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Articles from 1995 In November


Vendors build in ease of use

Vendors build in ease of use

With its dual emphasis on precision and cost effectiveness, electronic motion control has moved from being a bit player to a major force in industry. Today, it is critical technology in machine tools, packaging, and robotics. Tomorrow, say its advocates, it will be just as critical in a wide range of other industries, particularly those that require speed and efficiency on the factory floor.

To find out what the major breakthroughs are likely to be in electronic motion control as we approach a new century, Design News talked to several suppliers and users. You'll read their assessments in the next few pages, as well as one industry leader's views on tomorrow's motion-control systems.

The controller stands alone

Ease of use has become a defining characteristic of electronic motion control. Engineers at Galil Motion Control expect that to continue being the case well into the next century, with most of the growth of the technology occurring in less sophisticated markets. "When we started introducing products that plugged into a PC, we began to see ordinary electrical engineers as customers, physicists as customers, and technicians as customers," says Jacob Tal, president of the Sunnyvale, CA, company.

There exist two different philosophies concerning PC-based motion controllers. One is to rely on the PC to perform a portion of the processing. The other--the one preferred by Galil and competitor Delta Tau Data Systems (Northridge, CA)--is to make the motion controller so smart that it can stand alone. The link to the PC is for communication, not processing. "We really do this because it is easier to diagnose if something goes wrong, not because it is inherently more powerful," Tal says.

Today, Galil's new third-generation controllers take ease of use--and capability and performance--one notch higher. The product line consists of three devices, the DMC-1000, DMC-1300, and DMC-1500. Each is identical in capability, but the 1000 plugs into a PC, the 1300 targets VME-bus machines, and the 1500 is a stand-alone controller.

While the company may be touting ease-of-use, these third-generation controllers aren't slouches. All offer control of one to eight axes, including step motor, servo, or hydraulics. A 32-bit microprocessor and a custom sub-micron gate array give them four times the speed of their predecessors. Encoder feedback can be as high as 8 MHz, sample rates may be as short as 125aesec, and RS232/RS422 communication reaches 38.4K baud. And in the case of the DMC-1500, it's half the size and 40% cheaper than the previous generation DMC-700.

Modes of motion include the usual jogging, linear and circular interpolation, and contouring. It also includes electronic gearing--the ability to synthetically gear up to eight axes with variable ratios between them--and electronic camming--the synchronization of up to seven axes with a master axis to simulate the motion of a mechanical cam.

One company that agrees with Galil's vision of motion control is Glasstech (Perrysburg, OH). The firm's line of glass bending and tempering systems operate in 50 countries on six continents and are responsible for producing 80% of the 3-mm-thick glass sidelites used in all the world's automobiles. Each of four different bending and/or annealing machines depends on two 3-axis Galil controllers. They command the servo motors that power the glass-feed conveyors and run the gear trains that control a flexible bed for shaping the glass.

"We really don't do any sophisticated motion," says Dene Rinaldo, Glasstech's senior control engineer. "We chose Galil because the cards are reliable and the programming language, while sophisticated, is easy to use."

With his products spread across the globe, Rinaldo needs to be able to troubleshoot easily over the phone. He finds that Galil's line-interpretative language can be understood by most any engineer familiar with BASIC. Program printouts can be reviewed remotely on the phone, or modifications can be sent via Compuserve's e-mail. "To spend $3,000 to fly someone halfway around the world to make a one-line change in a program is not what we want to spend time doing," he says.

"Twenty years ago when you shipped a system, you shipped an engineer with it," says Tal. "Now it's more important to have comprehensive diagnostics built in than any other function."

Reliability is also important to Glasstech, and Rinaldo has been impressed with the durability of Galil controllers. "Our machines run seven days a week, three shifts a day in a very warm environment," he says. "Our customers don't need Star Wars; they need something that is easy to use and runs for years."

Programming skills? You won't need them anymore

Traditionally, installing, programming, and debugging a motion control system has been as much black magic as engineering. Designers at Berkeley Process Control say their new MachineWorks(TM) machine controller can eliminate the hocus-pocus and greatly speed the development of motion control systems, while also increasing reliability. "It's a breakthrough in the utility of machine control," explains Steve Kraft, product development manager, "not in raw performance, but utility."

The MachineWorks concept is basic: simplify through pre-integration. Since most machine development involves integrating hardware and software, Kraft and a team of engineers at Berkeley designed MachineWorks to eliminate these steps using something they call direct machine development.(TM)

Direct machine development simplifies the traditional development process--plugging in cards, connecting possibly incompatible components, and especially, writing lines of code--by providing an organizing structure for machine control built into the system. Developers can enter complete machine-control sequences from a touchscreen, following menu prompts, without any conventional programming.

The development process involves a series of on-screen prompts and selections. A full machine database, Quickstart(TM), gives users access via the touchscreen to servo functionality, axes, I/O naming, auto-tuning, etc. All underlying issues--the black magic--of axes setup, error handling, diagnostics, and hardware configuration are anticipated.

The step-by-step process combines pre-written building blocks of optimized code into the complete debugged system. Complex operations are separated into tasks, entered via the touchscreen, and can then be executed simultaneously for true multi-tasking.

The crucial benefit is time to market. "We've done jobs that have traditionally taken six weeks, and with MachineWorks, we've done them in two or three days," says Kraft. The Apple Computer of the motion-control world, Berkeley designs all its components to work together. They are specifically machine-control components, and they integrate quickly and easily, Kraft says. And programming, the part of the job where days can slip to weeks and months, is reduced to the assembly of optimized, pre-compiled instructions via MachineWorks.

An example of MachineWorks in action appears at Meadows Manufacturing (Sunnyvale, CA). The company's problem: how to retrofit a two-year-old, four-axis product insertion machine with the least downtime and the largest increase in reliability. Engineers also wanted to convert the machine from semi-automatic to fully automatic operation.

Pedro de la Serna, project engineer at Meadows, describes the machine as an X-Y-Z table that holds a nest of pre-measured portions of a liquid product. The table repositions each portion in front of an insertion actuator that pushes the portion into individual product applicators.

The new control system consists of Berkeley Integris, which includes MachineWorks, multi-axis amplifiers, I/O system, interface, power supply, and an enclosure. As a fully integrated solution, the turn-key operation was up and running quickly--with greatly increased capability and reliability.

The largest time savings occurred in programming. With MachineWorks, the insertion machine's software was written and debugged in two days. "We took the product down to their facility on Monday and left on Wednesday with a fully functional machine--full diagnostics, everything," says Kraft. And he left the system, with complete confidence, in the hands of de la Serna, a mechanical engineer who had never seen a Berkeley Process Control product before.

Kraft stresses that his company's solution is not inflexible. With Meadows, for example, engineers defined two custom sequences using MachineWorks' Extensions option.

Only a few months into the new system, De la Serna already plans to expand the machine's capabilities. Kraft isn't surprised. "Instead of focusing on technology, performance, and numbers, we're focusing on utility," he says. "If you can't use it, it doesn't matter what the raw capability is."

Flexibility is the driver

To see where motion-control is heading, one need only look at changes in the office-automation market, says Scott Hibbard, vice president of Indramat, Wood Dale, IL. The transition from centralized mainframe computing to minicomputers to distributed, open-system PCs foreshadows developments in industrial control.

If you want to gauge the industry's progress on that path, the best place to look is the machine-tool market. "In the metal-cutting industry, multi-axis machining centers are replacing dedicated transfer lines," he explains. "But greater flexibility can't mean sacrificing production rates or machining accuracy." The technological answers to the needs of these most-demanding applications will, in Hibbard's words, "bleed down into other industries."

Indramat's latest, the DKR digital ac servo drive, highlights what's coming. Microprocessor technology makes the drive a common platform for controlling motors from fractional to 100 hp. "One drive, one software package for rotary permanent magnet, rotary induction, linear permanent magnet, and linear induction motors," recounts Hibbard. It includes electronic gearbox and cam functions, function monitoring, and real-time machine-or-drive diagnostics to simplify troubleshooting tasks and boost machine uptime.

In addition to simplifying system setup, smarter drives mean easier development work for controls manufacturers. Where different applications required different motors and thus, different drive platforms, now software developed for one application is instantly available to all. There's more functionality, and it's more widely available.

The DKR drive also includes the fiber-optic, open SERCOS communications interface. SERCOS not only reduces wiring complexity, it's a high-speed link that will enable the lowest-level distributed control that is changing the motion-control industry.

Where most people think of distributed control as PLCs or motion-control cards operating one or several motors on a machine-by-machine basis, the new model, says Hibbard, is smart drives linked by SERCOS and communicating with a much-less-harried master controller. "Any control function performed on an axis-by-axis basis is a candidate for placment in the drive itself."

There's no longer the need to control a position loop or do fast offset corrections upstream in a centralized controller, Hibbard contends. Thus, as machine controllers have less axis-control work to do, they become candidates for open architectures like PCs. "We're taking away the peculiarities of the CNC or PLC," he says.

