machining. Machining methods that don't directly use surface information from the solid model often result in molds that differ slightly from the original design intent, are not repeatable, and usually require greater lead time. Using NC to produce tools can significantly reduce these problems and can cut tool production cycles substantially. Moreover, lost production due to inaccurate tooling can be eliminated.

FASTER CHIPS AID ACCURACY

More powerful microprocessors have enabled suppliers to offer systems with greater speed and accuracy. For example, the last year or so has seen proliferation of systems that depict the flow front "dynamically," where all flow conditions are recalculated as each node in the mesh is filled. Such a calculation is said to be a more accurate method of calculating and depicting flow-front advancement than some earlier approaches that made limiting assumptions about the end point of mold filling and then interpolated the intermediate stages of fill. Instead, "dynamic" calculations start at the beginning of flow and calculates each next tiny increment of flow from the sum of those that have preceded it. (See PT, Jan. '85, p. 67 and April '88, p. 105 for discussion of different approaches.) This enables the user to see what is happening in the mold at any point in the filling cycle rather than at a predetermined, limited number of points that were offered with early systems. Such a calculation is very computer-intensive (since there are many more nodes to deal with in a finite-element mesh than there were "flow segments" in a traditional layflat) and wasn't practical with early systems because of the time it would consume.

In fact, even with early 3D systems, the size of the finite-element model that could be analyzed was very limited. For example, early mold-analysis software available from SDRC had a limit of 500 elements in a finite-element mesh. It initially took a DEC minicomputer 8 hr to complete the analysis. "Now the same analysis takes 20 min, and the potential size of the model is virtually unlimited," says Russell Stay, SDRC's product manager. He says most of SDRC's users try to limit the mesh to 2000 elements, "But we've seen users max go up to 6000 elements."

Speed was a big problem with early mold-analysis computer systems. Most systems were host-computer based - that is, users sat at satellite terminals with relatively little independent computing power, and their work was processed by a remote mainframe computer that was shared with many other users. This resulted in competition for a limited amount of computer power, and in substantial delays in completing the steps necessary to analyze a mold. While large host computers are still part of the scenario for many large companies, users are taking increasing advantage of the local computing power available through less expensive engineering workstations, such as those available from Sun Microsystems and Apollo Computer.

Because of their slowness, early systems made more assumptions about melt-flow patterns within the cavity than today's systems do. For example, most early systems assumed there was balanced heat flow, and that the hottest spot was in the center of the part. But that's not always true. Newer systems that can analyze unbalanced heat flow can also handle thermosets. With newer systems, the accuracy of the results is less dependent on the expertise of the user than previously.

Complaints from users have brought about systems that are more "user-friendly." SDRC and Unisys CAD/CAM, Inc. (UCCI) are among the suppliers who have totally revamped their user interface to make it easier to use. Early packages were developed by computer experts with little regard for the end user. Stuart Caren, product manager at UCCI, concedes that its system, as originally introduced, was "extremely accurate, but virtually unusable for even an above-average engineer."

NEW TYPES OF ANALYSIS

Perhaps of most importance to users are the new types of analysis programs that have recently become available. From a foundation built on filling and cooling analysis, new software has been developed to analyze heat exchange, deflections in the steel of the mold, stress in the molded part, and finally warpage and shrinkage of the plastic component. These modules generally use the same geometrical mold description developed for flow analysis and can also make use of the same results display routine. These newer applications exchange information interactively with flow analysis and with one another, as integrated analysis tools.

At the forefront of these new applications is the capability to predict part shrinkage. This software is helping many molders of close-tolerance precision parts, who need to know precise values of a number of part dimensions. The research necessary to develop this type of software has been time-consuming and difficult. A big complaint about early shrinkage analysis was their inability to accurately predict the variation in shrinkage rates across all dimensions of a specific part.

Mold designers have traditionally relied on resin suppliers for an average shrinkage coefficient, which they have attempted to extrapolate into multiple shrinkage compensation values for critical dimensions of a part. But success at this method has depended upon the skill of the designer in allowing for the effects of changes in wall thickness, angle of shrinkage relative to direction of flow, and other factors.

