Engineering Productivity Kit - CAD/CAM/CAE

DN Staff

June 23, 1997

16 Min Read
Engineering Productivity Kit - CAD/CAM/CAE

Software promises perfect plastic parts upfront

Newton, MA--Plastic has revolutionized manufacturing, forming parts of consistent quality, size, shape, and color in one operation and at low cost. As a result, the material has become increasingly popular in many industries--automotive, computer, and consumer.

But producing injection-molded parts often involves a complex operation. Many times plastic parts are not analyzed before production because of the time and expertise needed for simulation. The result: frequent and costly part redesigns and mold rework.

"Eighty-five percent of the part designs we receive require design changes to support the manufacturing process," says Bob Petit, design and analysis manager at manufacturer Nypro Inc. (Clinton, MA). "For a $300 million company like ours, verifying part designs up-front would save us about $200,000 per year."

Moldflow Corp. (Lexington, MA) hopes to make that a reality by enabling what it calls "process-wide plastics simulation." The company aims to bridge the gaps between part design, mold design, and part production through its Plastics Adviser Series software products.

First in the series, Part Adviser enables the part designer to quickly evaluate a plastic injection-molded part for "manufacturability." The software simulates plastics flow and gives practical advice on corrective actions for identified problems. For example, the software tells the user whether a part will fill properly, the location of weld lines, and whether and where air traps will appear. It also provides feedback on how modifications to wall thickness, gate locations, and material selection will affect the part's manufacture.

"Today, analysis is done too late, after the part is designed. At that stage, analysis requires 40 to 60 hours of an expert's time, and a fix, which is needed in most cases, is too expensive," says Lee Malouff, director of engineering services at Black and Decker (Shelton, CT).

Working directly from 3-D solid models generated in CAD, Part Adviser eliminates the need for data translation, meshing, mid-planing of models, and manual model cleanup. With no previous analysis or plastics expertise, designers can obtain accurate results in minutes rather than days or weeks, says Moldflow.

A special "Confidence of Fill" test helps users determine whether a part will fill, without having to interpret filling pattern and distribution results. A non-Newtonian, non-isothermal solver (patent pending) simulates shear heating, temperature and pressure distribution, and frozen-layer information behind the scenes.

In the confidence simulation, areas of the part model appearing in green indicate a high confidence rating, yellow notes a medium confidence level, and red shows areas with a low confidence rating. Sections showing red or orange may require design or material changes for the part to fill.

"Companies can now benefit from practical plastics manufacturing expertise early in the design process, and avoid costly modifications later on in manufacturing," says Ken Welch, VP of marketing at Moldflow.

Online advisors provide information on plastics manufacturing constraints and how plastic flow behavior affects part quality. Part Adviser is integrated with several CAD systems, including SolidWorks and Pro/ENGINEER. A stand-alone version runs with any CAD package that can generate an STL file.

Additional details...Contact Moldflow at (617) 674-0085, visit

Staff Editor Anna Allen contributed to this Productivity Kit.

News Flash

Make Web technology work for you

Cambridge, MA-based market research firm Daratech Inc. will sponsor a conference to show how Web technology creates a competitive advantage for manufacturers in the process and power industries.

Taking place July 28-30, 1997 in Los Angeles, Intranet/Web Strategies for Engineering and Manufacturing '97 will explore how Web technologies create highly reliable and expandable in-house networks for collecting and distributing graphics, text, voice, and video data for structured and unstructured engineering, manufacturing and plant design, and maintenance and operations.

For more detailed information and the conference agenda, contact Daratech at ph: (617) 354-2339, fax: (617) 354-7822, e-mail: [email protected], visit on the Internet.

PDM implementation takes off

The Kalthoff International (Cincinnati, OH) buying index reveals that an increasing number of companies are in the later stages of evaluating purchasing initiatives for product data management (PDM) and engineering document management systems (EDMS).