The shift to distributed control governed by PCs will mean much less reliance on system integrators for machine programming. A user will be able to purchase packages of software and put together his or her own control system if that's their wish.

For controls makers, the shift will make success a little harder to achieve. Yet Hibbard is optimistic about the future. "There will always be advantages to choosing one piece of hardware over another," he says. "As long as your company is technology-driven, you can still stay on top of the game."

Users: Write your own interface

The advantages of higher performance that come with advances in motion-control hardware design are lost if running the new systems becomes too complicated. That's the message from Cosmo Mirra, general motion-control product manager at GE Fanuc. The opportunity exists for the "popularizaton" of high-performance electronic motion control, he says, but only for those who don't forget the users.

The core challenge facing controls makers comes from the proliferation of controller hosts available today--CNCs, PLCs, and PCs. Large industrial users of motion control, such as the auto industry, adopt the new control technologies as a requirement of staying competitive. But adding new systems alongside previous generations of controls creates problems. "They run a number of different processes and they want a common operator interface from machine to machine in order to control their training costs," explains Mirra.

Traditionally, controls manufacturers took one of two approaches to operator interfaces (OIs), continues Jeff Kao, a GE Fanuc applications engineer: Either an industry-standard look and feel as with CNC commands, or a totally open approach where users design their own screens.

For old customers like the machine-tool industry where CNC originated, a standard interface often suffices. Large industries, like automotive, usually have or can afford the programming expertise necessary to construct custom interfaces. But to expand electronic motion control into new territories, the company felt it needed a different approach to building OIs.

As part of its recently introduced PowerMotion line of high-precision, distributed-control products, GE Fanuc introduced the C Executor, a development tool that greatly simplifies creation of custom OIs.

"We compile our programs on an IBM PC using Microsoft C," explains Kao. "You load the program in, get up and running quickly, then customize the presentation of data to meet the user's needs."

For example, says Kao, a robotic painting system can be configured to go to location 1, 2, or 3 instead of the operator calling CNC coordinate codes.

One user has already seen the benefits gained from an easily customizable interface. James Rodrigues, product manager for the robotics division of Husky Injection Molding Systems, Bolton, Ontario, says PowerMotion with C-Executor could be the key to winning new customers.

Husky developed a three-axis gantry robot for materials handling to serve its molding equipment. It needed a teaching pendant to enable users to operate the system, but shied away from non-intuitive languages that customers didn't know.

"We needed to have application software that was specific to injection molding to properly market the product," explains Rodrigues. With an assist from GE Fanuc applications engineers, C Executor allowed Husky to develop a menu-driven front end that incorporates industry terminology. "We think people will like it because they can relate to it and learn it quickly." He continues, "If we had to use off-the-shelf software, customers would probably shop elsewhere."

As Mirra sums it up: "With the C-Executor, we're marrying a high-performance motion system, a descendant of complex multi-axis CNC, with an easy-to-use software tool." That's how you make motion control popular.

Designer's Corner

Designer's Corner

In-wheel drive

Wasted space. That's what you find inside most wheels. Filling the void with a compact gearmotor, therefore, makes sense when designing small, electric-powered vehicles.

Custom-built, in-wheel drives from Rockland Precision Gearmotors fully integrate the gearmotor, wheel, and chassis mount. Because the planetary gear's rotating member functions as the wheel hub, the design places vehicle weight on top of the bearings for greater load-carrying capacity.

Use of brushless DC motors, moreover, offers better efficiency, reduced maintenance, and higher power-to-size when compared to more common brush-type motors.

David Silverstein, Rockland Precision Gearmotors, 20 Seaview Blvd., Port Washington, NY 11050 (516) 625-9151.


Photon counter

Photon counting systems typically cost several thousand dollars. Not so with the HC135 Series PMT (photomultiplier tube) sensor module. Plugged to a PC via RS-232C serial interface, the self-contained system integrates all components necessary for photon counting.

Operators program integration time, number of readings, and reading sequence with the host computer. The microcontroller corrects each reading for a linear range exceeding six orders of magnitude and less than 1% nonlinear error.

Designed for medical equipment, industrial measurement systems, and analytical instruments, the modules sell for appoximately $1,800.

Craig Walling,Hamamatsu Corp., 360 Foothill Rd., Box 6910, Bridgewater, NJ 08807, (908) 231-0960.


No-leak Li battery

Within a year, Solid-State System(TM) lithium batteries should be available in quantity to supplant troublesome liquid-electrolyte lithium-ion designs. Now in development with several portable-electronics manufacturers, Ultralife(R) batteries use a solid polymer electrolyte to prevent leaks and venting of hydrogen. Energy density ranges between 100-130 W-h/kg, and the design permits prismatic configurations as thin as 0.020 inch.
Greg Smith,Ultralife Batteries, Inc., 160 Summit Plaza, Montvale, NJ 07645, (201) 930-4900.


Ice chips

It's called ice for a reason: diamond has the best thermal conductivity of any known material. Progress in chemical-vapor-deposited diamond now makes it possible to package integrated circuits with a diamond-film heat spreader that swiftly carries thermal energy out to the chip leads. A 208-pin IC with the so-called Norcool(TM) configuration recently demonstrated thermal resistance of 12.5 degrees C/W at 5W without forced cooling--that's 26% to 50% better than conventional thermally enhanced package designs.
Arjun Partha, Norton Diamond Film, Goddard Road, Northboro, MA 01532, (508) 351-7779.


Self-indexing vise

Vises that grip angled extrusions typically require the machinist to manually adjust the jaws until they conform to the extrusion. By mounting a half-cylindrical jaw insert into this vise's movable jaw, designers enable the vise to automatically adjust to workpieces of different angularities. Depending upon the application, the insert can either freely pivot in the movable jaw, or it can be biased by springs to return to a set position. During extrusion routing operations, the vise frees the machine operator from the need to make adjustments as the angles of different extrusions change.
Mark Turner or Laszlo Ferenczi, Box 655907, M/S MSF-41, Dallas, TX 75265-5907, (214) 266-2772.

PC advances drive control technology

PC advances drive control technology

The driving force behind motion control for the past 15 years, and into the foreseeable future, stems from the rapid advancement of the computer's speed, power, and cost. The good news for all of us involved with industrial control is that the computing revolution is far from over. Computers continue to move ahead in accordance with Moore's law: Their speed and power will still double every 18 months.

As its capabilities grow, the PC continues to accelerate its expansion into the industrial automation marketplace. The result: It will coordinate a growing number of control tasks by the year 2000.

But questions remain. What are we going to do with all that computing power? How will engineers overcome the obstacle holding back computer-controlled, servo-driven machinery--the enormous amount of software required to advance state-of-the-art automation systems? In short, how can we most effectively use this technology to make our companies more productive and profitable?

Electronics take the stage. To answer those questions, it may be helpful to look back a bit. In the late 1970s, microprocessor technology achieved enough power to be useful in motion-control applications. Microprocessor-controlled servomotors provided many advantages compared with other motion-control alternatives: excellent torque/speed delivery, positioning accuracy, and the ability to limit torque. In a fully microprocessor-based, servo-control system, position, torque, and velocity are regularly monitored and, in some systems, they can be read at any time by the motion controller or a supervisory computer.

Design engineers increasingly used such systems to achieve greater flexibility, operating speeds, accuracies, and reliability than ever before. In factory-automation applications, servo-based electronic motion control steadily gained ground over more traditional mechanical means of power transmission, as well as "lower-tech" drive-system alternatives, such as stepping motors and ac and dc motors.

The rapid emergence of this technology resulted in a complex and often confusing array of choices for design engineers. Some suppliers chose to focus on low-cost products for use in high-volume applications. Usually, such systems sacrifice features and performance for stringent price objectives. Other suppliers decided to provide products that push the state of the art in one technological area at the expense of another.

At ORMEC, we specialized in multi-axis applications for high-speed, line-oriented automation. We felt that such systems provide excellent servo performance with features that permit ready integration into a variety of factory-automation environments.

Until now, most automation controls have relied on proprietary hardware and software. However, end users have a growing interest in open standards. The goals: to encourage use of commercial hardware and software, eliminate non-standard interfaces, reduce integration costs, and simplify diagnostics and maintainability of the equipment.

A few months ago, a group within General Motors, Ford, and Chrysler produced a white paper that describes the requirements for various elements of an open, modular architecture controller (OMAC). The needs of automotive manufacturing applications, the paper stated, can be examined under these headings: safety and liability, life-cycle cost, flexibility, connectivity, maintenance, and training.

From a hardware and software point of view, OMAC would "encourage use of commercial standards." The controller's hardware bus structure must be a de facto standard (VMEbus or some forms of PC bus architecture, such as ISA, EISA or PCI is preferred). The human interface must support commonly accepted, easy-to-configure graphical user interfaces. IEC-1131-3 standard programming languages must be used to program discrete I/O logic.

In that light, the lure of the IBM PC-compatible architecture is understandable. It is the de facto standard and, because of its market dominance, it also commands the world's largest base of software applications.