Most early research on shrinkage analysis was directed at studying mold shrinkage as a function of principal variables of the molding process, such as pressure, volume and temperature. But much more than these three variables need to be looked at. Ernest Bernhardt, president of Plastics & Computer Inc., says the true number of variables is closer to 30. "Mold shrinkage is the end result of a complex sequence of changes in pressures, temperatures, and other parameters throughout the filling, packing, and cooling phases of the cycle," he says. "Therefore, a key element of shrinkage analysis is time. We are not only interested in end-point conditions, but also in how we get there." (See PT, Jan. '86, p. 81 for discussion of Plastics & Computer's shrinkage analysis.)

Shrinkage evaluation should be part of a comprehensive molding analysis, taking into account the molding conditions selected through prior flow and cooling analysis. A shrinkage analysis package under development for nearly four years by Moldflow Pty. Ltd. and scheduled for commercial release sometime this year, is said to permit designers to predict actual shrinkage rates across all critical dimensions of a molded part. Says George Forbes, general manager of Moldflow Inc., "The key to shrinkage software is that it has to consider many factors and variables, which do not exist in isolation but interact in a complex manner." Among the principal factors considered are thermal contraction, differential crystallinity, orientation, and mechanical constraints. These considerations give rise to a series of master variables, which are dominant in influencing the shrinkage of the molded part. These variables include the resin's nominal volumetric shrinkage, injection temperature, maximum shear stress parallel and perpendicular to flow, and cooling rate.

Although systems differ, most shrinkage analysis systems use the component geometry and finite-element mesh already generated for flow and cooling analysis. The shrinkage program calculates the master variables from results available within flow and cooling analysis, and combines them to obtain a graphic display of distribution of linear shrinkage throughout the component. Shrinkage can be displayed in a direction parallel or perpendicular to the direction of flow during cavity filling. Also, the magnitude of the shrinkage can be given.

STRESS/WARP ANALYSIS ARRIVES

Distortion and warpage of a part is a result of stresses caused by differential shrinkage. Therefore, to predict warpage, an analysis of shrinkage must first be completed. Shrinkage data are then converted to nodal force data inside the warpage analysis program, which is analogous to a large-displacement stress analysis. The warpage analysis program also uses the existing geometries from flow analysis and takes data on mechanical properties of the resin from the resin database. Using this information, the program produces predictions for the distortion of the model, and information on the molded-in stress distribution in the part, which will have a bearing on part life and performance and, therefore, on quality.

In Moldflow's new software (PT, April '88, p. 103), warpage analysis can be conducted for unrestrained shrinkage and also for cases where mechanical constraints - such as mold cores or inserts - will interfere with shrinkage. Moldflow's warpage analysis results can be displayed, once again, using the same integrated display results program.

WHAT'S AHEAD

A link from mold design to machine setup is the most significant development that will occur in mold analysis software in the near future. Thus far, only Plastics & Computer Inc., along with the injection molding machine suppliers Netstal, Sumitomo, and Sandretto, has demonstrated such a capability, which depends upon a software interface that translates an optimized mold design and associated set of processing conditions directly into electronic setup instructions to a controller on a particular brand and size of injection machine. Although no customers are yet using this approach to automatically set up machine controls, several are manually transferring the calculated settings to their molding machines, and have used this approach with at least a score of molds (PT, Jan. '87, p. 55 and Jan. '88, p. 13).

The first step in Plastics & Computer's automatic machine setup is a thorough moldability analysis. The first step is to specify a level of part quality (tolerances) desired, number of cavities, machine size required, and a first approximation of cycle time with the company's MCO (Molding & Cost Optimization) analysis. (The software compares the machine capabilities to the requirements of the mold, and will flag any mismatch, such as a shot capacity too big for the part to be molded. The next step is to perform flow, packing, and cooling analysis on the total system of cavities, sprue, runners, and injection nozzle, using other programs in the TMConcept package. Those analyses permit optimizing the mold and predicting cycle time in the context of specified molding conditions, such as melt and mold temperatures, injection pressures, and injection rates. From data on a specific machine and its controller - supplied by its manufacturer - and the various mold analyses, the software generates about 350 setpoints for that machine and control, including temperatures for barrel, nozzle, adapter, and mold, plus all speeds, pressures and times. Settings for all steps of an injection speed/pressure profile can be determined, as well as multiple steps of screw speed and backpressure, and calculation of the point of switchover from speed to pressure control during injection. This is all done in an interactive mode that allows the user to confirm or refine the calculated values. Finally, the system runs a program to convert the data into a format understandable by the machine's controller.

