CAD/CAM and Beyond: New Engineering Software Opens Doors for Medical Device Manufacturers

October 1, 1995

18 Min Read
CAD/CAM and Beyond: New Engineering                      Software Opens Doors for Medical Device

Medical Device & Diagnostic Industry Magazine | MDDI Article Index

Originally published October 1995

by Greg Freiherr

Economic forces are pushing medical device designers to rely increasingly on computers to assist in the development of newproducts. At the same time, market trends are driving software suppliers to release new and easier packages forcomputer-aided design, manufacturing, and analysis. This software runs on operating systems designed not only forhigh-performance workstations, but for personal computers (PCs) as well. This confluence of supply and demand has createdenormous opportunities - and medical device manufacturers appear to be taking advantage of them. "We seem to be gettingjust as strong an interest [in our software] from medical device folks as from aerospace and other industries," says WilliamSprague, vice president of implementation services at Boothroyd-Dewhurst, Inc. (Wakefield, RI), a vendor of computer-aidedengineering (CAE) software.

The automotive, aerospace, and consumer electronics industries have long been avid users of computer-aided design andmanufacturing (CAD/CAM) and CAE software, but only recently has the medical device industry taken a strong interest.Stricken by declining margins and heightened competition, it now appears motivated to make the leap that other major have already made. "People tend to get interested [in CAD/CAM and CAE] when they come under morecompetitive pressure," Sprague says.


The medical device industry's interest in CAD/CAM and CAE could not have come at a better time. Traditionally,CAD/CAM and CAE programs required high-priced computer workstations made by companies such as Digital EquipmentCorp. (DEC; Maynard, MA), Hewlett-Packard (Palo Alto, CA), IBM Corp. (Armonk, NY), Silicon Graphics, Inc.(Mountain View, CA), and Sun Microsystems, Inc. (Mountain View, CA). But to tap the true potential of the engineeringmarketplace, software vendors increasingly recognize that they must offer software that can be run on PCs.

Concentra Corp. (Cambridge, MA), for example, is developing a version of its CAD/CAM software for Windows NT. "Weare trying to bring the product to as many people as we possibly can," says Sal Caruso, product marketing manager forConcentra's ICAD System package. "Although the product was developed for UNIX-based computers, the Windows NTplatform has advanced to a point where we can provide solutions that run on it."

Another premier CAD company that is enthusiastic about shifting CAD software to lower-cost computer platforms is BentleySystems, Inc. (Exton, PA). Its full-featured two-dimensional (2-D) and three-dimensional (3-D) CAD package, which allowsdesign, analysis, drafting, database management, modeling, and visualization, was originally developed for use onhigh-performance workstations. Today, the CAD software runs on PCs and UNIX-based workstations. Bentley has evengone a step further, supporting its software to run on 16-bit operating systems, such as DOS and Windows, and on 32-bitsystems, such as OS/2 Warp Connect and Windows NT. "Since our users are involved in large-scale engineering projects, theability to choose the right combination of hardware platforms and operating systems is of strategic importance to theirworkflow," says company president Greg Bentley.

Despite this flexibility, the operating system of choice for Bentley and others has been Windows NT. Michael Abrams,associate editor of the newsletter CAD Report, explains that Windows NT allows multitasking and includes a 3-D graphicslibrary, called Open GL, which is based on a graphics library developed by Silicon Graphics.

The introduction of Windows 95 could lead vendors to expand their horizons further still. Bentley Systems, for example,recently posted a note on the Internet stating that "every effort is being made to ensure" that the latest release of itsMicroStation (Version 5.5) runs efficiently in the Windows 95 operating system. The key consideration, Abrams says, is toleverage a 32-bit operating environment: "It has a lot to do with address space. Computer graphics are very memory-intensive.A 32-bit operating system provides billions of possible addresses, so you are not constantly swapping things into virtualaddress space, like you do in Windows 3.1. Swapping stuff into lower memory is why systems crash."


Image: Pro/ENGINEER CAD/CAM software reveals the core side of a two-cavitymold.

