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

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 new products. At the same time, market trends are driving software suppliers to release new and easier packages for computer-aided design, manufacturing, and analysis. This software runs on operating systems designed not only for high-performance workstations, but for personal computers (PCs) as well. This confluence of supply and demand has created enormous opportunities - and medical device manufacturers appear to be taking advantage of them. "We seem to be getting just as strong an interest [in our software] from medical device folks as from aerospace and other industries," says William Sprague, vice president of implementation services at Boothroyd-Dewhurst, Inc. (Wakefield, RI), a vendor of computer-aided engineering (CAE) software.

The automotive, aerospace, and consumer electronics industries have long been avid users of computer-aided design and manufacturing (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 U.S. industries have already made. "People tend to get interested [in CAD/CAM and CAE] when they come under more competitive 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 Equipment Corp. (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 engineering marketplace, 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. "We are trying to bring the product to as many people as we possibly can," says Sal Caruso, product marketing manager for Concentra's ICAD System package. "Although the product was developed for UNIX-based computers, the Windows NT platform 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 Bentley Systems, Inc. (Exton, PA). Its full-featured two-dimensional (2-D) and three-dimensional (3-D) CAD package, which allows design, analysis, drafting, database management, modeling, and visualization, was originally developed for use on high-performance workstations. Today, the CAD software runs on PCs and UNIX-based workstations. Bentley has even gone a step further, supporting its software to run on 16-bit operating systems, such as DOS and Windows, and on 32-bit systems, such as OS/2 Warp Connect and Windows NT. "Since our users are involved in large-scale engineering projects, the ability to choose the right combination of hardware platforms and operating systems is of strategic importance to their workflow," 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 graphics library, 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 its MicroStation (Version 5.5) runs efficiently in the Windows 95 operating system. The key consideration, Abrams says, is to leverage 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 virtual address 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-cavity mold.

In addition to benefiting from the development of PC-compatible CAD/CAM software packages, the medical device industry also stands to profit from the wave of consolidation under way among software vendors in search of a new range of functions, from design through manufacturing. This year alone, two major vendors of CAD/CAM software have acquired competitors in order to strengthen their product lines.

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

Similarly, France-based software vendor Matra Datavision (U.S. headquarters, Andover, MA) has acquired another French software vendor, Cisigreph (Vitrolles, France). Matra intends to use technology built into Cisigreph's STRIM Professional Solutions product to upgrade its own well-regarded Euclid software. Matra also received help from an international effort by the Industrial Advisory Board, composed of representatives from 25 companies active in a wide range of mechanical engineering and manufacturing areas. This merger of corporate and technological know-how has led to a new product, called Euclid Designer, which is scheduled for commercial release in November. The product features an object-oriented user interface with an on-line, multimedia help function. "We don't foresee any of our customers really staying with Euclid-3 after this 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) has been using Euclid-3 to design its medical products. One device developed and recently upgraded with it is the company's blood gas and critical analyte system. "Most development costs are a function of time," says David Chesley, senior mechanical engineer at Ciba Corning. Recently, when developing the product's newest add-on module, a carbon monoxide oximeter, "we were 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 of time "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 long learning 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 on an 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 will flip 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 simple diagrams to complete, step-by-step videos. The new product will also allow users to create complex models rapidly and intuitively 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, the Pro/ENGINEER package offered by Parametric Technology. Pro/E, as it is often called, has been used in the development of a wide range of devices, from a medical sonography system to a pocket inhaler. It can run on high-end computers such as the VAX 8530, or on workstations running Windows NT. Data generated by it can be shipped around the world from one engineering 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 the advanced engineering group at Baxter Healthcare (Deerfield, IL). "We transfer these intelligent computer models from country to 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 ensures that 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. Similar enhancements 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 design developed 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 a streamlined 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 CNC programmers, and basically improved the overall productivity."

That emphasis on enhancing productivity is apparent in other upgrades made to Pro/E, particularly Pro/PDM, which Giaconia describes as the "glue that holds everything together." Pro/PDM allows a number of team members to access and modify product data simultaneously without interfering with one another. This module coordinates concurrent modifications, ensuring that 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 new functionality, but that we make things work faster and more easily for them," says Jennifer Hetrich, product line manager at Parametric 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 medical device 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 David Meeker, an engineer at DEC who also serves as an independent consultant specializing in CAD/CAM and CAE. E-PAC technology, which was developed by Hewlett-Packard and is licensed to Tuscarora, Inc. (New Brighton, PA), uses expanded polypropylene foam, commonly used as a packing material, as an assembly chassis for electronic devices. E-PAC eliminates the screws and snap-on fasteners traditionally used to secure components. Instead, these parts are foam mounted at a fraction of the cost of fasteners and in a way that reduces their exposure to mechanical stress. "This is a radically challenging way of making products," says Robert Cole, a sales manager for Tuscarora. While the medical device industry has not begun using this 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 of CAD/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 medical device 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's Mechanica. In December 1994, Rasna released the seventh version of the program, which consists of 10 integrated analysis applications with separate modules. Three of the analysis applications - modules for nonlinear, buckling, and load analysis - are new 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 elbow joint, says George Henry, senior implementation specialist with Parametric Technology. The ability to predict buckling of a plate outside a plane might come in handy when designing a component that holds two bones together, for example. It might be necessary to increase the thickness of the plate, not so much for strength, but to prevent buckling. And factoring in loads helps evaluate 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 quickly incorporate modifications. Lectus, Inc. (Redwood City, CA), did just that. Rather than develop a physical prototype of a multiposition hospital bed with a lightweight frame, which would have required weeks of kinematic simulation and structural analysis, the company used Mechanica to create a computer-generated prototype. Mechanica allowed Lectus to cut its time to market 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 product families. The goal is to produce a digital design automation tool set that can take the user from product concept through manufacturing.