Bernhardt from Plastics & Computer says that it's possible to adapt this approach to any type of machine, providing the user is willing to develop a database on his machine's performance. While this could be used to generate values for machine settings, it couldn't directly upload those values to the machine controller. That would require "translator" software, which would likely be developed by Plastics & Computer together with the supplier of the machine controls.

Who's Who in Mold-Analysis Software

The following are independent sources of mold-analysis software, or CAD/CAM suppliers that have developed their own proprietary mold-analysis systems. In addition to those listed, several other CAD/CAM suppliers offer flow analysis as "third-party" software licensed from the developer. Some of these CAD/CAM suppliers have done considerable work on their own to integrate third-party mold analysis with their own CAD programs, and may even have enhanced the mold-analysis software on their own.

MOLDFLOW, INC.

Trumbull, Conn.

More CAD/CAM vendors offer pre-and post-processors from their system to Moldflow than any other mold flow analysis system. The Moldflow system is a series of software modules that analyze flow, cooling, shrinkage, warpage and stress in an injection molded part. These analyses cover the fill, hold and cooling stages so that conditions within the mold are monitored until the part is ejected. Each module uses a common geometric database and generates the necessary input data for the next module in the analysis sequence. This approach minimizes the time required to perform the analysis, as the time-consuming data-entry step is reduced significantly. Errors caused by inaccurate data entry are also minimized.

The Moldflow filling analysis program uses 3D finite-element methods to depict the flow path from the gate to the last point to be filled. Company officials state that substantially increased accuracy is provided by new "node-hopping" software that determines the flow front position at any instant during injection. With Version 5.2 of the software, calculation of flow-front position proceeds from the nodes contained in the previously calculated front position to the next group of nodes directly connected the latter. This provides so-called "dynamic" flow analysis, since a finite-element analysis is completed each time an addition is made to the front.

A 3D view of the cavity depicts weld lines, meld lines, and overpack areas. The program also determines mold and melt temperatures, first-stage injection time, injection pressure, cycle time, and clamp tonnage utilized.

Moldtemp is a thermal analysis package which helps optimize the cooling circuit (PT, Dec. '85, p. 16). The program calculates water flow and heat-transfer capability for each section of the cooling channel, temperature distribution profiles at the metal-to-plastic interface, pressure drop in the cooling circuit, and coolant temperature rise. Thermally conductive inserts and external heat sources can be included in the analysis. Moldtemp allows the engineer to vary the cooling-circuit geometry and flow rate, incorporate inserts and other variables, and graphically view temperature distribution over time.

The shrinkage module takes the results from the flow and cooling analysis modules and calculates temperature, rate of cooling, shear stress, direction of flow, and shrinkage both parallel and perpendicular to flow for a series of individual layers through the thickness of the part at each finite element of the model. The analysis extends into both the packing and cooling phases of the processing cycle. This allows the holding pressure and time for minimum shrinkage to be determined and the parameters controlling shrinkage to be monitored throughout.

Within the shrinkage module, there is also the ability to account for effects of asymmetric cooling on the part. If one side of the part is cooled at a different rate than the other, it will shrink to a different degree. This difference will introduce a bending stress, which can lead to distortion. This effect is superimposed onto the in-plane shrinkages and can be used in the warpage analysis to show the distortion caused by asymmetric cooling.

The warpage analysis module takes the local orthotropic shrinkage values generated in shrinkage analysis and combines them with the mechanical constraints on the part, such as gates, to determine the net distorted shape. Processing-induced stress values for each section of the part are also generated.