In addition to benefiting from the development of PC-compatibleCAD/CAM software packages, the medical device industry also stands toprofit from the wave of consolidation under way among software vendors insearch of a new range of functions, from design through manufacturing. Thisyear alone, two major vendors of CAD/CAM software have acquiredcompetitors in order to strengthen their product lines.

On August 2, Parametric Technology Corp. (Waltham, MA) completed itsacquisition of Rasna Corp. (San Jose) and formally began integrating Rasna's premier CAE product, called Mechanica, into itsown product line. On the day the deal was completed, Steven Walske, chairman and CEO of Parametric Technology, statedthat "closer integration of these technologies will create synergistic benefits for customers by allowing them to design betterproducts faster and more cost-effectively." That sentiment was echoed by George Henry, a Rasna cofounder, who has joinedParametric Technology as senior implementation specialist. "Parametric Technology's Pro/Engineer is an advancedCAD/CAM tool, and we provide a CAE tool," Henry says. "It's a match made in heaven in terms of complementaryproducts."

Similarly, France-based software vendor Matra Datavision (U.S. headquarters, Andover, MA) has acquired another Frenchsoftware vendor, Cisigreph (Vitrolles, France). Matra intends to use technology built into Cisigreph's STRIM ProfessionalSolutions product to upgrade its own well-regarded Euclid software. Matra also received help from an international effort bythe Industrial Advisory Board, composed of representatives from 25 companies active in a wide range of mechanicalengineering and manufacturing areas. This merger of corporate and technological know-how has led to a new product, calledEuclid Designer, which is scheduled for commercial release in November. The product features an object-oriented userinterface with an on-line, multimedia help function. "We don't foresee any of our customers really staying with Euclid-3 afterthis product comes out," says Judy Wetzler, Matra's director of marketing communications.

That is not to say that the software does not have a strong following. For several years, Ciba Corning (Medfield, MA) hasbeen using Euclid-3 to design its medical products. One device developed and recently upgraded with it is the company'sblood gas and critical analyte system. "Most development costs are a function of time," says David Chesley, senior mechanicalengineer at Ciba Corning. Recently, when developing the product's newest add-on module, a carbon monoxide oximeter, "wewere able to go from concept to working prototypes in about two months using Euclid," he says.

The manufacturing side of Ciba Corning, says Beth Bauman, operations manager for the company's instrument/sensors unit,has been very pleased with the results of the software. What she and her colleagues have not been happy about is the length oftime "it takes for somebody to get good at running the software. That has been pretty frustrating for us," says Bauman.

Matra's Wetzler acknowledges the problem. "Euclid is one of the most sophisticated systems in the industry, it has a longlearning curve, and it is a bit cumbersome to use," she says. But that should change with the introduction of the new product."With Euclid Designer, everything is on-line and context-sensitive," Wetzler explains. "If you reach a problem, you can click onan icon and a guy will come up on your screen and talk you through it, or you can click on a little notebook and the screen willflip right to the section you need."

That guy is part of a computer-stored, multimedia helper that gives instant access to assistance that ranges from simplediagrams to complete, step-by-step videos. The new product will also allow users to create complex models rapidly andintuitively from a set of simplified menus.

Despite these enhancements, Euclid will have to fight hard to supplant the industry's number one CAD/CAM program, thePro/ENGINEER package offered by Parametric Technology. Pro/E, as it is often called, has been used in the development ofa wide range of devices, from a medical sonography system to a pocket inhaler. It can run on high-end computers such as theVAX 8530, or on workstations running Windows NT. Data generated by it can be shipped around the world from oneengineering lab to another - or run in private design houses.

"Pro/Engineer's solid models are a universal language," says Michael McEvoy, vice president of technical tools for theadvanced engineering group at Baxter Healthcare (Deerfield, IL). "We transfer these intelligent computer models from countryto country, for our divisions to make tools."

Pro/E links seamlessly with modules such as Pro/MolDesign, which is optimized for injection molding. Pro/MolDesign ensuresthat calculations made in Pro/E are correct and that all of the cavities on the molds are properly aligned.