PC controller requirements. Although the PC has made many inroads on the factory floor, it has made only limited gains in actual control. Why? Because it lacks the "industrial features" needed in any automation controller. The additional speed and power of today's and tomorrow's microprocessors will, in part, make up for those deficiencies.

Computers used in industrial control should incorporate safety and liability features such as Watchdog Timers, Emergency Stop inputs, and No-Fault outputs. These features guarantee the user that if the computer stops operating correctly, or if the emergency stop circuit trips, the No-Fault output will be released, causing the machinery to be safely stopped.

In industrial controllers, smaller and harder is better. Standard packaging in today's PLCs is panel-mounted with front-loading, removable adapter modules. Industrial controllers generally can operate in temperatures from 0 degrees to 50 degrees C and withstand substantial shock and vibration. Industrial PCs must meet the same benchmarks.

MS-DOS is a single-tasking operating system; industrial control requires multi-tasking. Industrial controllers typically incorporate highly reliable, pre-emptive, multi-tasking kernels. They provide such features at reasonably low cost, while requiring relatively modest resources, such as RAM memory.

Because of the high cost of downtime, reliability and maintainability are paramount in industrial controls. Rotating components, such as fans and disk drives, are generally regarded as the least reliable components in the system and must be avoided when possible.

Non-volatile memory provides a convenience feature long enjoyed by PLC users. This allows machine setup parameters to survive power outages without special programming efforts.

Computer's future power. In some cases, industrial computers have such features, but the price premium is often prohibitive. The combination of Moore's Law and open standards, plus the availability of commercial hardware and software, has substantially reduced that premium.

Our new ORION Series is an important step for ORMEC, but we feel these new controllers are only part of an era where the IBM-PC architecture will make significant inroads. For example, they will no doubt continue the expansion of servomotor-based control into the industrial-automation control market.

We also feel that servomotor-based motion control will grow at a healthy 8-10% per year in the general-purpose factory-auto-mation market. It will continue to displace mechanical means of power transmission due to advantages in flexibility, speed, accuracy, measurability, reliability, and cost.

Servo feedback will continue to be split among encoder- and resolver-based systems. Due to their positioning accuracy and speed of response, encoders will serve 70% of applications in the factory automation market and will be required in 30%. Resolver feedback will be used in 30% of applications and required in 10%. This use stems from such environmental factors as extreme temperatures, shock and vibration, or high levels of contaminants in and around the motor/resolver.

Open digital communications standards (such as DeviceNet(TM), Profibus, Interbus-S and Ethernet) will gain widespread acceptance in factories. This, in turn, will weaken the dominance of proprietary factory networks running on large PLCs.

What all this means is that the distinction between motion controllers and other industrial computers will become further blurred and their cost continue to gradually decrease. More significantly, they will provide substantially more power, features, and ease of use. Within the next few years, the same industrial PC-based motion controller will run multiple tasks: automation control, motion control, human-machine interface, and factory network communications.

Along with this trend, software will need to grow geometrically to provide the increased functionality and ease of use demanded by the users. This software will be provided by multiple vendors who specialize in different applications unified by cross-vendor software compatibility. Independent vendors will support operating systems, programming standards (including IEC-1131), motion control, graphical human-machine interfaces, statistical process control, and open factory-network communications.

Obviously, open standards play a major role in our view of the future. The emergence of de facto standards that gain the broad support of multiple vendors is vital to creating an environment that allows this vision to emerge.

IBM-PC compatible architecture will drive the future of motion-control systems. And a single controller will handle more and more functions.

ORMEC Systems President and CEO Gordon Presher, Jr.: After receiving a EE degree from the University of Rochester, Presher served as a project engineer at Eastman Kodak. He founded ORMEC in 1982.

Where engineering meets medicine

Where engineering meets medicine

Warsaw, IN--What do Pope John Paul II, Elizabeth Taylor, and Liza Minnelli have in common?

Like tens of thousands of people worldwide, they enjoy a more active and pain-free lifestyle, thanks to hip implants designed by engineers at DePuy, Inc., which this year celebrates its 100th anniversary.

DePuy, along with two rival companies--Zimmer and Biomet--account for 40% of all the artificial joints manufactured worldwide, making this unassuming North Central Indiana town of 12,000 the "orthopedic capital of the world."

Splints to implants. It all started a century ago when Revra DePuy began making wire mesh splints to replace the wooden barrel staves commonly used for fractures. Now DePuy's annual sales total $680 million. From 1985 through 1994, the company grew at a compounded annual rate of 20%. Long the leader in hip implants, Depuy has broadened its scope to include implants for knees, shoulders, and other joints, as well as surgical tools, protective clothing for surgeons, and other medical products.

It also has become a mecca for a special breed of engineers drawn to a field that allows them to push the limits of technology, while at the same time giving people a much better quality of life.

Take Frank Bono, an ex-aerospace engineer with Hughes. Where he once worked on missiles used in the Gulf War, Bono now develops hip implants like the Replicaa, which incorporates many of the core technologies that have made DePuy an industry pacesetter.

Developed over a 20-month period and approved by the FDA in December of 1994, the Replica marries several materials technologies. It is constructed mainly of cobalt chrome alloy, machined in a 42-step process to meet tolerances as tight as 1/1000 of an inch. A round ceramic head fits over the top section of the implant. This ball-like head in turn fits into a cobalt chrome alloy socket lined with a wear-resistant grade of polyethylene developed through a partnership with DuPont. The surgeon needs no cement to hold the implant in place; a patented porous metal coating applied to certain sections of the device promotes a natural bonding through the ingrowth of tissue.

A great deal of engineering, including 3D CAD modeling and finite element analysis, goes into shaping the implant to insure structural strength and patient comfort. For example, the bottom or distal section of the implant is fluted to reduce rotational forces as the individual moves about. There's also a slot, cut into the stem of the implant by a wire EDM process, to reduce stiffness in the device and create some natural "give" during movement.

These and other design subtleties develop from close contact with surgeons and others in the medical community. "There's not a single product engineer who hasn't been in the operating room at least a dozen times," says Tony Cutshall, who is in charge of new venture projects. "We always ask ourselves, 'How can I make it easier for the surgeon?' "

Engineers routinely visit with surgeons, listening to their suggestions and answering their questions about both the implants and the surgical instruments that DePuy designs in conjunction with the devices. DePuy engineers often address meetings attended by top orthopedic surgeons from all over the world.

"I think just about every engineer here wanted to be a doctor at some time or other," notes Michael Esch, who develops knee implants. "The work demands engineers who are very people oriented."

DePuy has been manufacturing artificial knees for more than 16 years. Its LCS(R) (low contact stress) total knee system uses a polyethylene bearing material to simulate the movement of the human knee. Here, too, sections of its cobalt chrome alloy components are covered with a porous coating to achieve natural adhesion without the need for cement.

Says Esch: "I've got a picture of a 48-year-old fireman who has the LCS knee, and he's carrying someone out of a building. He's also a referee."

Recipe for success. Engineers at DePuy agree that the field of bioengineering demands broad-based, outgoing engineers who can blend the technical precision demanded in their designs with the individual needs and preferences of surgeons. Most have master's degrees in bioengineering or biomechanics, with undergraduate training in mechanical engineering or materials science.

DePuy engineers also work very closely with marketing to promote and sell the company's broad line of standard products and to customize, where necessary, to meet the special needs of surgeons and patients. For example, the company has developed special proprietary software that can transform readings from a patient's X-ray into a CAD model in minutes--then transfer the data to a CNC machine for actual production of a hip implant.

Most of the product development and design staff use Intergraph TD 30 workstations. They create their 3-D drawings primarily with Intergraph's EMS software. Intergraph's FEA package is used for structural analysis.

And very few companies rely more heavily on stereolithography. The company owns three SLA 250 prototyping machines from 3D Systems. Dan Anderson, who heads the Engineering Services department, says this equipment has cut months from the product development cycle and saved thousands of dollars in tooling costs. It's also given engineers and model builders the time to pursue other projects, such as development of a new shoulder implant system.

The fact that the company is a technological leader and gives its engineers wide freedom to pursue their interests in an "entrepreneurial environment" more than makes up for Warsaw's sleepy small town image, notes Stacey Milionis, a group product development manager who left a job in Los Angeles to join DePuy five years ago. She worked initially in implant development but now heads development of an entirely different product line--Sterile View(R), a complete system for protecting surgeons and other operating personnel from blood-borne viruses. Looking very much like a lightweight space suit, it consists of such items as disposable hood and gown, helmet and face shield, and portable blower and air filter connected to a belt around the doctor's waste.

New horizons. Other ventures to broaden the company's mission include the DePuy DuPont Orthopaedics alliance. It has yielded products ranging from the enhanced Hylamer(R) polyethylene for implants to special surgical glove liners made from Kevlar(R) and Lycra(R) that protect against cuts and punctures.

Longer term, the company is pursuing research projects with several universities. For example, DePuy is working with Purdue University to investigate the use of pig intestines as a biological replacement for damaged human tissue, such as tendons and ligaments. Clinical tests on humans using this small intestine submucosa, or SIS, will begin in 1996, says DePuy Research Director Todd Smith.