The stress analysis interface module accepts the part geometry from the common database, shrinkage factors from shrinkage analysis and external loads that the part is expected to experience in use. The stress analysis interface module generates a formatted input file for several popular finite-element analysis programs. The results are a complete structural analysis incorporating both external and residual loads.

The Moldflow systems reportedly run on a wider variety of computers than any other mold-analysis software. These include: various IBM personal computers; workstations from Apollo, Sun, Intergraph, DEC, Control Data, and Silicon Graphics; and larger computers from Hewlett-Packard, DEC, Prime, IBM, Control Data, Cray, and Convex. (CIRCLE 64)

PLASTICS & COMPUTER INC.

Montclair, N.J.

Over the past 10 years, the TMconcept Expert System for Molding has evolved into an integrated system with capabilities for material selection, determination of molding conditions, flow analysis, cooling analysis, shrinkage analysis, part tolerances, and cost optimization. The latest release automatically determines optimum injection-rate profile (PT, Nov. '88, p. 91). The new capabilities are incorporated in the faBest program for finite-element flow analysis. Users set an upper limit to injection pressure and the new software automatically adjusts the flow rate profile to adhere to the designated pressure limit. This means that injection rate can be programmed within the pressure or clamp force capacity of a given machine.

Officials at Plastics & Computer believe that its finite-element model for flow analysis, called faBest, is unique in its ease of use and the reliability of the solutions, owing to its application of quadrilateral elements with eight nodes and one centroid. Most systems employ triangular finite elements. Plastics & Computer believes that its use of quadrilateral elements provide better results in less time.

The company also offers a sophisticated group of shrinkage programs for different levels of precision (and requiring different amounts of computer time to calculate). Although they're generally intended to be used together with other TMConcept mold-analysis modules, at least one shrinkage program can be used on a stand-alone basis.

Plastics & Computer's ultimate objective is to offer an "expert system for molding," in which the computer not only "thinks or helps the molder to think," but also calculates and provides precise numerical information. This is one goal of the CAD-to-machine interface currently under development (see above). Such a system was demonstrated at the JP `88 exhibition in Osaka last November, on a Sumitomo machine molding an optical disk case. A fully dynamic flow analysis, using profiled injection, was performed using the faBest finite-element program. Cycle time for this part was reduced by 50% through the use of valve gating and very high injection pressure and speed. The TMconcept software guided the user to this solution and defined the need for a high-quality molding machine capable of a precisely reproducible injection rate and the holding-phase profile.

Plastics & Computer is in the process of developing software aimed at process fault analysis at the shop-floor level. Since the machine can be set automatically at the completion of a TMconcept analysis with the current software, all mold/part characteristics and their interrelation with the process are "memorized" in the molding machine's process control system. Plastics & Computer's new software for fault analysis will make full use of this large amount of information to help the operator through "trend indications" to prevent or correct problems caused by variations in material or machinery performance.

The TMconcept runs on computers based on Intel's 80286 or 80386 microprocessors. (CIRCLE 65)

UNISYS CAD/CAM INC.

Boulder, Colo.

UCCI (formerly Graftek) introduced its first mold-analysis software in 1982. Sold as OptiMold, it included 3D CAD and NC CAM software, graphics mold-design software and two analysis products - Simuflow and Simucool. The latter were originally 2D filling and cooling analysis products based on research done by the Cornell Injection Molding Program. Although said to be extremely accurate, they were still only 2D analysis programs and the results were either tabular data or graphs.

In late 1985, UCCI introduced a 3D finite-element mold-filling analysis program, called Simuflow3D, based on the latest Cornell research. The initial release of Simuflow3D had an enhanced viscosity module for even better accuracy. The user could now select gate locations and see the melt-front advancement, along with pressure and temperature distribution, as "contour lines" on the 3D wire-frame model.

In the last few years, UCCI has enhanced the user interface and proceeded with additional developments. New enhancements include analysis of the packing phase, display of shear stress and shear rates, velocity vectors, packed and unpacked elements, and analysis of variable fill rates. The plastic viscosity model has been further enhanced to extend the range of processing conditions. Two major user objections were corrected: the limited size of the model that could be analyzed and the time to complete an analysis. With the latest release, any size model can be analyzed and the program runs faster without any loss in accuracy.