The most recent version of Pro/MolDesign includes an improved user interface aimed at increasing productivity. Similarenhancements were incorporated into Version 15 of Pro/Manufacturing, which is also designed for manufacturing applications,but in computer numerical control (CNC) programming. The two modules might be used in tandem, with a mold designdeveloped on one and machined on the other.


"We have a lot of major companies out there that are embracing this technology - that want to use it - and they want astreamlined user interface," says Paul Giaconia, product line manager for manufacturing applications at Parametric Technology."To make Pro/MANUFACTURING easier to use, we reduced menu choices, used terminology common to CNCprogrammers, and basically improved the overall productivity."

That emphasis on enhancing productivity is apparent in other upgrades made to Pro/E, particularly Pro/PDM, which Giaconiadescribes as the "glue that holds everything together." Pro/PDM allows a number of team members to access and modifyproduct data simultaneously without interfering with one another. This module coordinates concurrent modifications, ensuringthat the integrity of the files and database are preserved. The third release of this module was introduced commercially in May,and its primary focus was on speed and ease of use. "Our customers have demanded not so much that we add newfunctionality, but that we make things work faster and more easily for them," says Jennifer Hetrich, product line manager atParametric Technology. "That's what we focused on in release three."

The market, says Hetrich, is "very young, very huge, and very open." Using CAD/CAM and CAE packages enables medicaldevice manufacturers to step through doors that would otherwise be closed to them.

E-PAC (electronics packaging assembly concept) is a "solution just waiting for the medical guys" to discover, says DavidMeeker, an engineer at DEC who also serves as an independent consultant specializing in CAD/CAM and CAE. E-PACtechnology, which was developed by Hewlett-Packard and is licensed to Tuscarora, Inc. (New Brighton, PA), uses expandedpolypropylene foam, commonly used as a packing material, as an assembly chassis for electronic devices. E-PAC eliminatesthe screws and snap-on fasteners traditionally used to secure components. Instead, these parts are foam mounted at a fractionof the cost of fasteners and in a way that reduces their exposure to mechanical stress. "This is a radically challenging way ofmaking products," says Robert Cole, a sales manager for Tuscarora. While the medical device industry has not begun usingthis technology, Hewlett-Packard has, specifically in the manufacture of its UNIX-based workstation, the HP 712/60.

"E-PAC is phenomenally cheaper than anything else out there," Cole says. The key to using it, he says, is the application ofCAD/CAM software. "All you do is put the parts up on the screen and just start playing with the arrangement of those parts,"he adds.


CAD/CAM represents just one side of the computer revolution, however. Another side is what the computer offers medicaldevice manufacturers as they analyze those designs. And that is where the computer really shines.

Typically, designs are created using CAD/CAM software and then tested using CAE software. One such program is Rasna'sMechanica. In December 1994, Rasna released the seventh version of the program, which consists of 10 integrated analysisapplications with separate modules. Three of the analysis applications - modules for nonlinear, buckling, and load analysis - arenew and have special significance for medical device manufacturers.

Nonlinear contact analysis predicts where deformation of two parts might occur, as in the case of modeling a knee or elbowjoint, says George Henry, senior implementation specialist with Parametric Technology. The ability to predict buckling of aplate outside a plane might come in handy when designing a component that holds two bones together, for example. It might benecessary to increase the thickness of the plate, not so much for strength, but to prevent buckling. And factoring in loads helpsevaluate how the distribution of forces will affect a structure.

The Mechanica software offers immediate feedback to the user. Engineers can evaluate their designs on-screen, and quicklyincorporate modifications. Lectus, Inc. (Redwood City, CA), did just that. Rather than develop a physical prototype of amultiposition hospital bed with a lightweight frame, which would have required weeks of kinematic simulation and structuralanalysis, the company used Mechanica to create a computer-generated prototype. Mechanica allowed Lectus to cut its time tomarket in half.