For Smith and DePuy's technical staff, developing future generations of implant systems and other medical products will be tougher in this new era of increased government controls and curbs on Medicare reimbursement. "The regulatory environment is now very unfriendly to new product development," says Smith. "And that means that controlling costs have become more important than ever." As a result, development has been slowed on new types of implants that patients need to relieve serious pain in such areas as finger and jaw joints.

While the sky is no longer the limit when it comes to developing new medical devices, most engineers at DePuy wouldn't think of turning away from their speciality. "Surgeons introduce me to patients as the engineer who designed your implant," says Frank Bono. "They smile and tell me how much better they feel. That really makes your day."

Make software easy for engineers to use

Make software easy for engineers to use

Peter was one of the original founders of SDRC in 1967. He has served on the company's board of directors since 1983. Among positions he has held within SDRC are vice president and manager of strategic marketing in the software products division, general manager of computer services, and engineering consultant in the engineering services division. He received his M.S. in physics from the University of Michigan in 1968, and his B.S. in physics from the University of Cincinnati in 1964.

Taking the complexity out of CAD and other software is critical, says SDRC's Peter. In fact, he adds, ease of use will be a product differentiator.

Design News:What are the major trends in CAD today?

Peter: There are several. Hardware advances allow us to do a variety of things we couldn't do before. Among the offshoots will be components for virtual reality. But, we can also improve the way users interact with knowledge-based engineering applications, the way they access data bases, and the advisors we include to guide users. Additionally, we are seeing greater use of standards, and that will continue. There will be a seamless flow from application to application, and the applications from third parties will be seamless. Through all of this, the user interface remains critical. In fact, ease of use is everything, and future products will be differentiated by their ease of use. There is a tiered approach to software that's important to understand. At the top end are the traditional users who are comfortable with Unix. But, at the lower end are potential CAD users who use no software tools now or very simple tools, and they represent a big opportunity for software companies. For them to make the transition to software-based design, ease of use is essential.

Q: What will be the next breakthrough in CAD?

A: It won't be virtual reality. The hardware is too expensive. Knowledge-based engineering may be the next breakthrough. It lets engineers interact the way they think. Many software companies are thinking about incorporating aspects of knowledge-based engineering into their products. We already have. Among examples is a simulation advisor we have in our product. Our graphic user interface has intelligence in it so you can see where you previously made decisions on a part.

Q: What are the most important things for software developers to keep in mind during development of their products?

A: Get users involved in all aspects of design and delivery. In our case, users helped us specify the most recent version of our I-DEAS Master Series and told us how they liked the user interface. Before beta testing, we had several external experts go through the software and try to break it. Toward the end of the beta process, we got 25-30 customers to spend two weeks at our facility and use the software to design and simulate products. We told them to wring out the software. They found things they didn't like. So, we took another two months to improve the product before releasing it. That kind of rigorous routine accomplishes a lot more than simple question-and-answer focus groups can accomplish.

Q: What role will product data management (PDM) play in the design process?

A: First of all, PDM doesn't design anything. Instead, it helps users organize, preserve, and control the production of data. That's important because, especially in large design environments, the amount of data is enormous. Without PDM, CAD won't reach its potential. CAD and other data must be shared and controlled, and that requires data management.

Q: Please briefly describe the most important attributes of your Metaphase data-management product.

A: It is object-oriented in construction and allows for customization. That latter point is particularly important, because it lets customers adapt the system to their own processes. Metaphase is also for enterprise environments. Customers tell us they start small with the product, but over time they want it to handle the entire enterprise.

Q: What are the major demands engineers are making on software companies at this time?

A: They demand seamless flow from application to application, and that requires close cooperation among developers. They are also demanding services. In fact, we've found our integration and implementation services are often key for helping customers re-engineer their processes around software tools. In the last two years, our implementation services have grown ten-fold. In a way, it takes us back to our roots.

It's SHOWTIME!

It's SHOWTIME!

Ask engineers to identify cutting-edge industries in the use of fluid power, and they're likely to name aerospace or factory automation. The truth is that today's most innovative fluid-power applications are taking place in the entertainment industry.

There, fluid power simulates realistic movement in Broadway plays, Hollywood movies, and theme parks. On Broadway, for example, "Phantom of the Opera" and "Sunset Boulevard" use hydraulics to quickly move heavy stage sets. Movies, from "Free Willy" to the soon-to-be-released "Executive Decision," employ hydraulics to pitch and roll a 747, shoot water from a whale's artificial blowhole, and blink a mechanical eyeball. At theme parks, fluid power's role is almost limitless. Universal Studios technicians use it to simulate motion on such rides as "Back To The Future." They also enlist it to power heavy-duty monsters, such as King Kong and the great white shark from "Jaws."

From a technical standpoint, entertainment applications are consistently among the most complex. Most use some measure of proportional control and closed-loop feedback. Many also require high-speed operation. "In entertainment applications, engineers are trying to realistically simulate motion, and that requires very fast response times," notes Ken Buda, vice president of sales and marketing for Parker Hannifin Corp., Cleveland.

Many of the applications also require high force. "Motion bases," or platforms on theme-park rides, often involve tremendous loads. What's more, those loads typically are accelerated at extraordinary rates, and the impact has to be absorbed by the power medium. For that reason, hydraulics have emerged as the system of choice for such applications.

The following examples show why. They were chosen not only for their obvious high-force requirements, but also to demonstrate the combination of advantages afforded by fluid power--speed, power, precision, and quiet operation.

Whatever the requirements, engineers say that such applications head the list of innovative uses of fluid power. As Buda puts it: "In terms of proportional controls, servos, and feedback devices, the entertainment industry is at the cutting edge."

Hydraulics shake, rattle, and roll Boeing 747

Imagine that you've been assigned to move a 75,000-pound structure at peak velocities of eight feet per second. What's more, you've got to accelerate and decelerate it in less than three-quarters of a second in a safe, controlled manner.

How do you do it?

That was the problem facing special effects engineers assigned to the new Warner Brothers film "Executive Decision." The movie, in which a terrorist hijacks a passenger airliner, includes scenes in which a Boeing 747 mock-up is rocked n20 degrees from side to side and nose to tail.

To achieve the special effects, Warner Brothers purchased the interior of a 747 airliner and attached it to a 46-foot-long by 20-foot-wide platform supported by steel beams. To enable the platform to move in two directions, technicians mounted its center on a large pedestal containing a universal joint-style bearing. Total weight of the aircraft interior, steel platform, camera riggings, and 150 live actors seated on board: 75,000 pounds.

To pitch and roll the "plane," engineers from Mayo Hydraulics, Bakersfield, CA, designed a massive, hydraulically powered, closed-loop motion system. A custom-built, 500 hp hydraulic unit powers the motion package. It includes:

Eight Parker Hannifin PAVC100, low-noise, high-efficiency, 3,600-psi variable volume piston pumps.

  • Four Parker 15-gallon nitrogen gas bottles plumbed to a piston accumulator.

  • A fluid conditioning system employing a Parker filter.

  • Four large Parker cylinders to move the platform.

Located 10 feet from the platform's giant universal joint, the cylinders work in harmony to provide the desired motion profile. As they retract and extend to the full length of their 78-inch strokes, the cylinders pitch and roll the platform. Residing 15 feet off the floor, the platform can be tilted as high as 26 feet at one end and as low as 4 feet at the other, depending on the position of the cylinders.

To move the 75,000-pound load, engineers employed two cylinders with 5-inch bore diameters and 3-inch-diameter rods, and two cylinders with 7-inch bore diameters and 4-inch-diameter rods. Operating at 2,500 psi, a single 7-inch cylinder can generate 65,000 pounds-force while retracting.

One of the key technical challenges for engineers was to quickly move the platform's enormous mass. To reach the 8 ft/sec velocities they needed, the engineers supplemented the pump flow with the nitrogen gas bottles and the accumulator to help the motion system attain flow rates of 600 gpm. Visitors to the film site say that the 8 ft/sec movement of the giant platform generates a 747-like whoosh of air throughout the studio.

To control the platform's motion, engineers incorporated a PC-based system. The controller generates a motion profile and communicates that to a Parker BD99 amplifier card. The amplifier card compares the analog signal from "string-pot" potentiometer sensors on the cylinders to the motion profile command. It then sends a signal to two 482 gpm Parker D111FH proportional directional valves, which control the velocity and the position of the actuator.

By using the hydraulic control system, Mayo and Parker engineers enabled the movie's director to choreograph the motion to his liking. It also enabled him to replay the sequence of movements as many times as necessary to obtain the desired film footage for a given scene.

Engineers say that the magnitude of the project eliminated alternative types of motion systems. "With electrics you couldn't achieve the speeds or forces that were required," notes John Rothas of Mayo Hydraulics. "For this kind of application, it absolutely had to be hydraulics."

Fluid power shines on 'Sunset Boulevard' stage

When Norma Desmond, the tragic heroine of Andrew Lloyd Webber's hit musical "Sunset Boulevard," is lowered onto the stage on a 37,000-pound set, the audience at New York's Minskoff Theater never hears the whine of a hydraulic pump. Nor do they hear the hum of a cooling fan.