The greatest difficulty in finite-element analysis is creation of the model. Since Simulflow3D is integrated with UCCI's geometric modeling software and finite-element modeler, both products were simultaneously enhanced so the designer or engineer could more easily create the models (see PT, Jan. '89, p. 17).

Display capabilities have also been improved. In addition to more data being saved for display, the number of lines can be set by the user for varying amounts of detail. Now, the distance between adjacent isobars or isotherms can be as large or as small as the user desires. (In early releases the system would automatically draw only nine isobars.) The same is true of shear stress and shear rate or melt-front contours. Ability to display 3D shaded color images, rather than just wireframes, is a recent addition (PT, June '88, p. 161).

Simuflow has also been enhanced to include more accurate viscosity models, branching segments, hot-runner systems, and more segments and flow paths. An automatic interface from Simuflow3D has been added to create equivalent segments for use in runner balancing.

While a major effort was going on to improve Simuflow, a parallel effort was aimed at improving Simucool. Early enhancements allowed the user to calculate cycle times, determine effects of changes in coolant, mold or plastic material, coolant flow rate and part thickness. Calculations have been added to determine if the coolant flow is laminar or turbulent and to calculate temperature rise and coolant flow rate in multiple cooling circuits.

The most recent development (PT, Jan. '89, p. 17) is Simulcool3D, a finite-element cooling analysis that uses some of the same files and programs used for Simuflow3D. With this program, the mold designer can model the mold, cooling lines, and part geometry with a finite-element mesh, assign coolant temperatures and melt temperatures, and see the temperature of the mold and plastic change as the melt cools. Hot and cold areas are visible, and mold cooling can be modified before the mold is cut. This enhancement was developed to answer customer demands. UCCI believes it is the only supplier to provide this type of software with a friendly user interface.

UCCI software runs on hardware from Unisys, Apollo Computer, and Hewlett-Packard. (CIRCLE 66)

CAE SERVICES, INC.

Bloomingdale, Ill.

This company was spun off from AEC, Inc. in 1988 in a management buyout. It retains the rights to all of AEC's mold-analysis software, which includes Moldfill II, Moldcool II, Moldheat (for thermosets), and Blowcool (for blow molding). Moldfill II was recently updated with additional capabilities, including animated material flow, a central modeling interface, and an expanded plastic material database. A new product is a runner-balancing program. This is a refined version of Moldfill, said to allow the user to size and balance runner systems quickly and easily. No graphics are required and it runs on an IBM PC-AT or compatible computer.

Moldcool software has been updated with a shaded-image post-processor that shows hot and cold spots on the part surface and allows the user to move and/or add cooling channels to balance the heat transfer. Cooling-channel design now includes straight round channels, baffles, bubblers, heat pipes, and helical channels. These new cooling-channel types are said to provide more accurate cooling design simulation.

Another new feature is the circuiting analysis program. It provides the user with the proper hose connection arrangement by calculating the heat load and resistance to coolant flow per cooling channel, and then determines how the channels should be connected together.

Software from CAE Serices runs on the IBM PC-AT and compatibles. (CIRCLE 67)

STRUCTURAL DYNAMICS RESEARCH

CORP., Milford, Ohio 

SDRC, in a joint venture with GE, began offering software for mold analysis in the early 1980's. It has since withdrawn its original 2D offering and introduced a new version last year, which was developed along with a consortium of users, including IBM, Eaton Corp., GE, and NCR.

Says SDRC product manager Russell Stay, "We found that large companies such as these are more concerned about accuracy than speed. So that's the focus of our software." Data can be shown for up to 20 different layer "slices" through the thickness of the part. "Most packages use eight or 10," says Stay. "We give up some speed, but it increases accuracy. We can show the results at any layer, for example, with cooling, you'd probably want the center because it usually cools last."

Unlike most other packages, which use only finite-difference, boundary-element, and finite-element analysis. The software couples part design with process simulation in a three-module suite of software: Mold Filling, Mold Cooling, and the Materials Data System. All form integrated parts of SDRC's new I-DEAS For Plastics software package (PT, Jan. '89, p. 15).

