Engineering News 7554

DN Staff

May 5, 1997

27 Min Read
Engineering News

Hubble upgrades deliver sharper eye on the universe

Seal Beach, CA--In February, astronauts aboard the Space Shuttle Discovery snuggled their craft up to the Hubble Space Telescope (HST) and spent 33 hours installing some of the most highly engineered mechanisms ever built. They carefully wrestled the phone-booth-sized Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and Space Telescope Imaging Spectrometer (STIS) into place--two instruments that scientists expect will significantly push the envelope of our knowledge of the universe. And they replaced one of HST's three tape recorders with a solid-state recorder (SSR) possessing 10 times the data capacity.

But before the astronauts could install them and astrono-mers use them, engineers spent a decade pushing the envelope on numerous engineering technologies needed to bring the STIS, NICMOS, and SSR to life. "There were people at NASA Goddard who said that this was the most difficult instrument they'd ever asked anyone to build," says Don Hood, technical manager for STIS at Ball Aerospace & Technologies Corp. in Boulder, CO. Ball served as the primary contractor for both the $125 million STIS and the $105 million NICMOS.

Innovations on the three projects include:

  • Dozens of step- and servo-motor motion-control systems that offer repeatable positioning of optical assemblies to as little as 0.20 arc-seconds and linear accuracies of 1 micron.

  • Optics and detectors on STIS with 30 times the spectral capabilities, 500 times the spatial capabilities, and 2.4 times the resolution of previous HST spectrographs. This technology might also have application in high-end digital cameras.

  • Digital detectors on NICMOS that can resolve objects 50 to 100 million times dimmer than can instruments on Earth.

  • Graphite-epoxy trusses that weigh as little as 40 lbs can support peak loads of several tons during launch, yet possess overall coefficients of thermal expansion of nearly zero. These structures could also find use in the Space Station, aircraft design, and terrestrial telescopes.

  • Stacked, high-density DRAM chips and a NASA-developed, radiation-hardened microprocessor on the SSR.

  • Uncountable applications of anti-vibration techniques; outgas-free paints, coatings, and motor lubricants; innovative thermal-management techniques; and redundant everything.

Telescope on ice. NICMOS is the first HST instrument to operate in the 0.8- to 2.5-micron near-infrared region that lets the telescope penetrate the haze of interstellar dust. Scientists hope it will provide answers to questions about star formation, planets in nearby solar systems, and the origin of the universe.

It uses three fixed-magnification cameras, all looking simultaneously at adjacent parts of the sky. Light is imaged on 256x256-pixel HgCdTe detectors. In addition to their IR sensitivity, "these detectors have the advantage over CCDs of being able to perform nondestructive reads," says Paul Lightsey, system engineer at Ball. A selection of filter wheels, polarizers, and grisms (combination grat-ing/prisms) let NICMOS act as telescope, coronograph, polarimeter, and spectrometer.

But undoubtedly its most interesting system is the dewar, an insulated vacuum flask that keeps the detectors at 58K (-355C) to limit thermal noise. The cooling source is a 240-lb composite block of nitrogen solidified around highly porous aluminum foam. The foam was designed to prevent nitrogen chunks from floating around as the material sublimes away over the unit's five-year life.

The dewar is a layered sandwich of insulation and shell casings. Thermoelectric coolers (TEC)--Peltier-junction heat pumps--draw energy away from two layers of the dewar. They conduct heat to external radiators via an assembly of hundreds of thin layers of aluminum foil, each shaped like an "S", that exhibit high thermal conductivity but little structural stiffness.

Supporting the ~815-lb instrument is a 40-lb graphite-epoxy truss that engineers maintained in a nitrogen atmosphere during construction to minimize moisture absorption. "It has a coefficient of thermal expansion of three-tenths of a part per million per degree C," boasts Lightsey. "And it's slightly negative to offset that of the metal components."