The reason Norma sings without the accompaniment of machine noise is that the movement of the set is controlled by a hydraulic system designed specifically for quiet operation. The heart of the system consists of an integrated motor-pump that dramatically reduces noise. The secret: it has no cooling fan.

During the play, the motor-pump acts in conjunction with a steel-cabled winch system to lower the set into place. The winch's cables connect to a hydraulic brake, digitally regulated by proportional control valves. A microprocessor-based controller, made by Feller Precision Inc., Tappan, NY, regulates the hydraulic system.

Quiet pump the solution. Key to the system: a 30 hp IMP 22 Integrated Motor Pump with a PVH 74 piston pump running at 1,300 psi. The unit, manufactured by Vickers, Inc., Maumee, OH, can deliver flow rates up to 33 gpm at 1,000 psi. Vickers engineers claim that the 33 gpm motor-pump is so quiet that it operates with less noise than a 3 gpm oil recirculation pump that runs adjacent to it.

Although previous productions of "Sunset Boulevard" have solved the noise problem, they have done so at considerably more expense, says Dan Hoffman, president of Birchstreet Design, the system's designer. In the show's West Coast version, Hoffman used a separate pump and motor, which was cooled by a fan. The hydraulic equipment, contained in a basement room at Los Angeles' Schubert Theater, was housed in a soundproofed acoustical enclosure. The enclosure retained the heat generated by the pump and motor and, as a result, had to be air conditioned.

In contrast, the Vickers Integrated Motor Pump doesn't require a fan. Instead, cooling is provided by oil flowing through the motor and into the pump. This enables the motor and pump to be enclosed within a shroud, reducing the noise level even further. Overall, Vickers engineers say their unit runs about 3.5 times quieter than a conventional motor and pump combination.

Because of the integrated design, the new motor-pump also reduces the potential for leaks. Oil flows at low velocity (roughly 2 ft/sec) and at low turbulence as it travels to the center of the pump. The oil absorbs heat by circulating through the bearings and around the rotor, stator poles, and windings before flowing into the pump.

Moreover, the new system is 30 to 45% smaller than a conventional system, yet it still produces the same pressures and flow rates. Because oil absorbs heat more effectively than air, the smaller motor can operate at greater speeds and torque levels.

By using the Integrated Motor Pump, the system needed no extra sound-proofing or air conditioning. This reportedly saved the producer of the show $6,000 when compared to the cost of installing a conventional hydraulic system.

Zoo hydraulics make elephant's trunk more user friendly

Engineers typically cite high force as a prime reason for selecting hydraulics as a power medium. Often forgotten is the fact that hydraulics can offer pinpoint control and luxurious feel for low cost.

That was the case for a design team at the Tulsa (OK) Zoo in the construction of a joystick-based "edu-tainment" system. Located in the zoo's pachyderm house, the system electrohydraulically simulates movement of an elephant's prehensile trunk. Modeled after the Indian elephant, the cloth skin replica even mimics the movement of the elephant's "finger" at the end of the trunk.

Children operate the trunk with joysticks that tip it, move it up and down, or slide it left and right. A single-axis joystick provides up-down and left-right movement. A dual-axis joystick controls trunk tip and finger movement.

To accomplish all that, the trunk uses cable-and-pulley systems mounted over flexible leaf springs. Four hydraulic cylinders apply tension to each of four cables. An electrohydraulic valve stack, made by Apitech, Butler, WI, meters flow to each of the four cylinders. Two Apitech MJ Series electric joysticks command the Apitech VPL Series electrohydraulic proportional valve assembly. An electric motor, a 15 gpm hydraulic pump, and a reservoir provide power to move the trunk.

Valves the key. The VPL electrohydraulic proportional valves form the heart of the system. They offer pressure-compensated flow that enables each of the four cylinders to operate independently. Pressure compensation alleviates potential problems that can occur when one channel in the valve assembly operates at different pressures and flow rates than another channel. Without it, a pressure increase to one cylinder could result in the same increase to a neighboring cylinder.

To prevent that, the VPL valve employs a reducing valve scheme. This enables the valve to maintain a constant pressure drop across the main metering element.

In the elephant-trunk application, the valve results in a more consistent feel for the operator. "The feel of each function is independent of the operation of the other functions," notes Scott Nagro, southeast regional manager for Apitech. "This way, we maintain the integrity of each function."

The system's designers claim they could have used an electro-mechanical system to power the trunk, but not at the same cost. They estimate that one servomotor-driven axis would have cost the same as all three hydraulically driven axes. "The open-loop, load-sensing hydraulic system is more energy efficient and cost effective for this application's duty cycle than electrics or pneumatics," adds Robert Cook, special projects designer for the zoo.

The pachyderm application aptly reflects the advantages of hydraulically powered motion, Nagro contends. "This isn't a case of the brute force advantage of hydraulics," he says. "It's a matter of hydraulics offering a less expensive, more user-friendly package."

trueSpace2

trueSpace2

trueSpace2 3-D illustration package offers an arsenal of modeling and rendering tools that will bring out your industrial designer or video producer talents to enhance your technical CAD drawings.

Setup & interface. In the trueSpace2 interface, tools are primarily grouped by function and are allowed to float on the screen. You can place the main menu at the bottom or top of the screen and customize it with groups of tools for editing, modeling, or rendering. These groups are actually pop-up icons that, once clicked, reveal extensions of the main tool. Click on a 'sub' icon and it becomes the default tool of that group.

From an engineer's standpoint, you would expect trueSpace2 to be loaded with 2-D drawing features. Unfortunately, its 2-D geometry tools are sparse. Your other option is to import completed objects as DXF, Postscript (PS), or Encapsulated PS and let trueSpace2 show its true strength in 3-D.

The constructive screen is shown as a 2-D grid in space with 2 or 3 default light sources. With this setup it is rather difficult to orient objects in space, since a global coordinate axis system is not present. Instead, every 3-D object has its own coordinate system which can be displayed. Since there is no way to display coordinates as you move objects around, you have to rely on the object's information display which acts as the snap control.

3-D tools. You can begin to build 3-D objects either from your 2-D objects or from the supplied 3-D primitives. 2-D entities can be extruded, swept, or revolved. Once you start combining these objects, trueSpace2's Boolean operations help you intersect or join them, or subtract one from another. But trueSpace2's 3-D arsenal goes one step further. The Deform object tool allows you to take any object, change it, and create what is called an organic object. Unfortunately, the lack of snap control makes it difficult to join objects at say, a common surface. The object information menu is one resource for matching entities, though on a point-by-point basis only. The other option is to use the dimension tool, which updates every dimension on the object itself, as you move points around.

Text capabilities are limited to simple text in any True type font. The text is treated like any object that can be extruded or manipulated. The only downside is trueSpace2's inability to edit the text once it becomes part of the scene.

The multiple view option opens many windows so you can see the scene from any viewpoint. Keep the main window as the constructive, and you can render in another with all the changes you make reflected on any other open window. Using Intel's 3DR API, you can test the sensitivity of lights and material at a much faster speed. Crisp outputs in trueSpace2 are achieved with hardware featuring 8,000 by 8,000 pixels and 32-bit color depth.

Animation. When creating animation sequences, objects on the screen can be placed anywhere and a time sequence can be constructed using the Visual time editor. The animated sequence can be made in a straight-line fashion, or you can customize the path the objects will follow from frame to frame. For applications where certain portions of the model move, trueSpace2 allows you to record motion by disassociating portions of the model. You can also use the Deform tool capabilities to record sequences depicting objects going over or through other ones.

I think trueSpace2 is among the top notch software in the 3-D modeling and rendering market. For engineers who need more definition than art, trueSpace2 can be the artistic extension to their work rather than one of their core tools.


SPEC BOX

trueSpace2

Minimum (recommended) hardware: An 80386/25 (486/DX2, Pentium) with 8 (16)M bytes RAM, Windows 3.1 with 8 (24)-bit video, 8 (16)M bytes hard disk space, and 640x480 (800x600) 8-bit color.

List Price: $795

Caligari Corp., 1933 Landings Dr., Mountain View, CA 94043; ph: (415) 390-9600.


A similar product:

Ray Dream Designer - Ray Dream Inc., 1804 N. Shoreline Blvd., Mountain View, CA 94043; ph: (800) 846-0111.

Application Digest

Application Digest

Know when to select a servo system

Ed Steiner, President, Industrial Indexing Systems

Accurate, efficient production machines often require flexible motion control systems to meet performance goals. Choices include a simple variable-speed drive, low-cost stepper motors, or a full closed-loop servo system.

A servo system is the best choice if the motion trajectory exhibits any of these characteristics:

Smooth, slow-speed movement.

  • Precise speed control, less than 1% ripple.

  • High repetition of start-stop motions.

  • Full torque at zero speed.

Certain load characteristics indicate need for a servo system:

  • Changing inertia or friction loads.

  • Unpredictable load changes.

  • Need to reverse direction without delay.