Mechanica can be integrated seamlessly with a variety of CAD packages, most notably Parametric Technology's Pro/Engineer- which provided the basis for the acquisition. Parametric Technology is now in the process of integrating the two productfamilies. The goal is to produce a digital design automation tool set that can take the user from product concept throughmanufacturing.


Even after that integration is complete, Parametric Technology will not offer every type of software that can be used in productdesign and development. Another software type, called design for manufacturing and assembly (DFMA), has the power toanswer questions that no other software can approach - questions that can mean the difference between the success or failureof a product.

DFMA predicts the costs for assembly and manufacture of device designs, even in the early stages of development. "Not onlydo the engineers get a prediction of cost, but they understand what the cost drivers are, and the effect they can have bycleaning up the design versus other aspects of the process," says Sprague of Boothroyd-Dewhurst.

Companies are already taking advantage of DFMA software. Boothroyd-Dewhurst's DFMA product runs on bothUNIX-based systems and PCs running Windows. Engineers can transfer design data they have developed using CAD/CAMprograms directly into the DFMA package, which integrates design methodology with a database of costs. "You answer aseries of questions about the parts going into the design and the potential difficulties in assembling or manufacturing them andthe computer bounces them off the database to tell you what your costs will be," Sprague says. The software can also identifyredundancies that can be eliminated or ways to design parts with multiple functions. The result can be less material, fewersuppliers, and reduced documentation.

DFMA-generated analysis can also be applied to competitors' products as part of benchmarking - the practice of analyzingcompetitors' products and processes and incorporating the best ideas into one's own efforts. "A company can tear down itscompetitors' products and get a comparison of the number of parts within and the cost of making them. They can get a feel forthe technologies and the nonrecurring tooling costs - everything that's involved," Sprague explains.

According to consultant Meeker, companies use benchmarking to get the jump on the competition. "If you're a productdevelopment team and your goal is to beat a competitor that has a machine out right now, in a year you're going to miss thattarget if you haven't examined the direction they're taking," he says.

Benchmarking is not practiced solely by companies that aspire to be leaders - it is done by the leaders themselves, Meekeremphasizes. "Even the industry leaders need to benchmark continually to keep pace with what the competition is doing andhow manufacturing and products themselves are changing." DFMA software provides a tool for systematically quantifying keymanufacturing indices, providing an objective basis for making strategic design decisions.


CAD/CAM and CAE software can also help companies meet the documentation requirements of FDA. Here DFMA hasalready proven its worth. Boothroyd-Dewhurst's DFMA package allowed Respironics (Murrysville, PA) to evaluate andverify part designs and perform limited testing of a manual resuscitator, called BagEasy III. Laser-sintered parts were used toevaluate assembly operations, determine fixture requirements, and revise production process configurations. MichaelDonoghue, a manufacturing engineer in concurrent engineering at Respironics, notes that design verification and processvalidation must be completed using actual production processes, parts, and materials. But DFMA helped meet FDArequirements in two very important, indirect ways, he says. "We used the computer output to look at the whole processdevelopment and to verify their assembly processes. The Boothroyd-Dewhurst package also had an impact on the effortneeded to qualify the process, because when you cut the part count by 60%, as we did on this project, you reduce thedocumentation required by at least 60%."

DFMA makes use not only of engineering data, but of human expertise as well. It follows the rules of engineering, but allowsthe engineer to decide when those rules should be bent. "It's the old story of a camel being a racehorse designed by committee.The committee followed all the do's and don't's but ended up with something completely nonfunctional," Sprague says."Bending or breaking rules usually involves an associated cost. If you understand what that is, sometimes you are willing to paythe penalty because of the benefits you receive."

Software that allows such reasoning is said to be knowledge-based, because it captures the experiences and practices of itsusers and allows decision making that considers a range of factors and perspectives. Concentra has developed aknowledge-based package called The ICAD System, which has proven useful in the aerospace and construction industries byintegrating historical data about manufacturing with information about best practices and government regulations. The samepotential for saving time and money exists for medical device manufacturers. "Most engineering problems are not strictlygeometry-based," says Caruso of Concentra. "There are a lot of nongeometric information and rules that go into problemsolving."