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

DFMA predicts the costs for assembly and manufacture of device designs, even in the early stages of development. "Not only do the engineers get a prediction of cost, but they understand what the cost drivers are, and the effect they can have by cleaning 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 both UNIX-based systems and PCs running Windows. Engineers can transfer design data they have developed using CAD/CAM programs directly into the DFMA package, which integrates design methodology with a database of costs. "You answer a series of questions about the parts going into the design and the potential difficulties in assembling or manufacturing them and the computer bounces them off the database to tell you what your costs will be," Sprague says. The software can also identify redundancies that can be eliminated or ways to design parts with multiple functions. The result can be less material, fewer suppliers, and reduced documentation.

DFMA-generated analysis can also be applied to competitors' products as part of benchmarking - the practice of analyzing competitors' products and processes and incorporating the best ideas into one's own efforts. "A company can tear down its competitors' products and get a comparison of the number of parts within and the cost of making them. They can get a feel for the 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 product development team and your goal is to beat a competitor that has a machine out right now, in a year you're going to miss that target 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, Meeker emphasizes. "Even the industry leaders need to benchmark continually to keep pace with what the competition is doing and how manufacturing and products themselves are changing." DFMA software provides a tool for systematically quantifying key manufacturing 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 has already proven its worth. Boothroyd-Dewhurst's DFMA package allowed Respironics (Murrysville, PA) to evaluate and verify part designs and perform limited testing of a manual resuscitator, called BagEasy III. Laser-sintered parts were used to evaluate assembly operations, determine fixture requirements, and revise production process configurations. Michael Donoghue, a manufacturing engineer in concurrent engineering at Respironics, notes that design verification and process validation must be completed using actual production processes, parts, and materials. But DFMA helped meet FDA requirements in two very important, indirect ways, he says. "We used the computer output to look at the whole process development and to verify their assembly processes. The Boothroyd-Dewhurst package also had an impact on the effort needed to qualify the process, because when you cut the part count by 60%, as we did on this project, you reduce the documentation 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 allows the 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 pay the 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 its users and allows decision making that considers a range of factors and perspectives. Concentra has developed a knowledge-based package called The ICAD System, which has proven useful in the aerospace and construction industries by integrating historical data about manufacturing with information about best practices and government regulations. The same potential for saving time and money exists for medical device manufacturers. "Most engineering problems are not strictly geometry-based," says Caruso of Concentra. "There are a lot of nongeometric information and rules that go into problem solving."

As a knowledge-based system, ICAD captures what the company has learned over time. Otherwise, a company risks losing this knowledge as its employees move on. "A lot of the old engineers are walking out the door with a lot of expertise," Caruso says. "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 corrosive resistance 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 to tailor the system to its specific needs. Caruso describes ICAD as essentially a tool kit, one that can be configured to fit exactly the environment of the company that uses it. "We do not come into a company and tell them how to run their business," he says. "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 of their products to customers. Structural Dynamics Research Corp. (SDRC; Milford, OH) has allied with an engineering consulting firm, Dynamic Computer Resources, Inc. (DCR; San Dimas, CA), to bring to market a turnkey solution for surgical planning and medical manufacturing. That solution involves transforming medical imaging data, processed by DCR's data conversion 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 produced with I-DEAS software, however, go well beyond these standard reconstructions. Surgeons can use the solid modeling software to plan operations, researching a library of plates, pins, and screws to determine which hardware is best suited to the task.

Most impressively, the customized software can be used to predict surgical outcomes. For example, a custom-made 3-D model can be developed showing the lower extremities and pelvis, and can then be animated to give a visual representation of pre- and postoperative gaits. "With the preoperative planner, we can determine the best method of correcting the bone deformity and be able to predict postoperative gait implications," says Richard Reynolds, MD, assistant professor of orthopedics 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 modify significantly the I-DEAS software. "You really can't throw a CAE package at a physician," says Reagan Kee, DCR's director of sales. "The surgeon needs some of those tools but not all of them." In tailoring a CAD package for the surgeon, the company limited the number of CAD tools displayed as icons on the screen - although all the CAD tools are available if needed. The interface was also adjusted to make the surgeon more comfortable. "Doctors don't deal in x, y, and z planes, they deal in sagittal, corneal, and axial planes," Kee says. "So we have given them icons with a little man facing them, a bird's-eye view 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 to customize devices for individual patients. With 3-D data, hip replacements, artificial limbs, and other prostheses would fit more exactly, improving the comfort and rehabilitation of the patient. Another potential market comprises cosmetic surgeons. "We can use laser scans and get them into I-DEAS Master Series and compare a laser scan and a computed tomography scan to show 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 meets the 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 other applications. But you still have engineers and designers going through the thought processes and trying to optimize their designs and 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 Canon Communications, 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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