Motion-control masterpiece. A two-dimensional imaging spectrograph, the 700-lb STIS contains three detectors sensitive from ultraviolet to near infrared light (115- to 1,000-nm wavelengths). Its spectral and resolving capabilities should enable discoveries of supermassive black holes, solar flares, and the distribution of mass in the universe. "It will give scientists a better insight into what's going on than any spectrographic instrument built before," says Hood.

STIS's pair of 1,024x1,024-pixel Multi-Anode Microchannel Arrays (MAMAs) cover wavelengths from 115 to 310 nm. "Solar blind" to other radiation, the MAMAs don't need shielding from stray sun, moon, or Earth light. They compliment the 1,024x1,024-pixel CCDs that operate from 305 to 1,000 nm. Both two-dimensional detectors gather from 2,048 to 4,086 times the data of previous columnar arrays.

A showcase of precision motion control, STIS is populated by eight mechanisms--two of them three-degree-of-freedom de-vices. Examples:

  • Mode-select mechanism. This uses geared step motors with redundant windings to rotate any of 21 optics into the light path and tilt or tip the beam across the detector. "The mechanism will position the optics and move the beam to the 1- to 5-micron level," says Hood.

  • Slit wheel. It rotates any of 65 restrictive apertures/filters into the beam. A brushless dc torque motor with servo feedback positions repeatedly to less than 10 microns.

  • "Fly swatters." Powered by step motors, these rotate either 90 or 180 degrees to block light from certain optical paths.

  • CCD shutter. A brushless dc torque motor, chosen for its speed uniformity, turns an opaque disk that incorporates precise aperture cutouts.

  • Detector calibration mechanism. This uses a step motor with redundant windings to place tungsten, deuterium, and krypton lamps into the optical beam path.

Like NICMOS, STIS is built on a truss of square- and diamond-shaped graphite-epoxy longerons and tubular members. Proper fiber orientation gives it a coefficient of thermal expansion of nearly zero. "We've limited motion due to thermal changes over a 1-hour period to less than 20% of one pixel on the detector, or 0.0002 inch," says Hood. "And that's over a length of 1,500 mm."

Robust recorder. NICMOS and STIS aren't Hubble's only new tools. A solid-state re-corder developed by NASA Goddard (Greenbelt, MD) replaces one of the three existing reel-to-reel tape recorders. The 25-lb device not only offers 10 times the data-storage capacity in the same volume but can record and play different sets of data simultaneously--a significant advantage.

Its memory consists of 320-Mbit DRAM stacks developed by Irvine Sensors (South Burlington, VT) arranged on two boards for a total of 12 gigabits of storage. Processing is handled by the "Mongoose," a RISC-based, radiation-hardened microprocessor developed at Goddard. A Reed-Solomon encoder/decoder chip adds additional bits of information to stored data for error handling.

The SSR further adds robustness with its ability to map storage around bad or failed memory areas. This eliminates a tape recorder's Achilles heal--the tape. "If a tape breaks you lose everything," says Steven Horo-witz, lead engineer at Goddard.

But the SSR's greatest benefit is in assisting Hubble to reach its full potential. Says Horowitz, "NICMOS and STIS produce so much data that they need the SSR to fully exercise their capabilities."


Isolator cuts earthquake damage

Avignon, France--The building sways. If it sways too far, it can be severely damaged--or collapse. But that's highly unlikely in a steel-frame or reinforced-concrete building built with the Paraseismic Isolator Support system from A.A.I.P.S. (Ap-pareils d'Appuis Isolateurs Para Sismiques).

The system is located between a building's underground foundation substructure and the base platformof its above-ground superstructure. It consists of two solid blocks of Bayer Vulkolan elastomer, one embodying a horizontal friction plate with a truncated cone in the middle, the other a flat-topped circular cap that fits over the cone. Either block can be attached to the substructure, with the other attached to the superstructure.

The space between the blocks is filled with one or more vibration-proof crowns. Layers of a supple polymer material are laid horizontally.