Study results showed 47% of discrete and process manufacturers--423 of 904--have active purchasing initiatives underway. Of these, two-thirds indicated they are in the final stages of buying a system--evaluating vendors, implementing a pilot or full system,or upgrading a current system.

For additional information on the index, contact Blaine Clark at (513) 794-3367, e-mail [email protected], visit on the Internet.

Simulation perfects life-saving helicopter seat belt

Phoenix, AZ--Traditional helicopter restraint harnesses, designed to maximize a helicopter pilot or crew member's safety, often prove restrictive. Pilots and crew members frequently loosen the restraint systems to gain comfort and mobility, but a loosened restraint system compromises safety.

To address the problem, the U.S. Department of Defense awarded Advanced Structures Technology, Inc. (AST) a contract to design a helicopter crew member pretensioning device (PTD). The PTD enables pilots and their crew to wear restraint systems comfortably until a crash onset, when the restraint automatically tightens around the occupant to reduce injury or improve the chance of surviving a crash.

According to AST, two-thirds of helicopter crash-related injuries and deaths result from upper torso flailing, leading to striking or being struck by objects or structures in the cockpit. To design the pretensioning device, AST needed to know how a body moves through space during a crash. AST engineers accomplished this using Working Model(r) dynamic analysis software from Working Model Inc. (San Mateo, CA) to define the body displacement (flail) envelope likely to be traversed by a helicopter crew member's body during a crash. For this, the design team used Working Model 2D to analyze the human, seat and floor structure, and the restraint harness.

"One of our engineers went through the Working Model tutorial and was up-and-running in one or two days," says James McLellan, AST lead engineer. "What's more, Working Model paid for itself on the first use."

AST calculated flail envelopes for three harness conditions, all with the occupant in the same initial position. The first condition had the harness snug on the occupant to simulate a properly tightened harness or a pretensioned loose harness. The second condition applied a 200-lb preload to the shoulder harness, simulating a pretensioning event on a snug harness. The third condition analyzed had four inches of slack in the harness. In all cases, the flail envelopes of the occupant's head, hands, and feet were tracked for comparisons.

"Mathematically, without Working Model it would have been a nightmare to create the clear picture we needed to develop the PTD," says McLellan.

The AST engineers conducted dynamic simulations using a 50-percentile male patterned after the GM Hybrid III crash test dummy, a 5-ft, 8-inch-tall, 163-lb person. A 5 lb helmet was added for the human model to represent a military flight crew member.

AST obtained the seat geometry by measuring an armored Navy helicopter seat. Next, engineers modeled the floor structure as a horizontal projection of the floor under the seat. This approach offered the largest foot flail envelope.

To obtain the largest head and hand flail envelope, AST did not model the panel, windshield, and ceiling. Instead, it modeled the seat and floor structure as a single unit with slide constraints to enforce motion only in the crash direction.

The resulting model uses a five-point restraint harness that includes shoulder harnesses, seat belts, and a crotch strap. McLellan modeled the shoulder harness as a rope with a spring attaching it to the seat back. For each condition, the spring rate on the short spring connecting the rope to the seat back was adjusted to represent the total spring rate of the shoulder harness.

The Working Model analysis and simulation gave AST engineers a clear understanding of how an occupant moves through space in the cockpit during a crash. This led to the design of a PTD that retracts four inches of shoulder harness slack in less than 35 milliseconds after crash onset, then locks the strap, significantly reducing the occupant's flail envelope.


Software automates the mold design process

by Peter Brooks, VP of Mechanical Engineering Products Bentley Systems Inc. Exton, PA

In the past, experienced machinists with many years of accumulated knowledge made mold bases. Now, Bentley's MoldDesignTM software takes the "black art" out of the mold design process. The software generates mold designs straight from 3-D solid-model parts, automating the process of designing plastic and high-pressure aluminum injection molds, freeing designers from creating mold plates and components, and detailing holes and slots.

MoldDesign uses rules-based technology and parametric libraries to generate fully detailed 3-D solid models of the mold from the original part. The streamlined workflow and information exchange improve productivity and part quality, and reduce time to market.