In addition to these guidelines, servo systems are especially suitable for specific control requirements. For example, those applications where the controller must know when load stalls, or moves outside the desired trajectory, benefit from a closed-loop servo system. So do situations calling for multi-axis control with closely coordinated motion or anti-collision requirements.

Engineers should also examine how the load interacts with the servo system. Finally, supplier selection is as improtant as the system itself. Choose a vendor with demonstrated experience--one that wants to be a partner, not just a supplier.

To speak with an applications engineer from Industrial Indexing Systems, call (716) 924-9181 or FAX (716) 924-2169.


Improve gasket design with wise material choice

Geoff King, Product Manager, Norton Performance Plastics Corp.

Today's engineers are no longer confined to EPDM, neoprene, and butyl when choosing materials for electronic enclosure gaskets.

One material to consider: foam. It uses less material than a solid, weighs less, and handles better during installation. It also remains more supple over time and recovers better after compression.

Three foamed polymers or elastomers are another attractive option for electronic enclosures: PVC, thermoplastic rubber, and rubber-modified polyester.

It also makes a difference to the enclosure design engineer how the foam was produced. Cast-and-slit foam sealants are made like a big roll of carpet, then slit into widths or die cut to order. Thus, the top and bottom surfaces are smooth, but sides expose cut cells.

Extruded dry foam adds some design benefits to a gasket. Custom cross sections are possible, which can lead to more effective and economical designs. And, the entire exterior has a continuous skin.

When a permanent seal is required, butyl-coated PVC foam is an excellent choice. The joint has all the advantages of butyl: tenacious adhesion, low moisture and vapor transmission, and excellent aging properties. Yet, the core has all the desirable qualities of a flexible closed-cell foam.

Within the last few years, a new breed of foam-in-place gasketing has captured a lot of attention. Called Dynafoam(R), it goes on and sets up as readily as a thermoplastic. The material is a one-part, moisture-curing, rubber-modified polyester. Gaskets as large as 0.75 inch in cross-section have been produced in a single pass.

To speak with a Norton applications engineer, call (518) 642-2200.

Engineering News

Engineering News

Aircraft designers look to 'wired wings'

What would automobile travel cost if cars needed ten man-hours of maintenance for every hour of driving? It's not really a fair comparison to the figures for flying--a breakdown on the road isn't as worrisome as one aloft--but the heavy maintenance needs of conventional aircraft present a crushing economic burden on military and civilian flight.

Engineers grappling with aircraft maintenance difficulties have targeted hydraulic systems as especially troublesome. Although hydraulic systems' power-to-weight ratios still reign supreme, sources say that advanced power-switching electronics and electric motors may soon supplant hydraulics in aircraft flight-surface-control and utility applications.

The potential benefits from a change to electric actuators on aircraft? "Reliability, maintainability, supportability, and lower life-cycle cost," answers James Cloyd of the Air Force's Wright Lab- oratory. Advances in electronic components should give electric actuators greater mean-time-between-failure than hydraulic designs. Self-contained electric actuators would be line-replaceable units. Eliminating hydraulics reduces the need for specialized ground-support equipment and personnel. And, an electrically operated aircraft would have a shorter logistics "tail:" that is, fewer fluids, solvents, and lubricants; and fewer environmentally hazardous spills to clean up.

What this means to you
  • Electronics may replace hydraulics in aircraft and elsewhere

  • Lighter, more-reliable, and more-easily repaired aircraft designs.

Cloyd serves as chairman of the U.S. government's More-Electric Aircraft initiative, a series of R&D programs looking into electrifying every aspect of aircraft power requirements. "The strategy is to demonstrate technology on existing aircraft to solve real problems today," he says, "as well as to encourage spinoff of technologies to a variety of other industries." Finding answers to power-delivery problems should create demand in commercial aerospace, manufacturing, and electric-vehicle industries that will eventually drive down the cost of electronic components for military aircraft.

Work on electric actuators and power supplies has been going on for more than ten years. Prototypes flew in the mid '80s on an Air Force C-141, the so-called High-Technology Test Bed C-130 in 1990, and the Electrically Powered Actuator Design Validation F/A-18 in 1993.

Development centers on two types: electromechanical actuators (EMA) and electrohydrostatic actuators (EHA). Curiously, it's the EHA design, where an electric motor powers a self-contained, fixed-displacement hydraulic pump and actuator, that seems to have the upper hand. The reason concerns reliability.

In the event of a malfunction, "an EHA can be by-passed and returned to a previous position," explains Jim Ryder of Parker Bertea's Control Systems Div., Irvine, CA. "The jamming solution requirement hasn't been overcome in the EMA. I don't know of any solution that's acceptable to the prime contractors, the government, or the FAA."

Design work continues because hybrid electrohydrostatic actuators raise unique concerns of their own. "One of the technical challenges is having to dissipate a lot of heat," explains Scot Schaefer, director of Moog, Inc.'s technology center in East Aurora, NY. The relatively large fluid volumes of conventional hydraulic systems serve as an effective heat sink. But an EHA and its power supply require auxiliary heat-transfer apparatus that adds to their weight and partly negates the weight savings electric-actuation proponents count on.

Other issues, like leaks from the EHA's reduced hydraulic reservoir, lower power-to-weight, and longer response times, seem less of a concern. Parker's Ryder points to improved, redundant seals and the simplified replacement of self-contained units. And Moog's Schaefer feels that dealing with EHA's dynamics will become easier with experience. Those problems may pale beside the overall benefits of replacing an airplane's central hydraulic system. "The savings are in the plumbing, not the actuators," says Schaefer.

Cloyd agrees. The More-Electric Aircraft (MEA) initiative's Joint Planning Team has identified four technologies vital to changing the way aircraft look, fly, and are maintained: a starter/generator integrated within a turbine engine to eliminate geartrains and permit the use of magnetic bearings (see Design News, 3-28-94, p.40); electric primary flight-control actuators; an integrated auxiliary power unit with battery or compressed-air start; and a fault-tolerant power management, distribution, and motor-control system. Plans call for a first-generation MEA to fly in 1998 and a second-generation aircraft, with the embedded generator and distributed power and control systems, by 2008.

Aircraft designed along the lines of MEA would be slimmer, faster, and have longer range. "In the long term, MEA would be almost autonomous in the logistics sense," says Cloyd. For civilian aircraft, these benefits would translate into lower ownership costs. For the military, easily deployable, more-reliable aircraft allow getting more done with fewer resources. That's a goal worth pursuing, because, as he explains, "We know there will be manpower reductions, but our job of defending the nation won't go away."

Recent advances in high-temperature power electronics bolster prospects for more-electric aircraft. This silicon-carbide-based op amp withstands temperatures to 500 degrees C.

Achieving the weight and cost savings envisioned for the Air Force's More-Electric Aircraft requires a near-complete elimination of fluid power in the aircraft.

Moog, Inc. developed this triplex redundancy-management scheme for tandem-pump EHAs. Third, or model, controller channel arbitrates disagreements between other channels.

Parker Bertea's self-contained electrohydrostatic actuator reflects 10 years of design work. Note the extensive heat sinking around the high-pressure reservoir.

--Terrence P. Lynch, Northeast Technical Editor


Bearing maker cleans up cleaning process

Peterborough, NH--New Hampshire Ball Bearings (NHBB), Inc. has installed a new process that allows it to satisfy ongoing requirements for contamination-free parts, while also meeting stringent environmental standards.

The non-ozone-depleting (NOD) process removes oils and particulate matter from its high-precision ball and roller bearing assemblies. NHBB customers require the ultra-precise components for such applications as aircraft engines and airframes, medical devices, machine tools, and computer components.

NHBB weighed several options before settling on the Advanced Vapor Degreasing (AVD(TM)) process. The first option considered to replace the 1,1,1,trich-loroethane and chlorofluorocarbon (CFC) compounds used in the cleaning process involved water-based cleaning. While it seemed appropriate for certain bearing components, completely assembled bearings proved incompatible with the process. Water droplets deposited by the aqueous cleaning could trap contaminants, displace lubricants, and degrade bearing performance.

Semi-aqueous cleaning of assembled bearings also was investigated. However, the alcohol dewatering agents raised added safety concerns and were rejected.

The non-aqueous AVD cleaning method, developed by Petroferm, Inc. in cooperation with 3M, uses non-ozone-depleting cleaning and rinsing agents to remove the oil and particulates. The process employs a two-sump, batch-cleaning system and two liquids, a solvating agent and a rinsing agent. Cleaning with AVD involves immersing the parts in a boil sump containing the two agents.

After a boil cycle of about two minutes, the parts basket is transferred to the adjacent rinsing sump. Here, the rinsing agent displaces both the solvating agent and its dissolved oily contaminants. The lower-density, contaminated solvating agent quickly rises to the surface of the rinse sump, where it is carried back to the wash sump as overflow.

Non-ozone-depleting process allows New Hampshire Ball Bearings to clean its high-performance parts without any fear of residual contamination.