As an earthquake starts, the layers of polymer allow some degree of multidirectional swing between the building's substructure and superstructure. Under more intense shaking, the two parts can slide and rotate relative to each other. However, much of the seismic energy is absorbed and dissipated, thanks to the deformability and damping capacity of the isolating materials.

Once the earthquake is over, the central crown acts like a giant spring to restore the superstructure safely toits original position. What's more, this same spring action can compensate for slow foundation displacement due to soil moisture variations or clay compaction. The supports also can be installed underwater.

Easy to use, the system comes in many configurations, with thicknesses, sizes, volumes, and shapes determined by the loads it supports. It can be employed on individual houses, large buildings, or civil-engineering facilities.


Software helps company brush up design

Palo Alto, CA--When Oral-B Laboratories approached IDEO Product Development with a compact interdental toothbrush design, their primary concern was time. The company wanted to bring the product to market in eight months.

"Oral-B's prototype had a limited stroke, no protective cap, and a problem with the brush head coming unscrewed," says IDEO engineer Dave Lyons. "Our job was to make it work." The result: IDEO completed the design phase in less than six weeks using SolidDesigner software from CoCreate Software Inc., Fort Collins, CO.

The final toothbrush design comprises a handle made of two halves that slide with respect to each other. With the two parts together, the head is in line with the handle, and can be used to clean the teeth and gums in the front of the mouth. Sliding the handles apart bends the brush head up to 90 degrees, reaching rear teeth.

The brush's body is made from Monsanto Santoprene, an injection-moldable elastomer. Four molded "living hinges" and a snap-fit detail provide articulation.

The main body is molded in the open position, and the wire stem below the bristles is insert-molded into a boss in the center of the four hinges. The brush is then folded, and the two handle-halves snapped together at the sliding snap-fit detail. A clear protective cap snaps over the brush head.

Lyons used SolidDesigner to determine the interaction of the two halves of the handle and to design the snap detail for the cap. He credits the software with helping IDEO meet Oral-B's time line.

"What made the project so successful was the ease with which we transitioned the 3-D database to tooling vendors," says Lyons. "Real savings were made downstream in the development. Surface data from the SolidDesigner parts were used to create cavities of injection-mold tools."


Reduced costs driving concern for auto engineers

Detroit--Cost reduction is far and away the number one challenge facing automotive engineers and designers. At least that's the result gleaned from a survey sponsored by DuPont Automotive and the Society of Automotive Engineers (SAE) of attendees at this year's SAE International Congress and Exposition.

"For the past few years cost was a significant concern, but this year it is the only concern," reports Erik Frywald, DuPont Automotive's director of engineering materials. Fifty percent of respondents listed cost reduction as the top priority, outranking all other considerations, including foreign competition, recycling, fuel economy, safety regulations, and quality, by more than a 30% margin.

Not only is cost the primary concern, the survey shows, but the industry is finding better ways to evaluate total cost. Nearly 70% of the respondents said they have systems in place to account for final assembled costs of a component or system.

Materials suppliers like DuPont can help automakers meet their cost-reduction goals, according to Fyrwald. "Materials suppliers need to partner with the automakers and play a visible role in advanced concept development so the right materials are being selected for the right use."

Based on the SAE survey, the industry agrees. Nearly 90% of those surveyed said materials suppliers play an important role in the pre-concept and concept product development process.

Automotive Consulting Group, Ann Arbor, MI, conducted the survey for DuPont and SAE.


Catera: A driver's Cadillac

by Brian Hogan Managing Editor

Dover, MA--Whether it's fair or not, most people think of cars from Cadillac as oversized iron lumps with mattress-type suspensions, designed for older drivers whose fat wallets come attached to bloated egos. If the new mid-sized Catera catches on, that perception will change.

No kidding here, Catera is a neat car. During a week of city and highway driving, I found Catera quick, nimble, comfortable, and just plain fun. I hated its cup holders, but literally everything else about Catera was delightful.

