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Articles from 1995 In June


Electric Eye on the Bottom Line

Electric Eye on the Bottom Line

It's best to be nimble when you walk among giants. That approach best describes Scientific Technologies, Inc.'s (STI) way of manufacturing factory-automation equipment. The Hayward, CA, company deftly balances engineering creativity with manufacturing pragmatism. Business Week and Forbes call it one of America's best small companies. Its customers call it when they need monitoring and safety devices--fast.

Started with a $10,000 investment in 1971 by Anthony Lazzara, an attorney with a technical bent, STI has grown to a $26-plus million diversified electronics enterprise with three divisions: Optical Sensors, Control Components, and STD-bus computer-board-maker Datricon. Originally a family business, the publicly traded firm maintains the mom-and-pop virtue of a small management structure while paying close attention to the bottom line. At the same time, it embraces cutting-edge design and production techniques, strategic partnerships, and global competition.

"We want to be the number-one manufacturer of pulse-modulated infra-red scanners and light curtains," explains STI Vice President Jim Lazzara. In its market niche of safety interlocking devices, it's already number two and trying harder. The company has distributors throughout most of the developed world. A partnership with Guardmaster, Ltd., Wigan, England, a manufacturer of electromechanical safety relays, compliments STI's electronic safety products, making it a one-stop alternative for OEM designers.

World-wide perspective. The foreign connections help with technology development. "You've got to be in Europe," says Lazzara. "They're driving the industrial-safety standards for the rest of the world." STI's six different models of safety IR light curtains meet both North American and the more-stringent European standards. Each model includes sending and receiving units and a power supply/controller. The controller regularly monitors the system for faults. If it discovers a sensing-system fault, or if an object breaks the beam, the controller triggers a machine-stop signal in 45 msec or less.

Models range from the single-beam BeamSafe(R) through the OptoSafe(R) and OptoFence(TM) lines. The latter is available up to 96-inches high with beam spacing of 0.75 and 1.5 inches, respectively, with sensing ranges up to 100 ft. The modular FlexSafe(R) line simplifies machinery retrofitting. Its curtain segments interconnect with single cables to form appropriately shaped, continuous intrusion protection around punch presses, robotic workstations, or other machinery.

STI also manufactures a variety of profile-determining scanners, proximity sensors, pressure-sensitive floor mats, capacitive palm switches, and wireless communications equipment. For all its product diversity, the company's 20% average growth through the '90s came about through judicious acquisitions and empowered employees, maintain its officials.

Jeff Edwards, currently STI's MIS manager, illustrates the company's business technique. Edwards was one of five engineers to start Datricon, an STD-bus board maker for machine-tools. As he tells it, Datricon originally prospered, but got into financial trouble when it went public in the middle eighties. "Professional managers were brought in, but they were big-company types," he says. "They'd focus on reports, things that required more gloss and staff--things a small company can't afford."

Datricon was about to go into receivership when STI bought the company at a fire-sale price in 1990. Changes were swift. Layers of bureaucracy disappeared. "Everybody learned to wear four or five hats," Edwards says. Every task was flow-charted and examined to eliminate non-value-added activities. Today, the Datricon Div. is a profit center that nicely augments STI's portfolio of factory-automation electronics.

"Everything at this company revolves around reducing cycle time and boosting customer satisfaction," asserts James Ashford, vice president of Operations. Every product undergoes Pareto analysis to spotlight high-payoff design changes. Capital investments that lead to quality improvements receive quick approval. For example, STI was among the first U.S. companies to replace its bed-of-nails circuit-board testers with fully robotic equipment.

The company's flat management structure also contributes to production-cycle-time reduction. Practically every employee has a designated internal customer. Quarterly performance reviews weigh internal-customer satisfaction heavily. "It takes potential personality conflicts out of the equation," reports Ashford. With little bureaucracy, customer feedback can reach the proper person within the company quickly, often, says Ashford, within minutes.

For STI engineers, the open structure and emphasis on quick turn-around seem ideal. "We recognize that all your costs get fixed in design," says Ashford. "We develop a good product spec and target price that engineers need to meet, but don't necessarily restrict the technology they can use--that would stifle creativity."

The philosophy proves attractive. Jeff Edwards, the former Datricon manager, had just returned to the main plant from a satellite facility devoted to custom assembly. "I wanted work where design for manufacturability was more of an issue--a just-in-time, pull-type manufacturing process," he explains. "That's what we do here."

Application Digest

Application Digest

Simplified Magnetic Measurements Cut Costs

By Gordon Ross, Design Engineer, Honeywell Inc., Micro Switch Division

Reducing operating costs is a goal most companies work on continually-for their customers as well as for their own organization.

Design engineers focus specifically on finding cost-effective applications. On a more specific level, using a simple bench set-up can help you evaluate possible Hall-effect sensor applications. Applications using Hall-effect sensors can include but are not limited to bin-level control, joystick applications, ignition timing, position sensing, and vibration sensing.

Engineers can use a linear Hall-effect sensor instead of a gaussmeter for concept tryout in magnetic designs. This may be desirable for a number of reasons: lack of a gaussmeter, limited space, lack of modeling capability, or the need for a disposable probe. A linear Hall-effect sensor such as the SS94A2D from Micro Switch can be used as the sensing element. This will sense the magnetic field perpendicular to the surface.

Connect the linear Hall-effect sensor to an 8V dc power supply, which will give a meter reading of 1 mV/gauss. Adjust the trimpot so that the meter reads zero with no magnetic field present. The meter now will read 1mV/gauss for magnetic fields of -2500 gauss to +2500 gauss. If you're using a linear Hall-effect sensor with a sensitivity other than 1 mV/gauss, you'll need to divide the meter reading by the Hall-effect sensor sensitivity. Replace the voltmeter with an oscilloscope if you're measuring a changing magnetic field.

To speak with a Micro Switch applications engineer, call (800) 366-6786.


Analog Design Prevents Pointing-Device Drift

Melody Williams, Program Manager, Keyboard Division, NMB Technologies Inc.

Some notebook computer manufacturers using pointing-stick devices express concern about problems associated with strain-gauge pointing sticks.

Movement of the cursor on the screen when there is no touch to the pointing stick is called "drift." Drift may be caused by temperature change or by electrical noise affecting the pointing-stick circuit. The electrical noise may cause drift directly or defeat the algorithms that normally correct for slow changes.

Temperature change can occur either on the strain gauge itself or in the internal electronics. Temperature change occurring on the stick may cause the resistance to change if it influences only one of the strain gauges. Temperature change of the electronics due to heat inside the computer will also cause a change of input voltage. This change of input voltage will result in very small cursor-movement signals-less than one pixel.

The transfer function of the pointing stick, which is the translation of force to cursor movement, is structured so that forces less than several times the smallest force that can be measured result in no cursor movement. Therefore, the system detects slow changes and corrects them before any cursor movement is generated. To accomplish this correction, the software must distinguish between the signal caused by temperature change and the signal from a user's finger on the stick.

To make the distinction, the system looks at the steadiness of the signal. Temperature changes are consistently slow and steady, while a user's finger produces relatively rapid, not perfectly steady inputs. When the controlling software "decides" that the stick is not being touched, it recalibrates to a "zero" or "hands off" condition.

Excessive electrical noise in the circuits can defeat the software. Because the signals involved are only on the order of a few tens of microvolts, electrical noise interference can be avoided by good analog design work. Such designs require isolation of low-level signal nets and ground planes, careful grounding, and a reasonably stable power supply.

To speak with an NMB applications engineer, call (800) 662-8321.

Innovation shines in North Carolina

Innovation shines in North Carolina

Perhaps its climate gives North Carolina an unfair edge--especially in the springtime, when the sun is warm but not oppressive and the air smells sweet from a profusion of blossoming trees. But it's climate that the state pitches to lure high-tech companies to "Research Triangle:" not simply mild temperatures, but an environment conducive to business and innovation.

In general, the communities of Raleigh, Durham, and Chapel Hill form the Triangle's three sides. But within that triangle sits another: Research Triangle Park (RTP). In 1958, sensing the decline of traditional employers like the textile mills, North Carolina business leaders decided to get serious about courting new industries. Local businessmen raised funds to purchase the property, then established the non-profit Research Triangle Foundation to administer their site.