As a knowledge-based system, ICAD captures what the company has learned over time. Otherwise, a company risks losingthis knowledge as its employees move on. "A lot of the old engineers are walking out the door with a lot of expertise," Carusosays. "Companies need to capture these best practices in a way that is reusable. The ICAD System can do that."

It can also do much more. "Rules of thumb as to when you apply materials and under what circumstances, the corrosiveresistance of a material, what kind of life can be expected from a material - these can all be captured in a materials library,"Caruso says.

As opposed to simply selling and training company staff to use a software package, Concentra works with the company totailor the system to its specific needs. Caruso describes ICAD as essentially a tool kit, one that can be configured to fit exactlythe environment of the company that uses it. "We do not come into a company and tell them how to run their business," hesays. "They know that. We help them automate what they know."


As applications become more widespread in the health-care industry, vendors must deliver ever more customized versions oftheir products to customers. Structural Dynamics Research Corp. (SDRC; Milford, OH) has allied with an engineeringconsulting firm, Dynamic Computer Resources, Inc. (DCR; San Dimas, CA), to bring to market a turnkey solution for surgicalplanning and medical manufacturing. That solution involves transforming medical imaging data, processed by DCR's dataconversion program, into 3-D solid models using SDRC's I-DEAS Master Series software.

Generating 3-D models of in vivo tissue has been commonplace for the better part of a decade. The models being producedwith I-DEAS software, however, go well beyond these standard reconstructions. Surgeons can use the solid modelingsoftware to plan operations, researching a library of plates, pins, and screws to determine which hardware is best suited to thetask.

Most impressively, the customized software can be used to predict surgical outcomes. For example, a custom-made 3-Dmodel can be developed showing the lower extremities and pelvis, and can then be animated to give a visual representation ofpre- and postoperative gaits. "With the preoperative planner, we can determine the best method of correcting the bonedeformity and be able to predict postoperative gait implications," says Richard Reynolds, MD, assistant professor oforthopedics at the USC School of Medicine and an orthopedic surgeon at Children's Hospital of Los Angeles.

The key to the acceptance of this product by medical practitioners is ease of use. Recognition of that fact led DCR to modifysignificantly the I-DEAS software. "You really can't throw a CAE package at a physician," says Reagan Kee, DCR's directorof sales. "The surgeon needs some of those tools but not all of them." In tailoring a CAD package for the surgeon, thecompany limited the number of CAD tools displayed as icons on the screen - although all the CAD tools are available ifneeded. The interface was also adjusted to make the surgeon more comfortable. "Doctors don't deal in x, y, and z planes, theydeal in sagittal, corneal, and axial planes," Kee says. "So we have given them icons with a little man facing them, a bird's-eyeview of the little man, and a little man sideways."

The primary market for the integrated system is the orthopedic surgeon, but manufacturers of implants could also use it tocustomize devices for individual patients. With 3-D data, hip replacements, artificial limbs, and other prostheses would fit moreexactly, improving the comfort and rehabilitation of the patient. Another potential market comprises cosmetic surgeons. "Wecan use laser scans and get them into I-DEAS Master Series and compare a laser scan and a computed tomography scan toshow what implants need to be manufactured for surgical reconstruction," Kee notes.


A major determinant of whether CAD/CAM and CAE software succeeds in the medical device industry is how well it meetsthe needs of users. As an industry source noted, simply throwing a chain saw into the woods does not produce two-by-fours.There has to be a concerted effort to apply this software to medical device applications. "Software is a productivity tool,"explains Giaconia of Parametric Technology. "You can capture engineers' knowledge and reuse that knowledge on otherapplications. But you still have engineers and designers going through the thought processes and trying to optimize their designsand reduce the costs."

Greg Freiherr is a contributing editor for MD&DI.

(This article originally appeared in the October 1995 issue of Medical Device & Diagnostic Industry. © 1995 CanonCommunications, Inc. All rights reserved. The initial photo is courtesy of DeRoyal Plastics Group. The Pro/ENGINEER photois coutesy of Jones Plastic Engineering.)

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