Color concentrates give Brother a competitive edge

Bartlett, TN--For years, Brother Industries, U.S.A., Inc. relied solely on outside molders to process its business-machine components, primarily using pre-colored HIPS and ABS resins. But with growing competition, Brother determined that it was vital to lower resin costs.

Therefore, in the early 1990s, Brother began exploring the option of using natural-base resins, plus concentrates, as an alternative to pre-colored resins. To help bring this about, the company initiated a process of tight-tolerance color matching and sampling. Experience gained at these trials showed that concentrates not only exhibited excellent color capabilities, but were more efficient to inventory and less expensive than the pre-color alternative.

The results contributed to Brother's decision to invest more than $3 million to build a large molding operation, complete with four injection-molding machines, silos, cooling towers, and state-of-the-art color-blending equipment. In August 1992, the company began its own molding operation--with a reduced reliance on outside molders. Then, in the fall of 1992, it switched all of its molders of HIPS-HB-grade polystyrene to natural, with the concentrate supplied by ReedSpectrum, Holden, MA. The next year, Brother shifted its ABS coloring to concentrates as well.

Benefits derived from the natural concentrate formula:

Base resin-material costs went down due to an increase in purchasing power for one resin, plus concentrate, vs. the high cost of purchasing numerous pre-colored, same-base resins.

  • Overall inventory costs decreased as only a couple of base resins, plus the concentrate, required storage--base resins would not become obsolete.

  • Lot-to-lot consistency improved because all molders used the same natural resin, plus concentrate, all of which have tight color tolerance for every color lot.

Brother's Kirby model word processors benefit from the use of color concentrates for many of their key components.


Insulated powders boost motor efficiency

Emporium, PA--Engineers at Pennsylvania Pressed Metals (PPM), Inc. are replacing laminated steel with insulated iron powders. In electromagnetic applications where constant magnetic permeability and low core losses are required, engineers say, Ancorsteel(R) Insulated Powders (IP) from Hoeganaes Corp., Riverton, NJ, can reduce cost and improve efficiency.

The powders use a non-conductive thermoplastic polymer coating that makes them suitable for ac applications, according to William Michael, Hoeganaes sales and marketing vice president. For example, PPM engineers recently replaced a low-carbon steel positioning grid with SC-120, which offers the best permeability of the Ancorsteel line of powders.

The grid provides a magnetic path for a positioning motor in a panel printer. Its complex geometry made laminated steel an impractical choice, explains materials and process development manager Ryan Sun. "It's a fairly large part, and the concern was that heat build-up would reduce the motor's efficiency," says Sun.

Although the grid was converted to IP from machined cold-drawn steel for cost savings, the new design also improves efficiency and provides low eddy current loss, says Sun.

IP also is improving the housing of a small electric motor. Machining the tube-shaped housing from bar stock laminated steel would be prohibitively expensive, Sun says. Instead, engineers chose Ancorsteel TC-80, which offers the lowest core losses of the IP series.

After molding, the part is thermal-treated and secondary machined. The part's final density is 7.0 -7.2 g/cm 3. The design improves the motor's efficiency, and allows engineers to create several parts and assemble them to make a longer housing, adds Sun.

Powders treated with a non-conductive coating yield insulated parts such as this housing for a small electric motor.


Data exchange gets products moving

Kitchener, Ontario--For Apex Metals of Kitchener, Ontario, designing small- to medium-sized stampings for companies like Ford, Chrysler, Honda, and Toyota is no easy task. To ensure precise control over their designs, Apex engineers use CATIA 3-D CAD software.

The main benefit of a 3-D environment, says Harry Tempelman, engineering CAD-CAM supervisor at Apex, is that a designer always knows exactly where he or she is in space. "It is much more difficult to visualize a design when it's flat or in 2-D," he says. "With 3-D we have much more control." Apex runs CATIA on an RS6000 workstation, and has an Electronic Data Interchange set up with some of its customers, including Chrysler.

3-D design has also proven useful when presenting proposed designs, by enabling customers to better visualize how a part will work. In the past, say engineers, this kind of understanding was sometimes only possible after a part was already manufactured.

When making 3-D presentations in the customer's location, Apex avoids tying up a CATIA workstation on site by bringing along a portable PC. Originally, moving CATIA files to this PC was difficult because of severe limitations on sending CATIA files to a printer or other output device. Tempelman solved the problem with CadDesign, a file-conversion package from Tailor Made Software, Kent, WA.

CadDesign moves CATIA files from the AIX operating-system environment to a TIFF or GIF format. By adding CadDesign to the computer set-up, Apex can now move CATIA files to an IBM 700C PC for in-person meetings, or send a digital file to a customer site where it is loaded into that company's DOS system.

When designing this automotive gear shift lever for Chrysler, engineers at Apex Metals used CadDesign software to translate the 3-D model from a CATIA file to a format useable on PC platforms.


MEs, EEs design in harmony at Peavey

Meridian, MS--Engineers at Peavey Electronics are applying modern computer technology to bring speed and efficiency to an ancient art: designing musical instruments.

"We're in an incredibly competitive and fast-moving market," says spokesman Jere Hess. "We introduce more than 100 new products every year, and many have a life-cycle of six months or less."

CATIA software, developed by Dassault Systemes and sold by IBM, helps engineers simulate parts on screen, do interference checks, and determine inertial and mechanical constraints. And, by doing "virtual prototypes," Peavey engi neers have cut up to two months off their development time. "Now, we do one or two engineering prototypes, and we're done," says Drew Goodman, mechanical engineering supervisor. Before using solid-modeling software, engineers needed an average of six physical prototypes--each taking two weeks.

CAD is also helping mechanical and electronic engineers at the company to work together concurrently on a project--and remain in synch. For example, while the mechanical design team creates a physical box for speakers, amps, and other products; an electronic design team creates circuit boards to go inside. Electronics engineers share their 3-D files from a specialized program with the mechanical engineers. The files are imported into CATIA, providing basic "footprint" information about the number of circuit boards in a product and their size, as well as mechanical components. This ensures that the finished "box" will leave adequate room for the electronics, and allows the EEs to do most of their complex designs while the MEs complete their housing design.

"This is no small accomplishment," Goodman says. "Our circuit boards have to be housed properly, with just enough clearance and elements such as input/output jacks lined up precisely. If we had to take hard-copy line drawings and recreate them in our CAD program, we couldn't be sure of this."


GE Fanuc, Microsoft aim to simplify 'mass customization'

Redmond, WA--A new line of factory automation software from GE Fanuc (Charlottesville, VA) may help design engineers address the increasing demand for "mass-customized" goods. Called CIMPLICITY(R) Monitoring and Control Products, the programs are "the industry's first and most powerful line of factory-automation software products designed for and fully compatible with Windows 95 and Windows NT technology," claims Bob Collins, CEO of GE Fanuc.

The CIMPLICITY line consists of four products: MES/SCADA, MMI, Control, and Motion. They handle everything from enterprise-wide process monitoring and supervision to motion control.

"CIMPLICITY Windows-based tools can automatically integrate the configuration and programming of all automation equipment on the factory floor," says Collins. "Cycle times for product changeovers can be shortened from months to days."

The greatest benefit these products offer design engineers may prove to be in mass-customization. This involves manufacturing a wide variety of products in small quantities but large overall volume, to meet increasing customer demands for unique products. And while computerization of the engineering department has simplified the task of creating mass-customized designs, manufacturing departments have found themselves hampered by the limits of incompatible and difficult-to-use factory-automation systems.

Engineers, comfortable with the look and feel of Windows programs on their home and office desktops, pushed for the same benefits in the shop, both companies say. "We expect such industrial solutions to grow to a billion-dollar business in the next two years," says Pieter Knook, Microsoft's general manager for enterprise solutions.

--Mark A. Gottschalk, Western Technical Editor


Gesture-recognition system may give CAD a hand

Palo Alto, CA--Virtual Technologies Inc. has designed a gesture-recognition system that could pave the way for CAD users to rotate on-screen computer objects with hand motions in the air.

Called GesturePlus, the device is built around a standard PC running DOS. It connects to a data-input device, such as the company's own CyberGlove, and via serial port to a software application. By using a complex series of algorithms, the system takes data input from the glove and determines what gesture has been made.

Users must first "train" the GesturePlus system to recognize various gestures. For example, touching three fingers together could be "pick," and a 180-degree turn of the hand could be "rotate." The user decides on the gestures desired for varoious commands, and inputs them into the system. Once that information is stored, it can then be used in an application set up to support GesturePlus.

R&D engineer Sidney Fels says GesturePlus makes it easier for software developers to incorporate gesture recognition in mainstream CAD applications. Using just the CyberGlove, software developers had to write their own recognition algorithms. "This is the next step to free up the application programmer from having to understand the data," he explains. Virtual Technologies has developed a prototype CAD demonstration which uses the GesturePlus and CyberGlove systems to "understand" a user's hand movements. Company officials hope that commercial CAD software will adopt the technology as well.

GesturePlus is scheduled to begin shipping in November at $3,500 through the end of the year.