It was a far-sighted venture. Today, the 6,800-acre industrial park hosts 65 facilities and 35,000 jobs--many of them in product-development work. Numerous other businesses have sprouted up nearby. What follows is a sampler of some world-leading technologies flourishing in and around Research Triangle Park.

IBM's PC design site

While IBM has been hemorrhaging jobs for several years, employment at the company's Research Triangle site has remained at a constant 10,000 since 1985, a testimony to the Triangle's attraction as an R&D site. Why North Carolina? "Fine universities, a strong business-government partnership, and an excellent quality of life," IBM officials say.

Among the products developed here: System Network Architecture (SNA), basic software for connecting terminals running mixed applications; the Model 3689 checkout scanner, one of the first-ever commercial uses of holography; and the highly praised fold-out keyboard on the newest Thinkpad notebook PCs.

Now, most of IBM's PC-development work is being consolidated at the RTP facility, which recently marked its 30th anniversary. One benefit: Putting all the engineers together with manufacturing makes "concurrent engineering" easier, allowing team members from different disciplines to collaborate from a project's start.

The PC division uses CATIA solids-modeling and 3D Systems stereolithography in their work. "We can check the 3D parts to discover problems or mistakes much sooner than if we waited until the release of drawings," says industrial designer John Swansey. CATIA also allows engineers to deal with complex, curved designs, he adds. And, wireframe models are passed along for use in toolmaking.

The PC division's recent projects include the Aptiva for home use, and the PC 730 for the corporate desktop. While substantially different in outer appearance, the two PCs use the same frame; in some cases, there might be cutouts for parts, such as a fan, that are not used in one model. "The only difference is the plastic bezel and how you mount the drives," says staff engineer Ed Dials. Benefits: lower inventories and ease of switching models on the manufacturing line.

Elsewhere at IBM's sprawling RTP campus, engineers are developing credit-card-sized wireless devices that can serve as modems, fax cards, and network adaptors. One new device plugs into a Thinkpad PC for not only wireless data and fax transmission up to 14,400 bits per second, but conventional cellular voice calls with a plug-in headset.

The Wireless Modem for Cellular/CDPD and Advanced Mobile Phone System includes a radio running at 5V. To use it inside a laptop PC, engineers had to design not only for RF problems, but heat, shock, and vibration. IBM-designed silicon mounts directly on a board, with Motorola and Rockwell chips used as well.

Engineers solved the RF problems in part by designing a cover that isolates various components, while also protecting against computer interference.

"We did a lot of iterations," says Senior Engineer Bill Nunnery. "We don't have 100% simulation." Manufacturing engineers reviewed each proposal, including engineers in Toronto where the device would be made.

A pilot project at nearby Duke Medical Center uses another RTP-designed product, a Wireless LAN system, to let doctors access the hospital's Ethernet computer network anywhere in the building with a laptop PC.

"This technology can significantly change the way you live," Nunnery says.

With adapter, the IBM CDPD wireless modem for laptop PCs can also serve as a cellular phone to handle conventional voice calls. Engineers found challenges with RF, vibration, and shock in the design.

Bring the Infobahn to your door

Today's personal-computer modems typically transmit data at 14,400 bits per second. BroadBand Technologies has developed a system that will bring information into U.S. homes at speeds of 51 million bits per second.

"People have ridiculed it as a Field of Dreams: If you build it, they will come," says Donald McCullough at BroadBand. "But if you can move and process bits, there's a very lucrative market."

Consumers could access this network with a special TV box to tap into interactive video and movies on demand. Or, they could use specially designed modems for their PCs.

The network accommodates simultaneous uses in a household. A movie might run at 3 Mbits/sec, for example, and another live digital-video feed at 6 to 8 Mbits/second--still leaving 20 to 30 Mbits/second for high-speed Internet surfing. That would give at-home users practical access to high-resolution graphics and video clips on the Internet. "The local loop stops being a bottleneck," says Randall B. Sharpe, director of Advanced Technology.

A demonstration system at BroadBand's office features various movies on demand, as well as an electronic multi-media Yellow Pages you can tap into with a point-and-click TV remote-control device. The company is also working with Philips Consumer Electronics and Compression Labs to develop technology for interactive "video dialtone" service that will let phone companies offer video services over their local networks.

BroadBand's Fiber Loop Access (FLX) system relies on local telephone and cable companies upgrading most of their networks to fiber optics. The company's Host Digital Terminal in a central telephone-company office provides the interface between the voice and digital-data networks. Then, an Optical Network Unit brings high-speed data into 8 to 50 residences via an ATM (synchronous transfer mode) network. The total upgrade cost, including fiber optics, runs about $1,000 per home.

BroadBand's primary design challenge: keeping down costs. They developed more than a dozen customized chips for their system in an effort to devise an optimum solution. "We're very microprocessor intensive," Sharpe says. "Almost every board is intelligent."

Engineers at BroadBand have been working on their high-speed networking scheme since 1988--even before the overworked phrase "information superhighway" barged into the national lexicon. Now, as things like digital TV and Internet's World Wide Web are becoming popular, says McCullough, "We're happy to see that we were right. We just wish we could have made more money while we were right." But that, too, looks promising.

Last fall, BroadBand signed a deal with AT&T Network Systems to jointly develop a Switched Digital Video system to bring interactive multi-media to homes and offices. Pilot projects are already underway with Bell Atlantic and Southwestern Bell.

Working with AT&T Microelectronics, BroadBand incorporated an encoding and compression technique to allow high-speed data transmissions from the Optical Network Units into homes over conventional coax or twisted-pair cable. "The existing wiring and customer equipment remains intact," explains Gerry Pepenella at AT&T. "It brings us closer to the day when the public network can deliver a whole range of new combined voice, video, and data services into homes and offices at an affordable price."

"In the last year, we have achieved the cost breakthroughs necessary to meet telephone-company targets," McCullough says. "We believe we'll be producing large volumes in '96."

BroadBand Fiber Loop Access (FLX) system (below) carries high-speed data into individual homes. A Host Digital Terminal terminates narrowband, wideband, and ATM-based digital broadband signals. It then electronically multiplexes the signals into a single, high-speed data stream for transmission to Optical Network Units (ONU) by fiber-optic cable. The ONU terminates the fibers and demultiplexes the optical signals into telephone and broadband video signals for transmission from the ONU to homes via copper drop wires. Chip sets allow the signals to connect to digital "appliances' such as TV set-top boxes, home monitoring devices, and personal computers.

Materials for denser designs

As ever more electronics get crammed into the modern automobile, where can designers put them? And how? Can they be placed without complicating design and assembly?

DuPont Electronics believes it's got the answer: thick-film materials that can handle the temperature, shock, and vibration of an automotive environment. With more rugged electronics, parts manufacturers can incorporate electronics right into components such as anti-lock brakes. Having a complete assembly in one package, instead of running wires from the systems to electronic boxes elsewhere in the vehicle, makes assembly easier and cheaper.

Delco, for example, just announced it will use thick-film materials to produce a hybrid ABS circuit. Even more ambitious versions of the circuit combine anti-lock brake controls with variable-effect steering and traction control in a single system.

While thin films--often just a few atoms thick--may be "sexier," DuPont's Samuel J. Horowitz says thick-film technologies can offer radically lower-cost alternatives.

DuPont is extending thick-film technology through several patented processes that can form ever-smaller features. Conventional "screen printing" of circuitry offers hole sizes (vias) which connect adjacent cirucit layers of about 200 microns. For smaller features and greater circuit density, DuPont developed Diffusion Patterning.(TM)

First, a dielectric layer is printed onto a substrate and dried. Then, imaging paste is applied to spots where vias are to be produced. An activator diffuses into the dried dielectric layer. A final washing process removes the water-soluble material, creating 125-micron vias.

"Diffusion Patterning is extremely economical when you need the benefits of thick-film technology in conjunction with very high packaging density," according to a paper published by Dr. Hans-Dirk Lowe and Michael Kaindl of Siemens Electromechanical Components Div. Siemens first applied the process for custom automotive circuits, but the researchers envision the procedure being used in instrumentation and control, security systems, medical engineering, and aerospace tasks like avionics and radar.

For even finer work, Fodel(R) patterning creates circuitry by exposing screen-printed paste to ultraviolet light through a "mask" to create 75-micron features. And, low-temperature, coal-fired "green" ceramic tapes can produce circuits with up to 15 layers and 40-micron vias.