Of course one reason for this excellent result might lie in Catera's family tree. Basically, the car is an Americanized version of Opel's Omega MX6 Sport Sedan. Assembled in Germany, it features a German-designed engine assembled in England, and other components from the U.S. and France.

Cadillac gave the Catera full luxury features: power seats, a great sound system, dual-zone automatic climate control, remote keyless entry--all the things you'd expect in a U.S.-built luxury car. But they kept the fundamental package intact.

Catera comes with a 3.0l, double overhead camshaft, 54-degree V6 rated at 200 hp at 6,000 rpm and 192 lb-ft of torque at 3,600 rpm. The 54-degree layout reportedly reduces the engine's weight by 15%, and reduces rotating inertia by 28% when compared to the previous Omega Six. Engineered by Adam Opel AG in Germany, the 24-valve engine has a three-stage induction system that maximizes power output, and a compression ratio of 10:1. Top speed is electronically limited to 125 mph. Catera's four-speed automatic transmission uses adaptive logic to optimize shifting. There are three shift programs: Normal, Sport, and Winter.

Catera offers four-wheel (ABS) disc brakes and traction control; if a driver wants to lay rubber, he or she can switch off the traction control. The car uses a MacPherson strut suspension in front, with a multilink rear suspension. Automatic load leveling keeps ride height constant even with the vehicle fully loaded. Speed-sensitive steering varies power assist according to vehicle speed, and steering requires three turns lock-to-lock. With a steering ratio of 13.5:1, Catera has turning ratio of 34.12 feet.

Interior space on the Catera pleases the soul. Its rear seats actually allow normal-sized adults to ride back there without pain. (One minor point: This mid-sized car is the tallest vehicle in Cadillac's lineup at 57.4 inches.) Vision from the driver' position is excellent, and Catera has a four-position adjustable steering wheel. If you drive the car, you'll find its analog instruments easy to read. The switches and knobs that control Catera's collection of gadgets are convenient. Switches that control the sound system proved a bit too convenient; this driver kept tapping them as he drove, changing stations, volume, etc. But over time I adapted.

Would I like to have a Catera in my garage? Yes. No qualifications on that response. Unfortunately, my Catera carried a sticker of $36,665, not including taxes--a bit steep for a struggling editor. But if you're in the market for a luxury sport sedan, check out this Teutonic Caddy. It's definitely worth a look.


Software accelerates roadster design

Las Vegas--Carroll Shelby, founder of Shelby American Inc. and three-time winner of the Sports Car Driver of the Year award, has made his mark again, and just in time to celebrate his company's thirty-fifth anniversary. The Shelby Series 1 sports car is powered by a modified Oldsmobile Aurora V8 in a rear-wheel-drive setup.

For optimal handling, the car's semi-monocoque chassis, designed with CADKEY, has a fully independent suspension with a rocker-arm configuration and inboard-mounted coil-over shock absorbers.

The roadster's carbon-fiber composites and lightweight components keep the target weight at 2,300 lbs, with the body shell weighing in at less than 100 lbs. Aerodynamics induces downforce and dissipates heat. Computer analysis predicts acceleration from 0 to 60 mph in under five seconds and a calculated top speed of 170 mph.

Shelby engineers used CADKEY software from Baystate Technologies, Marlborough, MA, to significantly shorten the development time of the Series 1 prototype's key components. For example, instead of supplying individual line drawings to the machine shop, all of the aluminum-suspension pieces were milled directly from 3-D CAD models.

"From interference checking to visualization, the advantages of three-dimensional modeling in CADKEY were substantial," says Shelby American's Director of Engineering and Design, Peter Bryant. "The software enabled our engineering team to productively focus on inventing and communicating breakthrough automotive technologies, instead of worrying about the mechanics of the CAD system."

Running prototypes will be ready for testing and appearance at various Oldsmobile functions, including the 1997 Indianapolis 500.


Implantable pump stops deadly fibrillation

Minneapolis, MN--Atrial fibrillation (AFib), an extreme form of arrhythmia, can cause both of the heart's top chambers to stop beating and start to quiver. AFib affects more than six million people worldwide and causes more than 75,000 strokes per year in the U.S.