Users choose components, such as plates, leader pins, bushings, and ejectors, from several industry-standard catalogs inside MoldDesign. The software then uses these components to generate the injection mold. The software also provides "push-button" tools for the design of the mold-cooling system and generates a complete bill of materials, including plates,

inserts, component information, dimensions, and catalog numbers.

Because MoldDesign is part of the MechanicalSpaceTM user environment, project teams can perform modeling, detailing, structural analysis, kinematics, and manufacturing with a single engineering model.

Additional (800) BENTLEY; e-mail: [email protected]; visit

Software takes CAD to new speeds

A substantial increase in overall program performance and numerous time-saving enhancements highlight Autodesk's newest release--AutoCAD R14. The company says the new software is faster than both R13 for Windows and R12 for DOS.

The package boasts an improved graphics pipeline that uses less memory in loading files, and several productivity tools designed to save time. Among them: AutoSnapTM, which helps locate commonly used geometry during drafting, and tools for managing layers. Native raster imaging makes it easier to reuse paper drawings as a basis for drafting.

Solid fills, photo-realistic rendering, display ordering, and enhanced support for TrueType text creation and display improve presentation-quality drawings.

Several new features make communication and sharing designs easier. For instance, R14 includes reference file capabilities such as polygonal clipping and layer filtering. The ability to publish and access designs over the Web also is integrated into R14, along with single-click access to the AutoCAD support page on the Web.

Customization has improved through the use of ActiveX automation, which provides access to AutoCAD's core object and method set via Visual Basic. Meanwhile, features such as a network installation wizard, network license manager, multiple user profiles, and batch plotting ease the setup of R14 on a CAD network.

For more information call (415) 507-5000, visit

3-D interface speeds Rolls-Royce designs

Bath, England--The Rolls-Royce Industrial Power Group (IPG) wants to move analysis earlier into the design process to reduce time-to-market. Allowing engineers to quickly check stress values during product development would eliminate analysis backups and cut turnaround time. To achieve this goal, IPG asked ANSYS (Canonsburg, PA) to develop an interface that links the ANSYS finite-element package to Computervision's CADDS 5 modeler.

"If we can get the designer more involved in the stress side of things we are going to save a fair bit of time in the product development process," says John Rang, business systems specialist with IPG.

Ultimately, engineers will use ANSYS to verify whether stresses fall within certain high and low values. If the stress values produced exceed the predefined limits, the design will be moved to analysis. However, Rang says, "We have to get the designers involved in doing quick health checks on products as an intrinsic part of the CAE process."

One of the first groups to use the integrated CADDS 5 and ANSYS application is Clarke Chapman Marine Ltd. The Rolls-Royce IPG company makes marine deck equipment such as winches and cranes.

Clarke engineers design this equipment primarily in 2-D using Medusa software from Computervision. Once a design is complete and the drawings made, analysis is done in ANSYS. Now, designs are evaluated primarily with elastic analysis under pressure and loads, although some nonlinear buckling analysis is done. Since this type of analysis works best in 3-D, the full 3-D model is recreated within ANSYS, a time-consuming process.

The company hopes to speed design time by having only a single entry point for the 3-D model--the design stage. "We should save a third to half the time we spend currently developing the finite-element model, perhaps more," says Syd Addison, project manager at Clarke. This extra time might not decrease time-to-market, but Addison believes it will allow engineers to explore more design options.

Solid Edge 3.5 enters new CAD territory

Office 97-compatible, Solid EdgeTM Version 3.5 from Intergraph (Huntsville, AL) features the ability to model sheet-metal parts. Flat pattern, draft, and assembly capabilities are now included, along with tab, flange, contour flange, and break corner tools.

New rendering capabilities include colored lights, anti-alias options, reflections, textures, background images, and shadows.

Solid Edge's Pathfinder navigation tool makes it easier to manage assembly relationships. An assembly layout environment provides a more intuitive top-down design approach, and 'swept' and 'lofted' feature commands enable engineers to model more complex part geometries. The software also produces CGM files that can be viewed with popular Internet browsers, permitting users to share design data over the Internet and an intranet.