Car-radio maker Blaupunkt just adopted Diffusion Patterning for manufacturing high-density ceramic multi-layer circuits. The new three-layer circuit, with 200-micron vias, will cut circuit size almost one-third, and costs by 20 to 30%.

"The car radio of the future will have even more functions," Blau-punkt notes. "The available space and willingness of the consumer to spend more, however, is limited. Therefore, functions have to become smaller and cheaper."

DuPont Fodel(R) process can create 75-micron features using thick-film materials. Conventional thick film processes produce 200-micron holes.

Research for the real world

While many RTP companies work with the region's three universities, nowhere is the hand of academia more apparent than the Research Triangle Institute. Founded by Duke University, North Carolina State University, and the University of North Carolina at Chapel Hill, the Institute's mission is to apply basic R&D to the real world.

A case in point: Work in progress on using "fuzzy logic" to design controllers for variable-speed motors that would boost efficiency an estimated 3%. If used across the U.S., the controllers could save more than $2 billion each year in energy costs, Institute officials maintain.

"We take some very cheap measurements off the motor to predict speeds without actually measuring the speed," explains Dale Rowe, director of the Institute's Center for Digital Systems Engineering. "That's an order of magnitude cheaper than tachometer measurements."

Institute engineers are also applying neural networks--designing computers that try to mimic the workings of the human brain--for pattern recognition. Such a neural net will soon be put to work as a "cocaine sniffer," helping to track different batches of the illegal substance. Today, law-enforcement officials often boil samples of seized cocaine to create a gas-chromotagraphic pattern--and then must go through dozens of other such patterns on file to see if there's a match. A neural net could automate that process.

And, like the engineers at IBM, Institute researchers are working on low-cost wireless modems. Rowe believes with the emergence of several new wireless-communications standards, manufacturers are poised to include such devices in everything from hand-held computers to Coke machines (which could then tell a home office when they are running out of soda). "Within the next five years, this technology is going to explode," he says. "It's going to have more impact than any other technology I'm aware of."

However, the Institute's fastest growing computer technology is bringing virtual-reality technology to industrial customers for tasks like market research, design walk-throughs, and training. After two years in the field, the Institute already has a $6 million project backlog.

RTI recently developed a PC-based VR system for the National Guard that allows reservists to practice maintenance work on "virtual tanks." The problem, Rowe explains, is that when National Guardsmen have their two-week yearly drills, tank time is too important for drivers and gunners to have much left for mechanics. Conventional VR systems based on high-end hardware would help with training, but carry too steep a price tag.

Using Pentium PCs with graphics accelerators, Crystal Eyes stereo viewing glasses, and software from Autodesk (3D Studio) and Sense8 (World Toolkit), RTI developed PC-based VR training systems for less than $10,000 each.

"The initial reaction is that training time has been reduced at least four to one," Rowe says. "Now the regular Army is buying them."


Elsewhere in the triangle

A week-long visit isn't long enough to highlight all the high-tech companies in the Research Triangle. Others doing R&D work there include:

Computational Engineering International, RTP, a spin-off of Cray Research, developing FEA EnSight software used by companies such as Boeing and Nissan

Cisco Systems, Raleigh, NC, developing hardware and software for computers and routers

Data General, RTP, performing development work on its UNIX operating system

Electronic Equipment Analyzers Inc., Raleigh, NC, performing voice and data system engineering

Fujitsu Network Switching, Raleigh, NC, manufacturing phone switching equipment

Integrated Silicon Systems, Durham, NC, producing verification software for IC CAD

MTS Sintech, Cary, NC, making computerized testing equipment

Motorola, RTP, manufacturing computer equipment

NetEdge Systems, Durham, NC, developing computer networking

Northern Telecom, RTP, making digital switching equipment

Siemens, Wendell, NC, manufacturing switchgear motor controls

Tekelec Network Switching Division, Morrisville, NC, producing telecommunications switching products

Vertus Corp., Cary, NC, making 3-D software for interactively exploring a "virtual" environment

Powder Metal Gets Parts in Shape

Powder Metal Gets Parts in Shape

Princeton, NJ-What metal-forming process brings your part closer to final net shape, saves money, and lets you tailor performance characteristics? Powder metallurgy.

In the design of rifles, automotive fuel-injection systems, and computers, engineers are discovering the process efficiency and cost benefits of powder metallurgy (P/M).

The P/M parts business is maturing into a more solidly financed industry investing in new and more-sophisticated production equipment and improved quality control systems. The conventional P/M parts business, including in-plant operations, recorded an estimated $1.5 billion in sales in 1994.

More and more P/M parts are being designed into engines, transmissions and anti-lock braking systems (ABS). With a strong automotive year in 1994 when light-vehicle sales reached 15.1 million units, P/M experienced a substantial increase in business. GM, Ford, and Chrysler are all designing more P/M parts in North America and around the world. Hot spots include bearing caps and powder forged (P/F) connecting rods.

About 38 pounds of P/M parts go into the average Ford auto. This is expected to increase to 50 pounds by the year 2000.

Zenith Sintered Products, Inc., Germantown, WI, recently negotiated a five-year contract with GM for a new P/M steel bearing cap for its V-8 engines. Zenith has produced more than 10 million caps since the summer of 1993 for 3.1- and 3.8-l V-6 engines. Chrysler and Ford will join GM in designing with P/M bearing caps.

Ford is developing an engine bearing cap for the 3-l V-6 Vulcan engine. V-6 and V-8 engines can use between 4 and 14 pounds of powder in bearing-cap applications.

Near net shape. "One of the biggest benefits of powder metal is that the part is significantly closer to the final net part shape," explains William Jandeska, manager of P/M Technology for General Motors Powertrain division in Pontiac, MI. "Because of that, the part is less expensive overall, even though the blank is more expensive."

Powder forged connecting rods are replacing both cast and conventionally forged rods at the "Big Three." Twenty-five million conrods have been used in Ford engines without a failure-an enviable record.

P/F connecting rods are growing in popularity. Engineers designed P/F rods for the following Ford engines: 1.9- and 2.0-l 4 cylinder; 2.5-l 6 cylinder; and 4.6-l 8 cylinder 2-valve and 4-valve. In addition, P/F rods are slated to go into the new six-cylinder, 3.0-l engine for the 1996 model year and the Sigma engine to be made in Europe. GM uses P/F rods in the 4.6-l and 5.7-l V-8 engines, both operating in 1995 cars. GM is also considering P/F rods in its V-6 engines. Chrysler uses P/F rods in its 2.0-l and 2.4-l engines and is considering P/M in several new engines.

General Motors uses P/F conrods for the Premium V 4.6-l V-8 engines. The rods have an ultimate tensile strength of 110,000 psi, a yield strength of 50,000 psi, and an endurance limit of 40,000 psi. Powder metal contributes to important characteristics such as straightness, uniform microstructure, dimensional control, and superior machinability. P/M also eliminates surface defects inherent in conventional forgings.

Automotive parts such as bushings, filters, and oil-impregnated materials also benefit from P/M, says Jandeska. "With P/M, you get controlled porosity and other characteristics that can't be achieved with other processes," he adds.

P/M processes allow engineers to combine materials that can't typically be mixed together, such as aluminum with silicon carbide as the reinforcement for metal matrix composite. "This can be done by casting, but with the P/M process, you can have much finer-size silicon carbide to enhance the machinability and properties," says Jandeska.

For example, in GM valve guides, engineers use a ferrous material with hard phase formers for wear resistance and solid-state lubricants for lubricity. The materials are mixed together, pressed into shape, and sintered in an oven. "P/M accommodates a variety of different phases to offer different properties-in this case wear-resistance and lubricity," says Jandeska. "You can tailor the properties by mixing various different alloys or constituents."

Stainless-steel P/M applications are growing, especially for ABS sensor rings, which use 400-series grades. There is also a resurgence of interest in aluminium P/M among auto engineers as a way of meeting fuel-economy goals.

New techniques. Metal powder manufacturers are offering new products and improving the quality of materials. Many powder producers are pursuing ISO 9002 certification.

Several iron powder companies are pursuing warm-pressing technology for high-performance applications, which should open up new markets for P/M.