An implantable pharmacologic atrial defibrillator designed and patented by Robert Arzbaecher, director of Illinois Institute of Technology's Pritzker Institute of Medical Engineering, is being developed for the market under license by PharmaTarget Inc. The company says that initial introduction of the device should take place in Europe in about two years.

About the size of a hockey puck, the implantable device monitors the heart's electrical signals to detect any irregularity. A special catheter/lead, fixed in the right side of the heart like a pacemaker lead, connects the heart to the defibrillator. A microcomputer analyzes the heart's electrical signals. When an AFib episode occurs, the computer starts a drug pump to deliver a physician-prescribed dose of anti-arrhythmic drug directly into the heart, restoring normal function. Drugs are used only when needed, at the site (the patient's heart) where they're needed.

Today, the standard treatment for AFib requires either electrical shocks to the heart or drugs delivered intravenously. Patients then go on a lifelong drug program that can cause serious side effects. The new device should not inflict the pain sometimes associated with electric shock, and could reduce or eliminate the side effects associated with long-term drug therapy.

PharmaTarget intends to call its new medical device the Implantable Pharmacologic AtrioverterTM, or IPA. This spring, 31 electrophysiologists from the U.S., Europe, and the Pacific Rim will begin a series of clinical studies on the effectiveness and safety of delivering drugs directly into the heart, and the effectiveness and safety of the IPA.


Materials help new Corvette remain a 'classic'

Detroit--When an American icon like the Chevrolet Corvette is redesigned only five times in its 44-year history, customer expectations can be demanding. However, the fifth-generation 'Vette won critical acclaim at the 1997 Detroit Auto Show.

"Styling is expected to be distinctive, quality is critical, and the entire team knows they're producing something that will be valued and collected for decades to come," says Fred Kulka, engineering group manager-exterior plastic parts for GM's Midsize and Luxury Car Group.

Helping to fulfill those expectations were requirements the vehicle's suppliers subscribed to and met. One such supplier, Dow Automotive, provided a material designed to cost-effectively facilitate the needed styling flexibility for the fenders and front and rear fascia.

Dramatic air scoops extend from the front of the vehicle to the doors and are key styling elements of the vehicle's exterior. The scoops are molded into the fender--a component that was not part of the previous generation's design. The fenders are reaction injection molded (RIM) by MAGNA Decoma Exterior Systems Polyrim, Thornhill, Ontario, using Dow's SpectrimTM BP-80 reaction-moldable polymer.

"Three-and-a-half years ago, when we looked at the design of the fenders on the new Corvette, everyone knew that RIM was the only viable alternative," Kulka explains. "The excellent engineering and production experience that we have had in the past on the Camaro/Firebird, as well as the GM APV fenders, acted as our guide."

The front and rear fascia had different production issues than the fenders. The rear fascia in particular had demanding requirements as to both size and depth, according to Ron Petry, Corvette release engineer, making Spectrim RIM the most appropriate choice.

"In this case, the large size and complex shape of the rear fascia helped dictate both process and material," Petry says. "Too many die-lock positions would have been required for TPO (thermoplastic olefin). With RIM, the molder can pull the fascia directly off the tool. RIM also permitted the most effective attachment system for both the front and rear fascia."

"Body panels and fascia for several new vehicle programs, which cannot be identified at this time, have been committed beyond the year 2000," notes Laurie Sargent, market manager for Dow Automotive. "If design flexibility at the OEM is to be adequately supported, then it remains extremely important to offer a high-performance product family like Spectrim. This allows the automaker an enormous range of capabilities as well as on-line paintability and excellent customer satisfaction."


Hal Rosen's powertrain hybrid

Woodland Hills, CA--Harold Rosen led the team that designed the first geostationary communications satellites ever built. Rosen spent 37 years at Hughes Aircraft Corp. He was awarded more than 50 patents and received many engineering awards, in-cluding the Design News Special A-chievement Award for 1992. Now, funded by his brother Benjamin, chairman and co-founder of Compaq Computer, Harold Rosen is developing a world-beater of a hybrid powertrain.