Also of note: support for "from scratch" 2-D geometry creation and mechanical-specific drawing composition, dimensioning, and annotation tools. This enables engineers to create a design in 3-D and detail the work in 2-D; 2-D geometry added to the drawing is associative to the drawing view from the 3-D model.

For more information on Solid Edge 3.5, visit

Products to watch

CAD for NT

CADDS(r) 5 parametric solid modeling software is now available for Windows NT(r). Compatible with UNIX-based CADDS 5, this software features an easy-to-use, object-based 3-D sketcher and parametric modeling enhancements in filleting, shelling, draft angles, history editing, and feature suppression. The software works with all Intel Pentium and Digital Alpha-based NT computers.

Computervision Corp., 100 Crosby Dr., Bedford, MA 01730, FAX (617) 275-2670.

Test-drive CAD CD

Toolbox products for AutoCAD and the Autodesk Mechanical Desktop are available for a 30-day test drive. A CD includes Toolbox for 2-D mechanical design and drafting with AutoCAD, Toolbox Professional for 3-D mechanical design and drafting with the Autodesk Mechanical Desktop, Toolbox/SM for solid sheet metal unfolding with the Mechanical Desktop or AutoCAD R13, and Toolbox/WD for ladder diagram design and drafting with AutoCAD.

CIMLOGIC Inc., 2 Wellman Ave., Nashua, NH 03060, FAX (603) 595-0381.


MiniCAD 7 is a full 32-bit cross-platform application for both Macintosh and PC systems. Solids modeling functionality allows for the union, difference, and intersection of 3-D shapes. Other features include 2-D enhancements, and the Smart Cursor, which allows for precise alignment by displaying where the cursor is in relation to the drawing. MiniCAD 7 supports Apple's QuickDraw 3-D rendering technology and associated plug-ins.

Diehl Graphsoft Inc., 10270 Old Columbia Rd., Columbia, MD 21046, FAX (410) 290-8050.

Viewing software

SolidView 2.1 lets anyone who has access to a Windows PC not only view designs, but measure and add annotations to communicate design issues. Solid View uses STL files generated from CAD systems and can import VRML data. Its publishing feature enables users to send a free viewer along with their designs, allowing communication with organizations that do not have Solid View. Users can also view 3-D face information in DXF format, and OBJ files generated from various concept modeling systems.

Solid Concepts, 28231 Avenue Crocker, Unit 110, Valencia, CA 91355, FAX (805) 257-9311.

Cost estimation

SEER-DFM 3.0 is a " part and process cost designer." Once the user identifies part, assembly, and manufacturing parameters, the software indicates the required process time and materials, and generates the unit costs for any operation. SEER-DFM can evaluate and compare design, material, and process alternatives.

G.A. SEER Technologies, 100 N. Sepulveda Blvd., Suite 1801, El Segundo, CA 90245, FAX (310) 414-3220.

Analysis software

Accupak/PE combines kinematics, rigid/flexible body dyamics, and non-linear stress analysis in a single package. The software simultaneously analyzes mechanical events involving large-deformation, non-linear material properties, kinematic motion, forces caused by motion, and stress prediction. Features include: live monitoring, optional bandwidth, and automatic contact/bounce.

Algor Inc., 150 Beta Dr., Pittsburgh, PA 15238; FAX: (412) 967-2781.

On CD: Analysis Opportunities

Leading software technologists present their views on trends and opportunities for computer-aided engineering (CAE) analysis on the CAE Round Table Forum CD. The disk includes sample solutions to a wide range of industrial design challenges, such as a metal profile rolling simulation. Several industries are represented, including automotive, chemical processing, consumer products, power generation, and metals processing. The CAE examples vary in application complexity, covering nonlinear response, structural dynamics, computational fluid dynamics, and design optimization.

Silicon Graphics Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94043.

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