Water-atomized fine powder in many alloys is now available with higher tap densities. Engineers have developed new sizing technology to make very narrow size distributions for metal injection molding and other fine-powder applications.

P/M intermetallic iron alloys that resist high-temperature oxidation and nickel aluminides offer high-temperature strength and excellent corrosion resistance. Interest in better corrosion-resistant 300-series stainless steel continues to grow, and auto engineers are considering P/M for exhaust-system parts.

Equipment suppliers are in the forefront of upgrading P/M technology through improved or new production equipment or processes.

For example, engineers are using nitrogen-generated sintering atmospheres at customer sites. The technique is becoming popular because of its cost-effectiveness and convenience.

Compacting press suppliers are working more with powder and tool makers and customers to increase densities through higher-temperature sintering and improving densities through warm pressing.

MIM applications growing. The worldwide market for metal injection molding (MIM) is growing rapidly. U.S. sales of MIM parts are currently more than $60 million, with Europe at $15 million and Japan in the $35-50 million range. Japan is estimated to have as many as 100 companies involved in MIM. New automotive applications include parts for fuel-injection systems, anti-lock brakes, and airbag units. Additional markets include firearms, computers, and biomedical products.

For instance, Remington Arms Co., Ilion, NY, recently designed a .22 rifle around the advantages of metal injection molding. The rifle uses a MIM bullet magazine, trigger, and sight components. The one-piece complex magazine has a tensile strength of 55,000 psi and a 25% elongation. The part has sufficient strength in the feed lip area (open end of box) to resist deformation from .22 caliber cartridges while under pressure from the spring.

P/M will continue to erode the low- to medium-density machined forgings market by using new density-enhancing processes. With each gain in cost-effective density above 7.4 g/cm 3 a new range of applications opens up.

Engineers are also exploring brazing of P/M assemblies in new applications. There should be an increase in the use of brazed P/M assemblies which could open up more applications in 1995, especially competing against small castings.

All sectors of the P/M industry in 1994 recorded outstanding results. Metal powder shipments exceeded expectations with North American iron powder shipments soaring by 17.4% to 337,847 tons-a record. Overall iron powder shipments have increased by about 50% in the last three years. Copper and copper-base powder shipments experienced a much less dramatic increase of about 4% in 1994. The P/M business climate in 1995 looks equally good, with new parts being designed in many industrial and consumer products.

"Everything I see and hear is very, very positive about the current state of the P/M industry," says Armour Swanson, chairman of Zenith Sintered Products and president of the Metal Powder Industries Federation. "Most companies are increasing capacity to prepare for additional growth for applications now being tooled."

Powder metallurgy will continue to provide creative solutions to design and materials problems as engineers search out new and better ways to manufacture precision components.

Design's next step: Serviceability

Design's next step: Serviceability

You may never be rid of your next design. Whether cars or capital goods, a changing economy means that more and more products are being leased. Products that are sold need ever-longer warranties to stay competitive. And environmental laws in some places already require manufacturers to take back worn-out products for proper dismantling and disposal.

Engineers looking at longer-term responsibility for their products have two choices: Design them so they'll never break, or more realistically, design them so they're easy to fix.

This trend can best be illustrated with actual product examples. The thread that ties them together: serviceability design extends the concurrent engineering and quality design practices many companies already have in place. The added brainpower needed to make them successful pays off. As the B-school graduates say, "it's not a problem, it's an opportunity."

Expanding markets. Ingersoll-Rand Co., Washington, NJ, lays claim to being the largest manufacturer of centrifugal air compressors in the world. Over the last five years, its Centrifugal Compressor Div. spent $30 million on capital improvements to its plant in Mayfield, SC. Quality rose to the point where, with predictive maintenance like signature analysis and periodic oil and water testing, its API-compliant compressors now go five years between overhauls.

Yet, for all the improvements, the company shied away from specialty applications in large chemical, petroleum, and other process industries. These one-off applications usually involve designing the compressor with ancillary equipment to contractor specifications. Although potentially lucrative, the ad hoc engineering entailed added costs with little residual benefit to the company.

The solution, says George Kopscick, product manager for engineered products, was a clean-sheet design effort involving engineers, manufacturing people, service personnel, and customer representatives. As he explains, "We asked what we could bring to market that nobody else does." The answer: less frequent, and easier system maintenance.

To make that happen, the team adopted a number of special design criteria. Among them:

Add space for unrestricted access to every major component.

  • Place all maintenance/adjustment features within reach of the outside edge of enclosures

  • Include consolidated, maintenance-free stainless steel reservoirs.

  • Require flange connections for all auxiliary components for easy replacement.

  • Make all lube-oil components bracket-supported to the base to prevent breakage.

Introduced last March, the Process Package Air Compressor features a range of options such as cooling and lubrication components pre-engineered to work together. For example, in applications using silt-laden river water for cooling, an external water-through-tube heat exchanger replaces the conventional internal cartridge configuration.

When the tubes become clogged with silt, workers simply remove two end bonnets and clean the tubes with rods or high-pressure water. Total down time: three hours compared with 24 or more to replace a cartridge. The design, says Kopscick, has prompted several petroleum manufacturers to abandon their internal specifications and request strategic partnerships with IR for the compressors. The new low-maintenance design required no magic, he adds. "We just asked our customers what problems they were seeing in the field, then we brought our knowledge to bear to solve them."

Improve customer loyalty. Roger Smith, former GM chairman, was roundly criticized in the mid-eighties for saying that the best alternative to a inexpensive foreign car was a used Buick. Perhaps he was just prescient. With today's higher car prices, many manufacturers tout their cars' quality, low maintenance costs, and resulting higher resale value. In fact, maintainability has become a major marketing tool.

The quest for customer loyalty also has lengthened automobile warranties. Volkswagen, for example, recently introduced a 10-year, 100,000-mile warranty on selected models. Tim Lintz, advanced service readiness team leader at GM's Cadillac/Large Car Div. (C/LCD), Flint, MI, puts it simply: "If we can assist with engineering a vehicle that's less costly to service, it will be less costly to the corporation to issue a warranty."

General Motors uses a codified approach to design for serviceability. Service Engineering forms a part of GM's four-phase Product Program Management Vehicle Development Process, its term for concurrent engineering. Each design engineer gets a copy of GM's 100-plus-page Serviceability Design Guidelines. In it, they find recommendations for best practices in engineering every component in a modern automobile, including such minutia as towing, shipping, and a vehicle's compatibility with automatic car washes. In addition, the company has a separate Service Technology Group. Its representatives meet with all platform teams as new-car development begins.

"We go through a bi-weekly "wall walk," where production-assembly documents are posted that show how we plan to build the vehicle," explains Lintz. In general, the simpler it is to assemble a vehicle, the easier it is to access a part for service later on.

GM design teams have two options for rating component serviceability. The company has proprietary software that estimates labor time and expense based on historical repair data. This option is used when preparing a business case for a particular serviceability design idea.

The company also uses a manual Serviceability Task Evaluation Matrix (STEM) for quick decision-making during engineering meetings. STEM criteria include estimated repair and maintenance time, part cost, diagnosis time, tool requirements, technician training requirements, and part availability (will it need a special order or can customers pick it up at K-Mart?). The matrix assigns point values in each area, and users compare the totals for design alternatives to help make a decision. Key to effective use of the matrix: knowledge of the competition. The Guidelines notes "a rating of 85 points for an oil-filter change may be worst-in-class, but 50 points for a transmission filter may be world class indeed."

Another problem complicates serviceability issues for auto designers. Some 70% of repair work is performed by local garages, not dealers. Companies can't control the quality of the independent mechanics, but the quality and cost of their repairs often reflects on the engineering of the car. Car companies disseminate service information as best they can. Likewise, engineers have to avoid designs that require unique tools or handling.

Electronic diagnostics spotlight the issue. The U.S. government requires manufacturers to share drivetrain troubleshooting codes with independent scan-tool makers. Where no mandate exists, as in body and chassis systems, proprietary communications protocols can blemish a good design's reputation with owners. "That's where we come in," says Paul Gallo, service readiness engineer at C/LCD. "We make sure that the data make it into service manuals."