Rosen Motors' hybrid electric powertrain consists of a turbogenerator, a flywheel-driven motor-generator, electric drive motors, and an electronic control system. The flywheel has a carbon-filament-wound composite cylinder and ring, titanium hub, and steel shaft. Supplied by Capstone Turbine, another company with which the Rosen brothers are involved, the turbogenerator will burn gasoline in a catalytic combustor and also serves as a motor when starting the vehicle.

In the Rosens' powertrain, a dc bus connects all the motor/generator sets. A controller containing both logic and power sections governs all the motor/generator sets and monitors the bus voltage (nominally 400V). In milliseconds, the flywheel-driven generator either adds energy to or subtracts energy from the bus as bus voltage tries to fluctuate.

"In the process of accelerating the car with the drive motors, the flywheel starts slowing a bit," says Harold Rosen. When the controller recognizes the reduction in flywheel speed, "the turbine control system starts adding power to the bus, and that causes the flywheel to charge up," he explains. "It's a proportional control system, and it's a continuous system."

During operation on a test rig or in a vehicle, the electronic controller dynamically blends power from the flywheel-generator and turbo- generator to supply the drive motors. The drive motors are the only components connected directly to the drivetrain. Using a fixed-gear reduction, coupled with the characteristics of an electric drivetrain, result in vehicle acceleration as smooth as that achieved with a continuously variable transmission, according to Rosen Motors.

In the company's current system, the turbogenerator provides a maximum of 30 kW; future versions will utilize a 45-kW (60-hp) unit. The current design goal for flywheel self-discharge time is approximately 1,000 hrs, and the turbogenerator can recharge the flywheel. At maximum charge, the flywheel stores 1 kW-hr; of that energy, 80% can be recovered over the flywheel's operating speed range of 28,000 to 62,000 rpm. It can deliver or accept energy at a maximum rate of 150 kW.

At the present time, work continues on the turbogenerator's catalytic combustor. Until the unit reaches the level of performance desired by Rosen Motors engineers, the turbogenerator will use a conventional combustor.

Early this year, Rosen Motors successfully road-tested its powertrain in a converted 1993 Saturn at Willow Springs racetrack near Edwards Air Force Base. A second car, more of a prototype than the Saturn, is also being built. This latter car, a Mercedes Benz E-Class, has four motor/generators on board. Two drive-motors in the rear wheels function as generators during regenerative braking. Harold Rosen expects to see the E-Class on the road with its hybrid powertrain before the end of 1997.

Rosen and his colleagues say cars equipped with their drivetrain will a-chieve a fuel efficiency of 45 to 80 mpg and be capable of accelerating from 0 to 60 mph in six or seven seconds. They claim their type of hybrid system has many packaging advantages over hybrids that use batteries. "We don't need a purpose-built car," says Rosen, "our powertrain is not too hard to introduce into an existing vehicle."


Panel design enables easy access

Toledo, OH--When Owens Brockway needed to cool a new computer, the company knew that choosing the right air-conditioning unit was critical. Owens, which makes glass and plastic containers for consumer products, chose a 1S Pro-Ozone air conditioner from Rittal Corp., Springfield, OH.

"Being able to easily change parts without much downtime was important," says Steve Cisco, an electrical engineer at the company. "And easy monitoring of the temperature was also key."

Interchangeable cover grills integrated into the unit provide the quick and easy access during maintenance that Owens desired. And an integrated microcontroller with touch-pad programming and a C or F temperature display option permits instant system analysis. Plus, the microcontroller can be integrated into a central computer system, enabling users to monitor the functions of many climate-control components at once, even from remote sites, to ensure reliable operation.

"The microcontroller technology enables us to set and view the temperature within the enclosure without having to open it up," explains Cisco. "And being able to connect the microcontroller to other systems to monitor the temperature is a big help. For example, we are now monitoring the temperature using the computer that is inside the enclosure being cooled."