After completing initial part design and structural analysis using I-DEAS standard MCAE software, the first module of I-DEAS For Plastics is used to perform mold-filling analysis. The program uses 3D part geometry, a materials database, and process parameters to determine optimum runner design and further define process parameters for efficient filling. A finite-element description of the part and runner systems can be extracted from the solid using I-DEAS Finite Element Modeling, which can then be used to obtain desired flow pattern, temperature, and pressure results. Colorshaded "maps" of various flow variables through the part can be displayed.

Cooling analysis can then be performed using I-DEAS Mold Cooling. The cooling channel layout is described and can be graphically displayed using I-DEAS Solid Modeling for verificaton. The cooling process can be simulated as a function of time, with consideration of the heat transferred from the part through the mold to the cooling fluid and to the air. A 3D analysis can be used for complex parts and cooling systems, and colorshaded maps can be displayed. A part's tendency to warp during cooling can be analyzed via a "warp index," and warp deformation can be quantified using I-DEAS Model Solution. Qualitative shrinkage dimensions are also provided. Thermal stress results can be analyzed to predict potential failures.

Materials information is stored and accessed via the Materials Data Systems, built upon the I-DEAS Project Manager - a database-management system that can be tailored to track the properties of the material being used.

I-DEAS For Plastics runs on DEC computers, IBM mainframes, the IBM RT, and workstations from Apollo and Hewlett-Packard. Compatibility with Sun workstations is due later this year. (CIRCLE 68)

ADVANCED CAE TECHNOLOGY, INC.

Ithaca, N.Y.

AC Tech has developed flow and cooling-analysis software based on the Cornell University Injection Molding Program, independent of Unisys' developments from the same Cornell research. The company offers a group of programs under the name C Mold (see Aug. '86, p. 23 and Aug. '88, p. 13). These include C Flow, C Cool and C Pack, all of which are finite-element analyses based on 3D geometry, although the "local" analysis of flow in each finite element is on a 2D basis (the rationale is that most plastic parts tend to have relatively thin walls). Also included is C Flow Opt., a 2D version that runs faster and therefore can be used for convenient screening of a range of processing conditions to determine the optimum set. C Mold includes its own finite-element mesh generator, though others can also be used.

C Pack is the newest part of the package (see PT, Aug. '88, p. 13). This program uses the results of C Flow to extend the analysis beyond mold fill into the packing and holding phases. It can display a "contour map" of volumetric shrinkage, density, pressure, and temperature throughout the cavity at any point in time. Data can also be shown through the thickness of the part. Frozen-in stresses are also displayed, in order to help predict warpage and part performance in use.

Also new is a "materials selection" database of several thousand grades from U.S. and European suppliers. Each entry indicates whether it is among the 600 or so materials for which sufficient rheological data are contained in the C Mold database to permit flow analysis.

C Mold software runs on a range of hardware, from 80386-based personal computers to mainframes. (CIRCLE 69)

CISIGRAPH CORP.

Farmington Hills, Mich.

Cisigraph is a French CAD/CAM company, which initiated sales in the U.S. in 1988 (PT, June '88, p. 17). It developed its own flow and cooling-analysis software to go with its Strim 100 CAD/CAM package. Procop mold-analysis software offers both 2D "layflat" and 3D finite-element analyses, using a database of over 400 different materials. The package includes its own finite-element meshing module, but it can also accept a mesh generated by most other commercial packages.

Procop offers "dynamic" flow front analysis, where all flow conditions are recalculated as each node in the mesh is filled. Results can be displayed as either alphanumeric tables or as shaded images with regions in various colors showing the flow fronts and distribution of pressure, temperature, shear rate, shear stress, and percent solidification through the part thickness at any point in time. Any number of increments of flow - up to the number of nodes in the mesh - can be viewed. Data can be shown for five different layer "slices" through the thickness of the part.

The software also has the capability to analyze mechanical stress in parts as a result of molding conditions, can automatically balance runners, simulate hot-runner injection, calculate required clamp tonnage, select a filling method that optimizes time and temperature, and calculate the correct size of the mold-cooling system. Full cooling analysis is currently available in the 2D model; 3D capability is in development.