Inevitably, service issues sometimes clash with manufacturing or product-specification goals. For example, automated laser welding of car bodies speeds assembly and improves chassis stiffness, an important ingredient in a rattle-free, well-mannered car. Unfortunately, separating laser-welded components damaged in a collision can be extremely difficult. In the give-and-take of concurrent-design meetings, serviceability advocates consider the company's competitive position and "what's right for the car," says GM's Lintz. "If we don't want a laser weld in a certain area, we support that with the time and cost of repair, and how it might affect the customer's insurance premiums."

Automating DFS. Building on the success of its Design for Manufacture and Assembly(R) (DFMA) program, Boothroyd Dewhurst, Inc. (BDI), Wakefield, RI, recently introduced Design for Service (DFS) software as a part of its DFA version 7.1. DFS calculates a serviceability index for a given design then walks engineers through "what-if" analyses to improve that rating.

Designers begin the serviceability analysis by entering a disassembly sequence of items and procedures into an interactive worksheet. This can be done manually or by importing items from a previous DFA structure chart. The software responds with questions as needed to flesh out the proposed procedure.

DFS incorporates a database with over 800 service events, including item-removal and insertion times, item- and tool-acquisition times, and component manipulation times. It uses that database to automatically generate a reassembly procedure and time estimate. Users then compare the estimates with design goals or with design alternatives.

With the software, designers can identify specific design problems that contribute to poor serviceability. For example, by comparing the part's expected failure frequency and impact with its service efficiency, they can quickly identify critical service shortcomings that contribute to owner dissatisfaction.

Peter Dewhurst of BDI explains, "DFS provides a systematic, quantitative method that allows users to step through the process and look at service tasks up-front-where problem, solutions, and costs can be recognized while change is still possible."

Is serviceability the last of the contending design criteria that engineers must face? No, says Dewhurst. Regulations and changing consumer attitudes will increasingly make recyclability an issue as well. Fortunately, serviceability issues, properly addressed, also will simplify recycling issues.

MSC/NASTRAN for Windows

MSC/NASTRAN for Windows

The Windows interface in MSC/NASTRAN has a menu bar where all commands can be accessed. Menus drop down to dialog boxes where user input is requested. Coordinate entries and entity IDs can be input with the keyboard or selected from the model using the cursor.

A toolbar provides a graphical interface to some of the most commonly used commands. These commands include impressive dynamic rotation, panning, and zooming of the model. A nice feature is the user-definable toolbox, which gives users additional graphical access to the commands they use most.

SPEC BOX MSC/NASTRAN for Windows MSC/NASTRAN for Windows is a finite element program capable of performing static stress, buckling, and normal modes analysis; steady state and transient heat transfer analysis; static and transient nonlinear structural analysis; and structural dynamic analysis. It includes a Windows-based pre- and post-processor for the creation and viewing of your finite element model. Minimum requirements: Windows 3.1, 386 with math-coprocessor, 16M bytes of RAM and 100M bytes of free disk space.
List price: Prices range from $995 to $4,995, depending on capabilities.
MacNeal-Schwendler Corp., 815 Colorado Blvd., Los Angeles, CA 90041; ph: (213) 258-9111; FAX: (213) 259-3838.

The menus, toolbars, and toolboxes are easy to use and are a benefit in learning the program. They, along with a generous amount of hot keys, help speed the modeling process. However, I found moving down the multiple menus and dialog boxes to be somewhat time consuming. I would have liked the option of inputting commands directly using a command line.

Modeling capabilities. Elements can be created using direct generation, from existing geometry, or automatically inside a given boundary. The program's element library, along with its ability to specify material properties, loadings, and boundary conditions, should enable users to effectively model most structures and operating conditions.Translators are available to bring in geometry and finite element data from most popular CAD and finite element programs. Neutral files, which can be used to transfer information from one version of MSC/NASTRAN to another, can be exported. In addition, the solvers can be executed on any computer platform running MSC/NASTRAN.

The same interface used for model creation is used for viewing the results. Model parameters and analysis output can be sorted and listed in the format of your choice. Graphical output includes: deformation plots, contour plots, animation, criteria plots, isosurface plots, section cuts, and XY plotting of selected output. Animation and contouring can be combined, displaying contours animating in-sync with the displacements. Both the listed and graphical output can be copied to the Windows clipboard, to a file, or output to a printer.

Documentation. Included documentation will allow the user to learn to operate the program. However, there was not enough documentation to give the user a deep understanding of the program's workings. Information such as when to use what type of element and under what conditions these elements are accurate is not included. Nor is there any discussion of the solution-techniques used by the program to solve the models. I believe this type of information is essential in order to fully understand the accuracy of the results. By contrast, accolades are in order for the program's context- sensitive on-line help. It can be accessed at any time and includes a complete reference to all program features.

With its modeling and analysis features, MSC/NASTRAN for Windows offers the engineer a powerful analysis tool. Better documentation along with the option of inputting commands directly using a command line would be welcome additions. But the program shines in its ease of use, its listing and sorting of data, and in its ability to export data and graphics to the Windows clipboard, a file, or printer.


A similar product:

NISA - Engineering Mechanics Research Corp., Box 696, Troy, MI 48099; ph (810) 689-0077; FAX: (810) 689-7479.

OEMs are handing new tasks to diecasters

OEMs are handing new tasks to diecasters

A native of Great Britain, Keith Thompson became president of Dynacast's North American Region, based at Yorktown Heights, in 1986. From 1983 to 1986, he served as the firm's group manager, and was based at Dynacast's Schaumburg, Illinois, plant. During his time at Schaumburg, he was also responsible for diecasting plants in Montreal and Mexico, and for the company's Wisconsin tool center. He joined Dynacast at the company's Montreal plant in 1968. He became engineering manager at Montreal four years later, and general manager in 1976. Thompson attended McGill University in Canada.

Innovation means survival and prosperity as OEMs push design and assembly responsibility to diecasters, says Keith Thompson.

Design News: What changes do you see in diecasting industry?

Thompson: Our customers are expecting more and demanding more from us. We're moving more toward adding value, rather than just supplying a discrete component. This sometimes involves assembly, and sometimes involves purchasing other components and providing an assembled package to the customer. So our customers are looking for engineering solutions rather than buying discrete component parts.

Q: How does this trend affect your company?

A: We're doing more up-front engineering work and assisting in the design of the initial product, and we're doing more downstream in terms of added value. And I see a shifting of the burden from our customers to us. It's making our business more complex. We certainly still need tool designers, because the heart of the diecasting process is tooling. But in addition to tooling we're looking at adding more design engineers and process engineers. That's giving our business a direction it didn't have five to ten years ago.

Q: What has been the impact of CAD on precision casting?

A: It permits us to transfer geometry from our customer electronically, to do thermal analysis of dies, and to optimize runners and gating design. It has really changed the whole process of diecasting and tool making. Tool making is an integral, important part of our operation. And CAD/CAM has allowed us to reduce the time cycle for building tools, and is bringing us closer to the point where we make dies right the first time.

Q: How aware are design engineers of your industry's ability to diecast magnesium?

A: It's beginning to penetrate, but they're certainly less aware of the ability to cast magnesium than they are zinc or aluminum, which have been the traditional cast metals over the years. The magnesium industry is in an educational process. They're beginning to teach engineers the capabilities of magnesium, the advantages of the material. As time wears on, new designs in magnesium will increase the total volume of business.

Q: How much impact has robotics had on your industry and your company?

A: It's not part of our four-slide business, but we do have conventional equipment in some of our facilities. And where we have conventional equipment, we go with a manufacturing cell concept where we try to automate as much as possible. So in the larger conventional area, and particularly in plastics, we will move towards robotics to reduce labor costs, increase cycle time, and probably most important, improve quality. Robotics gives you consistent cycles and generally a consistent and stable process that improves quality. We'll continue to automate parts of the process, but we'll never see the day when we will not have skilled tool makers or skilled setup people.

Q: How much of your work involves an outsourcing relationship?

A: It's becoming a significant focus on the part of our business, and it's growing. Our customers are beginning to realize that they can't be experts at everything. And some vertically integrated companies have moved in different directions, wanting to outsource their injection molding or casting work. We feel our expertise is in the design and processing of precision components, and we can often do that cost-effectively for customers. We work hand-in-hand with many of our customers to help them outsource various aspects of their manufacturing in casting and injection molding.

Q: Why is there so much more growth in the use of plastics than in metals?