GesturePlus, a 'virtual device,' interprets gesture data coming from a variety of sensing devices such as a data glove. The system transmits the name of a recognized gesture, such as 'rotate,' to a host computer. CyberServer hardware allows a host computer to communicate with numerous devices over a single high-bandwidth communication channel.


Software saves John Deere nearly $500K/year

Waterloo, IA--Engineers at John Deere Engine Works say that Design of Experiments software (DOE) has saved them nearly half a million dollars annually by helping them recognize the need to eliminate chromate conversion from their aluminum parts. The software revealed that the expensive additive is not a significant factor in paint adhesion.

DOE is an approach to experimentation that considers all variables simultaneously. It shows how interconnected variables respond over a wide range of values, without requiring all values to be directly tested.

To carry out their testing, John Deere Engine Works chose Design-Ease(R) software from Stat-Ease Inc., Minneapolis, MN, as their DOE approach. "Design-Ease offers the capability to show engineers real-world results," says Supply Management Engineer Wayne Mills. "It helps us understand what's happening without spending days trying to understand the mathematical theory.'

DOE allowed them to test 12 variables in a week, compared with traditional methods that would have tested only five variables in two weeks. John Deere soon narrowed variables down to three: chromate conversion, paint type, and surface treatment. A 3-D cube plot generated by the software showed how the three variables interacted, proving that paint type is the major factor in paint adhesion.

Mills feels that the greatest benefit of DOE is design optimization. "We can design the parts better, at lower cost, and faster using Design-Ease up front during design and development, rather than discovering we have a problem when the part is already out in the field."


Composite aids appearance and assembly speed

Stamford, CT--Good looks were only part of the equation when engineers needed to select a material for the paper-feed deck of the new Pitney Bowes Midrange mailing machines. The part also had to have high strength and stiffness. Designers found the right combination in a glass-fiber-reinforced polycarbonate composite with an internal lubricant.

"The deck is where you place a letter or package to feed it into the machine," explains Bob Reid, a technical advisor at Pitney Bowes. "It's a part that should be pleasing to the eye."

Reid got that ingredient in Lubricomp(R) DFL with a PTFE lubricant from LNP Engineering Plastics, Exton, PA. "The composite certainly provides an excellent surface finish," Reid adds. "However, it's the underside of the deck, the part that you don't see, where the material really makes the difference."

The underside supports much of the machine's internal components. "It's actually a housing for complex parts, such as rollers, gears, and motor mounts," he explains. "The PTFE lubricant and glass-fiber reinforcement of the DFL material yield the low-wear friction, strength, and stiffness needed to support the large number of bearings, tabs, and sliders in the deck."

The material's mold-flow technology also yields a complex-part geometry that fills out completely. "Previously, when we used metal for the decks, we'd take a piece of sheet metal, make individual parts, and then spot weld them together," Reid adds. "Now that we use a plastic composite, we can mold all of these parts into a single unit."


BASF backs education foundation

Mount Olive, NJ--With a $10,000 donation, BASF Corp. becomes the latest addition to the list of top companies supporting the non-profit Design News Engineering Education Foundation. The money will help fund scholarships to the engineering schools chosen by the recipients of the Design News Engineering Achievement Awards.

"The foundation of BASF's success in meeting the needs of our customers is a commitment to technical excellence," says Dr. Reinhard Katz, vice president, BASF Plastic Materials. "The awards program is a part of BASF's education effort, which also includes partnering with OEMs."

With worldwide headquarters in Germany, BASF produces a broad line of engineering materials, including acetal copolymers, nylons, PBT thermoplastic polyesters, styrenic copolymers, several high-performance thermoplastics, high-density polyethylene, and polyurethane automotive suspension products.

Among the key application areas for these materials are: automotive, electrical/electronic, medical equipment, sports equipment, and packaging.

As BASF sees it, technological advancement in materials continues to move very quickly. So, OEMs today must rely on their suppliers for technical support. "It is extremely difficult, if not impossible, for OEMs to be experts on every technology that exists," says Katz. BASF supports engineers through their plastics applications centers in Wyandotte, MI; Germany; England; Spain; Japan; and Australia.

These centers are equipped with the latest computer modeling and analysis tools and can simulate processsing conditions to point out potential trouble spots with designs before tooling begins. BASF plastics processing facilities enable customers to evaluate molds and prototype parts. The customer design and processing seminars cover all elements of application development, including material selection, part design, computer-based flow and structural part analyses, and part and process optimization.

With partnering as a basic way of life at BASF, Katz finds that an optimum combination of state-of-the-art technologies from around the world are used to develop new products. The results: reduced development time and easier development.

For example, the Cadillac's Northstar(R) engine is the first air intake manifold for a V-8 engine to be made in North America using the melt-core injection molding technique. A key strength brought by BASF to this project is its long history of helping automotive companies successfully develop air intake manifolds.


Truck firm turns to stainless-clad aluminum for longer-lasting bumpers

Chicago--Navistar International has become the first major truck manufacturer to offer stainless-clad aluminum as a bright bumper material option on its aerodynamic International(R) class 8 models. The company chose the material over chrome-plated aluminum because of its "proven reputation for appearance, durability, long-term corrosion resistance, and environmental friendliness."

Texas Instruments, Engineered Materials, Attleboro, MA, developed the bumpers. In earlier tests conducted by Robert Baboian, TI principal fellow, the material withstood rough, long-range trucking conditions for up to 1 million miles without losing its bright appearance. The stainless surface does not rust, peel, or spall, even when hit by stones and other scrapes trucks encounter in heavy-duty service. The bumpers, according to Baboian, have survived severe bend damage and repair without corrosion. And they are anywhere from 30-40% lighter than the chrome-plated counterparts, he adds.

Texas Instruments attributes the improved durability to a 0.004-inch-thick surface layer of stainless steel clad to aluminum. The metal bond is at the atomic level, making the materials inseparable. By comparison, nickel-chrome plate on conventional bright aluminum bumpers measures less than 0.002 inch, resulting in a weaker plating bond.

Texas Instruments achieves the bond using a refined process based on solid-state welding technology. The bonding is so effective, says Baboian, that there is no need for intermediate brazing alloys or adhesives.

Virtually any combination of ductile metals can be clad, with individual components representing from 2% to 98% of the total composite thickness. As a rule of thumb, composite properties, such as tensile strength and conductivity, can be estimated as the arithmetic sum of the volume percent of each component times its specific property value. Dimensions of TI clad metals range from 0.001 to 0.150 inch thick, and up to 24 inch wide.

In switching to the stainless-clad aluminum, Navistar engineers stress that the steel-clad bumpers are not more expensive than the chrome-plated version. The switch also enabled Navistar to eliminate shipping and handling costs associated with sending the part to platers several hundred miles away for processing. And, as an added side benefit, eliminating the plating operation made only one supplier fully accountable for the bumper's production.

Stainless-clad aluminum bumpers give aerodynamically designed Navistar International trucks protection from corrosion and other damage.

Molded thermoset composite replaces cast iron

Molded thermoset composite replaces cast iron

Garner, NC-A cast-iron bracket supports the third rail of several electrified rail lines. Bolted to an extended railroad tie, the bracket supports an insulator, which in turn supports the contact rail.

Metro-North Commuter Rail Road is the second most densely travelled passenger rail line in the U.S. The company experienced failure of some of their cast iron brackets in the Park Avenue tunnel. Engineers traced the cause to salty water from the street above corroding the brackets. They also suspected the cast iron brackets of undesirable and possibly dangerous current leakage, even though--theoretically--they are not in the electromagnetic circuit.

As an alternative to cast iron, Penn Compression Moulding adapted composite molding compound technology to produce support brackets. Identical mounting dimensions make the composite brackets direct replacements for cast iron. The material is a glass reinforced vinyl ester thermoset composite. In addition to the necessary structural strength and corrosion resistance, it supplies extra insulation not provided by the cast iron.

Two types of physical tests compared the strength characteristics of the cast iron and composite brackets. In one, a hydraulic cylinder applied a lateral force to failure. In the other, a falling weight supplied an impact force in the same lateral direction. When engineers apply force slowly, the cast iron exhibits higher strength values. In the impact mode, however, the composite brackets absorb more than twice as much energy as the cast iron.

In both cases, the cast iron failed catastrophically with practically no deflection before brittle failure. The composite brackets yield considerably before delamination begins. In addition, the composite brackets do not totally separate from the base. At lower temperatures, the cast iron exhibits lower strength values, while the composite values are higher.

Other Applications
  • Housings

  • Switchgear components

  • Contact rail insulators

"These composite materials really perform in high-corrosion, high-stress environments," says Robert Farrell, corporate engineering manager for Penn. "They provide both electrical and thermal insulation in structural applications."

Composite brackets cost almost 12% more than the cast iron. Self-extinguishing and impervious to the effects of arcing and chemicals, the material is UV-stable. The brackets weigh about one-third less than cast iron brackets. Minimum life expectancy is 25 years.

Additional details...Contact Robert G. Farrell, Penn Compression Moulding, Inc., 1027 Highway 70W, Garner, NC 27529, (919) 779-4474.