Cisigraph has developed software interfaces for transferring full geometric and surface data between other CAD/CAM systems, including those from Prime Computer's Computervision Div., CADAM, Inc., and IBM's CATIA. These go well beyond the currently limited capabilities provided by the IGES standard for CAD communications.

Cisigraph's software runs on DEC VAX computers and, workstations from Silicon Graphics. (CIRCLE 70)

ICAM TECHNOLOGY

Pointe Claire, Quebec

ICAM offers the Cadmould package of 3D and 2D flow analysis, 3D shrinkage and stress analysis, and 2D cooling analysis (intended for laying out cooling channels), which was developed by the IKV (Plastics Processing Institute) in Aachen, W. Germany. At present, the firm markets only in Canada. Flow analysis can display color isobars on a wireframe model; color-shaded image capability is in development. Also available are a materials selector program, which is said to help find a material that will fill the mold most easily, and special runner and gate design software developed by the National Research Council of Canada (see PT, Aug. '86, p. 21). 3D software runs on DEC VAX minicomputers, while 2D versions run on personal computers. (CIRCLE 71)

TECHANALYSIS, INC.

Indianapolis

This engineering and software consulting firm, specializing in fluid dynamics and heat transfer, started development a year ago of software for injection, compression and extrusion flow analysis (PT, Oct. '88, p. 14). 3D finite-element injection mold-analysis software is scheduled for commercial release this August. It reportedly includes stress and warpage analysis and accounts for fiber orientation in reinforced compounds. The company plans to be able to customize the product for individual users. (CIRCLE 72)

PHOTO : I/Flow software from Intergraph automatically provides graphic display of results from Moldflow analysis on Intergraph's CAD/CAM systems. Users can display time, temperature, or pressure data.

PHOTO : Plastics & Computer Inc.'s faBest program produced this output of isochrones/isobars for a polycarbonate optical disk cover. Note the weld lines about to form at the bottom of the picture.

PHOTO : Exploded view of car cassette player designed with Matra Datavision's Euclid-IS system and its Mold Technology package, which includes an interface to Moldflow.

PHOTO : Plastics & Computer Inc.'s TMconcept software shows the influence of holding time on shrinkage. With a valve gate, a short holding time can be used (A). The packing condition corresponds to a longer time (B), thanks to the melt compressibility.

PHOTO : A new feature of C.A.E. Services Moldcool II program is a shaded post-processor, which shows the hot and cold spots on the part surface and allows the user to move and/or add cooling channels to balance the heat transfer, which provides improved part quality and minimum cycle times.

PHOTO : 3D solid models provide greater clarity of visualization of complex shapes for mold analysis. (Photo: Cisigraph)

PHOTO : Procop software from Cisigraph (above) analyzes the molding process "dynamically," continually recalculating variables such as pressure, temperature, and shear rate for each minute increment of flow. With Cisigraph's Strim 100 CAD software, 3D shaded images can be produced, using multiple light sources, material effects, and shadowing to produce life-like effects.

PHOTO : Mold for a washing-machine rotor, developed with GE Calma's Plastic productivity Solutions, which offers interfaces to such "third-party" software as Moldflow and C-Flow from AC Tech.

PHOTO : Mold of a valve housing, as depicted by Unisys CAD/CAM Inc.'s Simuflow3D, which shows melt-front advancement, pressure and temperature contours, and pressure and temperature at each point as the part fills.

PHOTO : SDRC's I-DEAS for Plastics includes its own brand of 3D mold analysis. Shown here: a contour plot of mold filling times to guide the designer in selecting gate locations for optimal parts quality.

PHOTO : A new approach to predicting warpage is the development of CAE software modules such as Moldflow's SWIS package, which analyze the molding and cooling process to predict shrinkage at each area of the part prior to the prototype phase.

PHOTO : New from Unisys CAD/CAM, Inc. is Simucool3D, 3D finite-element mold-cooling analysis software. This software aids mold designers in determining the best location for cooling lines to achieve uniform cooling, which minimizes cooling time and warpage. Illustrated is the temperature across a 2D section of the mold after the part is filled.