A: The metals people do very little to promote their materials. They basically dig metal up out of the ground and sell it at so many cents a pound. If you look at the plastics industry, they invest heavily in R&D and developing materials to gain new applications. But they also work with the customer base in developing technology and processes that open up new applications. Also, diecasting machinery manufacturers are light-years behind the molding machine manufacturers. Someone wanting to go into the diecasting business must cope with inferior machines, materials people who don't really promote the metals and work with you, and a process that's generally not as environmentally friendly as in processing resins.

Engineering News

Engineering News

Environmental concerns drive power-boat design

Newton, MA-Chariots of the waterways, power boats are racing across the nation's lakes and rivers in unprecedented numbers this summer, ferrying enthusiasts on joy rides that will refresh them for their work-a-day battles.

But, like their four-wheeled cousins that travel the roadways, power boats have run headlong into environmental concerns. The most recent manifestation: a U.S. Environmental Protection Agency proposal that sets forth the first-ever regulations for controlling emissions from outboard motors.

Specifically, the EPA wants outboard engine manufacturers to cut hydrocarbons releases by 75% in the next 10 years. Though the proposed regulations are still in the "public comment" stage and could be changed before the 1998 implementation target, engine manufacturers are already trying out new designs that will cut emissions without affecting performance.

Some manufacturers, such as Yamaha, may replace the traditional two-cycle engines they have been using with four-cycle versions up to about 50hp. But others are experimenting with new direct-injection two-cycle engines, which they say are lighter and more fuel efficient.

Two approaches. Traditional fuel injectors send fuel to an intake manifold where it vaporizes and drains into the cylinders. Direct injection sends the fuel straight to the cylinders without the need for a manifold. Two of the most promising direct injection systems are SEFIS (Small Engine Fuel Injection System), developed by Orbital Engine Corp., Perth, Australia and being used by Mercury Marine, Fond Du Lac, WI; and LEAP3 (Low Emission Advance Propulsion), from the German company FIGHT and being used by Outboard Marine Corp. (OMC), Waukegan, IL.

In SEFIS engines, explains Mercury Marine President David Jones, fuel rushes to the cylinder as a fine spray dispersed by an air blast after the intake and exhaust ports close. Unlike a similar automotive system from Orbital that derives air pressure from an on-board compressor, SEFIS captures a small part of the compressed air/fuel mixture above the piston by keeping the injector open until just before ignition. When it does close, it traps the compressed charge in an accumulator, where it can disperse the fuel spray in the next injection cycle. Jones says SEFIS improves fuel economy by 30%.

High-pressure pump. LEAP3 pressure-surge technology uses a high-pressure pump to blast fuel to the engine's combustion chambers. The pressure surge, at rates up to 100 times per second exceeding 200psi, atomizes the fuel as it enters the cylinder for a clean burn.

OMC engineers repositioned the intake and exhaust ports so both are closed when fuel is injected, and redesigned the piston head to provide more power with every stroke. "Traditional injection methods produce a stratified fuel/air mix-one that's richest at the area of injection and thinner in other areas of the combustion chamber," says Jack Flaig, OMC vice president for engineering and manufacturing. "LEAP3 produces a more homogeneous fuel/air mix throughout the chamber."

OMC President Hank Bowman claims LEAP3 computer-controlled direct injection technology is more sophisticated than that used on most advanced automobiles. He says it will result in a 35% increase in fuel economy.

Both SEFIS and LEAP3 technology have caught the eye of engineers in the general automotive industry. And, says OMC, LEAP3 has potential for use in lawnmowers and snow blowers.

Mercury plans to have SEFIS technology in place in 1996, the same time frame OMC is following for the LEAP3 technology it will put in its Johnson and Evinrude outboard motors.

Smaller wakes. Meanwhile, the need to meet local environmental regulations on wake production is driving other companies to develop new hull designs. Among them is Gallatin, TN-based Boating Corporation of America (BCA), which is experimenting with a new Stolkraft hull for its cruisers.

Developed in Australia, the Stolkraft design uses aerodynamic and hydrodynamic lift to provide what BCA calls an air-lubricated hull. Two geometrically shaped air scoops located at the bow between the hull route the air generated from the forward motion of the vessel to the aft tunnel for aerodynamic lift.

The air lift mixes into an air and water froth at the midship step in the hull, creating a lifting cushion of air and water for the planing hull to ride on this "air-lubricated" tunnel. Engines are located aft to keep the center of gravity on the aft tunnel and to keep the machinery out of the living area.

Clyde Head, BCA executive vice president, says a 26-ft-long Stolkraft hull running at 42 mph in calm water left only an eight-inch-high wake at a distance of 33 ft from the vessel vs the traditional five-ft wake for a so-called "deep V" design.

No spray. Of course, not all enginering work in boat design is for environmental concerns. Vonore, TN-based MasterCraft has just redesigned the hull of its ProStar 190 competition ski boat to dramatically cut down on the spray.

Twin strakes in the new hull knock down the spray before it becomes a problem, says MasterCraft's David Wilson. Then, deep slots in the hull channel it toward the back of the boat, where stepped chines flatten it and keep it close to the boat--and away from skiers.

Other developments on the horizon in power-boat design include multihulls, LCDs to display real-time engine data, fiber-optic cables to replace the hundreds of feet of corrosion-prone wires and connectors, and digital compasses with fluxgate technology to drive automatic pilots and sound "off-course" alarms.

Best of all, says boating author Gordon West, Costa Mesa, CA, marine electronics will have "off switches to shut everything down so boaters can just scan the horizon, take in the smell of the water, and enjoy life until an electronic alarm announces the dinner hour."

Strakes that deflect spray away from water skiers, as in this MasterCraft MarisStar, are among the recent advances in power-boat design.

SEFIS technology captures a small part of the compressed air/fuel mixture above the piston by keeping the injector open until just before ignition. When it does close, it traps the compressed charge in an accumulator, where it can disperse the fuel spray in the next injection cycle.

What this means to you

  • To cut air pollution, engineers have designed new types of 2-cycle engines.

  • The two most promising engine designs invovle computer-controlled, direct fuel injection.

  • Both systems increase fuel economy, and Detroit is interested.


GM engineer wins Lemelson prize

Washington, DC-William J. Bolander, a 34-year-old engineer with GM's Power train Group, received the first $500,000 Lemelson-MIT Prize for Invention and Innovation during a ceremony held at the Smithsonian's National Museum of American History in late March. A distinguished committee, led by Professor Lester Thurow of MIT, selected Bolander.

Presently employed as corporate algorithm technical resource leader with GM's Powertrain Group, Bolander is the inventor of the Cadillac Northstar's "limp-home" system. It enables a driver whose vehicle has lost coolant to travel to a service facility without experiencing engine damage. His engineering career has resulted in ten patents to date.

In an exclusive interview, Design News asked Bolander what significance the Lemelson-MIT award might hold for the design engineering profession. "I hope that it will raise the awareness in young people of what engineers are," he responded. "I've been shocked at the ignorance of most of the media people that I've been talking to. They don't know what engineers are and what we do. And if these adults don't know, our young people certainly don't."

In addition to Bolander's award, a Lifetime Achievement award was presented to William R. Hewlett and David Packard, founders of Hewlett-Packard Corp.

These awards were established by Jerome H. Lemelson, who was recently chosen "Engineer of the Year" by readers of Design News. The award received by Bolander will be given annually to an outstanding American inventor/innovator. It is reportedly the world's largest single prize of its kind. The Lifetime Achievement Award honors Americans whose careers as engineers and innovators have had a major impact on industry and society.

Lemelson funded the awards program, which is administered by MIT, in 1994. His purpose in doing so is to draw the attention of society, and particularly young people, to the importance of technology, and to make careers in engineering and science more attractive. "We glorify Michael Jordan and Tom Cruise," says Lemelson, "but the true heroes of our society are the men and women who solve our social and technological problems.


Aircraft-design winner sails into world championships

Sugar Land, TX-Last fall, Design News challenged readers to submit their aircraft designs to the Unique Airplanes contest. At stake: a Texas Instruments calculator-and pride.

Over the succeeding months, the postal carrier delivered a surprising number of entries. They ranged from rough conceptual sketches to multi-view CAD drawings. But one, Peter Masak's Scimitar glider, soared above the competition.