Easy installation is another benefit of the Pro-Ozone units. Side-mounted models can be installed with no special hardware, using only eight mounting studs. They can be placed either on the enclosure surface, or partially or fully recessed into the enclosure.

Smaller mid-size 1S air conditioners also aim to make servicing easier. The units feature front-vented panels that snap off for easy maintenance and replacement of filters. They offer simple temperature control through a standard built-in thermostat as well.


European gasket gains foothold in U.S.

Wayne, NJ--What do six European first-tier suppliers have in common? All have practiced Form-In-Place (FIP) gasketing of automotive rear-light assemblies for two to four years. Savings range from $1 to $2 per car, with payback for the new equipment averaging 18 months.

Six years ago, the Foams, Films and Laminates Business Unit of Norton Performance Plastics Corp. developed Dynafoam(R), a single-component, rubber-modified polyester gasket material. The thermoset is applied in place and cures quickly when it reacts to ambient humidity.

Dynafoam holds its shape right out of the nozzle without slumping or running, even when applied on an incline or upside down. This proves to be a key benefit. For example, many newer vehicles feature tail lamps that wrap around the rear of the car to provide side lighting. Dynafoam's ability to maintain its shape facilitates such custom transfer-molding operations. About half of the European light suppliers combine Dynafoam with transfer molding to achieve gasket geometries not previously possible. They include such firms as Valeo in France, ITT in Germany, SIMA and Carello in Italy, and Altissimo in Spain. The gaskets can be found on Ford's Mondeo, Fiat's Punto, and Opel's Astra and Vectra models.

To create extreme cross sections and 3-axis gasket parts, engineers use a three-step process patented by Norton called gasket transfer molding. In the first step, Dynafoam is dispensed into a groove of a specially treated, wa-ter-cooled mold. The mold filled with the material is pressed onto the part being gasketed. Five seconds later, the mold is removed from the gasket, adhering to the part.

Depending on the size and shape of the gasket, total processing time ranges between 7 to 20 seconds. If full cure is desired, the gasketed part is processed in line through a humidity cabinet for 12 to 20 minutes and then packaged.

To date, more than 2 million European cars carry rear-light assemblies based on the molding-material duo. Major lighting assemblers in France and Germany that have incorporated the innovation into their assembly lines have cut gasket installation costs as much as 55%, eliminated production bottlenecks, and, in some cases, cut material use per gasket by 7:1.

Now, several U.S. rear-light applications using the process are in development.


Threaded fasteners get tough with PEEK

Santa Ana, CA--Over the years, Textron Aerospace Fasteners has offered threaded fasteners in a variety of materials. However, when it comes to thermoplastics for its line of ACP fasteners, Textron turns to PEEKTM.

One reason for the popularity of the material: its resistance to a wide range of inorganic and organic chemicals. "PEEK polymer has excellent properties and superior test data," says Clyde Simmons, technical services engineer at Textron. "Customers like the higher strength and temperature resistance of PEEK, as well as its ability to maintain mechanical properties in harsh chemical environments."

The polymer fasteners see service in aerospace, marine, medical, sporting goods, and recreational applications. In the aerospace arena, for example, they can significantly reduce the weight of fastening systems, while providing ample strength in structural and non-structural uses. "PEEK fasteners can cut weight by up to 80% when compared to current metal fastening systems," Simmons explains.

In marine applications, customers turn to PEEK because of its corrosion resistance. "In waste holding tanks, fasteners made with the polymer have excellent performance in the highly corrosive environment," Simmons notes.

Yet another reason for choosing PEEK, adds Simmons, is that it has minimal interference with electronically sensitive applications such as radar equipment, instrument housings, and brain-scanning equipment.

For these applications, Victrex USA Inc., West Chester, PA, supplies Textron with its Victrex(R) PEEK polymer.

Sign up for the Design News Daily newsletter.

You May Also Like