Many entries approached its creativity. Several very unusual proposals were more unique. However, none, save Scimitar, showed any promise of production.

A racing sailplane in the 15m class, Scimitar matches an advanced composite wing and empennage to a Schempp-Hirth Ventus fuselage. The result is an affordable, world-class competitive glider. Since most good fuselages affect overall aircraft performance insignificantly, Masak focused his effort where it counts-on the wing.

He began with a proven Wortmann airfoil section. To it he added an electronic boundary-layer control system (BLC) and winglets. An innovator in sailplane design-by day he's a mechanical engineer at Schlumberger-Anadrill-Masak developed the first successful winglets for gliders several years back.

The BLC consumes less than 15W and dramatically improves performance. "It's reduced drag in flight tests, at both low and high speed, by 15 percent," he says. "At the airfoil's design point there is no gain or loss, but a sailplane spends 99 percent of its time at the low or high end." He hopes to patent the BLC this year.

The wing consists of a fairly flexible S-glass spar and stiff kevlar skins. Masak tailored the structure to be soft in bend- ing but stiff in torsion. "We get superior twist characteristics as a function of speed," he explains. And the soft bending "reduces the local angle of attack during gusts to better keep the airfoil in the laminar-flow range." The wing is also the first to employ an optimized planform. Instead of easy-to-build straight-tapered sections, Scimitar's wing-geometry changes in three dimensions.

The design process consisted of classic techniques-an FAA requirement-followed by verification with advanced computer tools. Masak used Swanson Analysis' ANSYS to verify the wing structure. Several aircraft-specific programs, such as Stanford University's LinAir, assisted with wing-loading calculations and stability and control computations.

In January, Scimitar ventured to New Zealand for the 1995 world glider championships. "We were the first American team in almost 30 years to fly a glider built in this country," Masak says. Even more surprisingly, not one composite sailplane has ever been designed and certified in the U.S. Teething problems prevented Scimitar from placing, but even without the BLC system Masak says his aircraft equaled the best European machines.

Scimitar USA in Woods Cross, UT, will manufacturer and sell the new glider. The wings will be molded by Contour Composites (Salt Lake City). Following two years of testing, a Scimitar can be had for roughly $50,000-30 percent less than an equivalent German sailplane. Interested parties can call John Neel at (801) 298-2001, ext. 109.

Design News' Unique Airplane design winner Peter Masak poses at the 1995 world championships in New Zealand with his 15-meter class sailplane, Scimitar.

Scimitar's wing is flexible in bending and stiff in torsion due to a unique combination of an S-glass spar and Kevlar skins. It is the first sailplane to employ an optimized planform that changes in three-dimensions from root to tip. All other sailplanes use straight-tapered sections, which are easier to build.

-Mark A. Gottschalk Western Technical Editor


Brake-light design focuses on materials

Lisle, IL-Long before Design for Manufacturability became popular, Tricon Industries, Inc. simplified designs and reduced part counts by integrating components and connectors into a single, insert-molded part. The process, plus the selection of the right materials, paid big dividends when Inland Fisher Guide, Anderson, IN, asked Tricon to design and produce a new center-high-mount stop light (CHMSL) for Chevrolet and GMC full-size truck platforms.

Tricon's CHMSL design addressed a problem inherent in vehicle light assemblies. Over time, excessive heat buildup caused by multiple bulbs in a confined space can damage the polycarbonate (PC) fasia and cause warpage or twisting of the assembly. To prevent this, an open, rather than airtight, design was implemented to provide convective cooling. Extended metal back plates, which function as electrical conductors and as heat sinks, provide added heat dissipation. Molded-in "eyebrow" extensions above the bulbs further shield the PC lens from the heat source.

Key to the design is a 4-way integral connector and interconnecting stamped circuits, instead of four separate light assemblies. Power and signal lines are provided through a single plug-in cable connector. The 12-inch-long, single-shot molded component encompasses complex interior stamping and exterior interface geometries. Due to the complexities and tight tolerances, stampings are final-formed on demand at the insert molding machine.

Don Paul, Tricon's director of technical service and the company's Advanced Product Design Group, determined that heat deformation, warpage, and other performance problems could be prevented by careful material selection. The most common problems encountered in vehicle light assemblies: short circuits caused by water leakage and poor part fit, and part deformation resulting from moisture absorption.

Tricon consulted with Amoco Polymers, Alpharetta, GA, to find an easily molded, high-temperature plastic that would allow the 12-inch-long part to remain perfectly flat and stable. The resin selected: a 33% glass-filled custom blend of Amodel(R) PPA, a high-temperature engineering thermoplastic. The material's heat-deflection and temperature-resistance testing, Paul reports, proved it better than glass-reinforced nylon and other engineering-grade resins in its ability to remain stable despite heat buildup and moisture.

For the CHMSL's injection-molded bulb sleeves, Tricon chose high-temperature Ryton(R) PPS, Grade R-4XT, from Phillips Petroleum Co., Bartlesville, OK. This resin, says Paul, also offers the mechanical, thermal, electrical, and physical properties needed to withstand heat, moisture, vibration, and temperature extremes.

"These days, low part weight and long service life are high priorities for automotive manufacturers," Paul explains. "These materials allowed us to produce a part that satisifies GM's quality and performance standards, while assuring cost-effective, high-volume production."


Hannover Fair pavilions feature American innovation

Hannover, Germany-World class: It may qualify as one of the most over-used terms of the '90s, but it fits many of the exhibitors that lined the aisles of this year's Hannover Fair in Germany.

More than 7,000 international firms displayed their technology at the world's largest industrial fair, held the first week of April. Included in that group were seven American pavilions, representing 151 U.S. firms.

American exhibitors at the fair felt their presence there gave them a deeper understanding of the global market. "If you're not competing worldwide, saying that you're world class is a hollow mission statement," notes Ronald Bullock, president and CEO of Bison Gear & Engineering Corp., a motor manufacturer based in St. Charles, IL. "Here, you learn more about your global customers and your competitors."

Bison was one of 13 American companies exhibiting at the Power Transmission Distributor Association's (PTDA) Pavilion. Firms there introduced a multitude of new products, most aimed at the global market. Reliance Electric, for example, rolled out its IEC Metric Motor, which employs metric mounting dimensions and shaft diameters. Bison also introduced a global product: Its G-line of gearmotors, also offering metric mounting dimensions and shaft configurations.

Twenty American firms displayed their wares at the National Fluid Power Association Pavilion, including Auburn Gear, Bimba Limited, Fabco-Air, Firestone Industrial Products, Hobbs Corp., and Sun Hydraulic, among others. Most saved their global product introductions for the Fair. Fabco-Air, Gainesville, FL, for example, rolled out its Global Series of pneumatic cylinders. The firm also did a brisk business with its Multi-Power pneumatic cylinders, which already enjoy widespread use in the U.S., but are relatively new to Europe.

Exhibiting in a European show is critical for companies that want to forge business alliances abroad, says William H. Prueser, director of exhibitions for the NFPA. "The business culture is different in Europe," he explains. "You can't make cold calls on customers at their facilities. You have to get to know them first. At the Hannover Fair, you have a chance to make that initial introduction. That's why it's important to have shows like these."

Most exhibitors said they left Hannover with a better feel for the meaning of the term "global market." "You might come here thinking that you have only four or five competitors," notes Leslie G. Hennessy, vice president of marketing for Lovejoy, Inc., Downers Grove, IL. "But when you leave, you realize that you have 40 competitors."

The Hannover Fair, which attracted more than 300,000 attendees from around the world this year, highlights innovations in fluid power and motion control every other year. The Fair will again focus on those disciplines in 1997.

The Hannover Fair attracted more than 300,000 attendees from around the world.

Fabco-Air introduced its Global Series pneumatic cylinders at the Hannover Fair. Global Series cylinders incorporate special surfaces for mounting of stroke-sensing switches.

-Mark A. Gottschalk Western Technical Editor


Government plans to bolster 'green' design

Washington,DC-The White House has launched a nationwide program aimed at encouraging engineers to develop more environmentally sensitive designs.

Called the National Environmental Technology Strategy, the plan calls for promoting innovation, cutting red tape, "reinventing" regulations, and improving availability of information. It also seeks to shift emphasis away from costly cleanups and toward long-term pollution prevention.

By November, federal, state, and local governments are to join with private industry to update R&D priorities and demonstrate "green" technologies. A three-year goal: establishing a "market-based" process for verifying the technologies.

As part of the program, the U.S. government will let American companies use federal sites to test and demonstrate the effectiveness of environmental innovations.

Parts of the Strategy already are underway. The federal government recently launched a Rapid Commercialization Initiative to stimulate business use of environmental know-how. Over the coming year, program officials expect to commercialize ten technologies.

Also, the U.S. Environmental Protection Agency now runs a voluntary program called Design for the Environment. It encourages businesses to incorporate environmental considerations into designs.

"We will move from discrete technologies tackling particular problems to the integrated design of large systems," according to the Strategy report, recently unveiled by Vice President Al Gore.

One long-term goal: holding down use of resources in the design of every product and manufacturing process. As work unfolds, government planners believe, radically new products will feature longevity and "reusability." And, information needed for critical design tradeoffs will be widely available.

"In the end," the Strategy document predicts, "environmental technologies will virtually disappear as distinct pieces of hardware, and environmental concerns will become more fully integrated in the fundamental design of all products and processes."

Plasma source ion implantation (PSII)-a cleaner, longer-lasting alternative to chrome plating-is an environmental offspring of defense research at Los Alamos National Laboratory.

-Walt Wingo, Washington Editor


System pinpoints biopsy needles

Princeton, NJ-Five million people undergo needle biopsies each year in the United States, and some patients must retake the test due to inaccurate results the first time around. These needle biopsies are often performed through an image-guided method that uses ultrasound technology. The problem with ultra-sound biopsies: It is often difficult to see the needle in the ultrasound image. Now EchoCath, Inc., Princeton, NJ, has developed a system that eliminates this problem.

The ColorMark(TM) system features a small device that, when attached to a biopsy needle, causes the needle to vibrate at almost undetectable levels. The device is used with a color-flow Doppler ultrasonic system that projects an all-black-and-white image, with the exception of anything that moves; those portions appear in color.

Because the ultrasound machine can detect the slightest movement, the needle's vibrations provide a colored image of the needle on the screen. This makes the needle clearly visible to the technician.

The most critical part of the ColorMark system is the driver, which causes the needle to vibrate. Engineers used Algor software to determine the optimal size and shape for the driver, to enable it to vibrate at a number of natural frequencies to accommodate various needle sizes.

Engineers also needed to determine the natural frequencies at which a variety of needle sizes would vibrate. Using Algor's Beam Design Editor, engineers examined different needle sizes with various driving forces imposed on them. "The information about the driver and needle frequencies enabled us to develop the optimal design for the system," says Bayard Gardineer, vice president of engineering at EchoCath. "Overall, we built dozens of models to create the system. But with Algor software we avoided building hundreds more."

Algor software enabled engineers at EchoCath to locate natural frequencies without having to build new models for every design change. Shown is the modal analysis of the clip of the ColorMark system.


Workstation makers boost graphics power, speed

Newton, MA- Hewlett-Packard has unveiled its next-generation of graphics workstations, featuring several hardware innovations that offer up to a three-fold boost in performance.

"I was pretty impressed," says Peter Lowber, senior analyst at Datapro, Lexington, MA. "The graphics are outstanding. HP has really leapfrogged."

Sun Microsystems, meanwhile, announced a new system that roughly doubled the company's desktop graphics performance. "The SPARCstation 20TurboZX has performed beyond our expectations in tests with the I-DEAS Master Series," according to William Carrelli at SDRC.

HP's new "J-class" workstations incorporate a redesigned system bus running up to three times faster than its predecessor. Engineers speeded up throughput via custom-designed silicon, including a chip to perform texture-mapping. There are 13 patents pending on the new system, HP officials say.

The chip for hardware texture-mapping dramatically increases speed for such graphics, the company says. Texture mapping is a technique for photo-realistic graphics, and is extremely compute-intensive. HP's new design features texture caching, so if memory overflows while texture-mapping a large image, the cache allows the system to operate at almost full speed. Conventional systems rely on software texture-mapping when the memory is full, slowing the system.

"We believe this is going to change the face of design applications," says HP's Pete Dubler-hastening the day when engineers can model full systems, such as complete autos and airplanes, with realistic graphics on their desktops.

The VisualEyes-48 graphics accelerator, at $16,000, scales up to 235 PLFsurf 93, a measure of 3-D graphics speed developed by the National Computer Graphics Association. "That's absolutely unprecedented in the industry," claims Mark Pacelle at Hewlett Packard. HP's design also substantially increases graphics speeds if the CPU is upgraded to a faster model. Prices for the workstations start at $32,775. Engineers using HCRX-8Z and HCRX-24 graphics can upgrade to new VisualEyes 3D graphics accelerators for a $1,500 price differential.

Sun's SPARCstation 20TurboZX workstations prices range from $32,795 to $41,495, depending on CPU and configuration.


Plastics address semiconductor ESD, heat, and chemicals

Reading, PA-The Polymer Corp. has introduced five new plastic materials designed especially for use in the semiconductor manufacturing process. The materials are said to offer superior chemical and wear resistance, dimensional stability, and high purity.

"With this range of high-performance plastics, design engineers can select a material that best meets a design involving the use of semiconductor processing and test equipment," says Fred Sanford, Polymer Corp. industry manager. The materials, all of which come in rod, bar, and plate stock shapes, include:

Semitron(TM) ESD 225, ESD 410, and ESD 500 electrostatic dissipative polymeric materials.

  • Duratron(TM), a high-heat-resistant, high-purity polyimide material.

  • Celazole(R) polybenzimidazole, said to be the highest heat-resistant plastic currently available on the market.

Traditional technologies for achieving static dissipative performance in plastics include: conductive reinforcement (steel and carbon fiber and carbon black), hygroscopic salts, special antistats, and chemical enhancement. However, conductive reinforcements can prove unreliable, since microarcing can occur when a static charge exceeds 500V, creating a permanent conductive path to ground. On the other hand, hygroscopic salts fail to provide a permanent solution, since they rely on moisture to be effective. And, topical antistats tend to wear away over time.

Chemical enhancement provides the only reliable permanent solution for producing static dissipative plastics, according to Sanford. Both Semitron ESD 225 and ESD 500 are "permanently ESD [electro-statically dissipated] and not susceptible to microarcing," he adds. Typical uses include IC inspection station material for making wafer combs, flat finders, and vacuum wand tips.

Duratron HP can be machined to form dimensionally stable, structural parts for continuous use at temperatures up to 580F. The material also exhibits low outgassing based on the ASTM E595 test. And it resists aromatic hydrocarbons, acids, and bases. Typical uses include "fingers" for handling hot glass and insulators and connectors.

Celazole PBI has a continuous-use temperature of 750F, a heat-deflection temperature of 800F, and can be exposed short-term to 1,000F. Other major properties include: 50,000-psi compressive strength, flexural modulus of 950 kpsi, and a low coefficeint of thermal expansion.

Insulating blocks made from Polymer Corp.'s Semitron ESD 500 plate dissipate static electricity in test-handling equipment.


3-D modeling helps design advanced spinal implants

Cleveland, OH-Thousands of people report back problems to their physicians annually. Not all require surgery, but when they do, there is little room for error. AcroMed, manufacturer of spinal implants, uses 3-D modeling to keep the risk of error to a bare minimum.

Using both AutoCAD design and SDRC's I-DEAS solid modeling software, engineering service's Frank Byers and his colleagues create 3-D images of discs and surgical devices.

"Recently," says Byers, "I-DEAS helped me completely redesign an artificial vertebral disc." Byers then uploaded the solid model files to an outside stereolithography service to generate a prototype part. "It was a three-day turnaround time between conceptual design and part-in-hand."

Byers notes that 3-D computer models prove to be the best visualization tool when physicians visit AcroMed.

"The 3-D solid model serves as an accurate representation of the actual part," Byers says. "Doctors generally do not understand 2-D drawings."

Byers says I-DEAS also assists in defining part details and contours-a critical consideration.


Parametric Technology buys Rasna Corp.

Waltham, MA-Parametric Technology Corp., developer of the Pro/ENGINEER family of mechanical CAD products, has purchased Rasna Corp. of San Jose, CA, developer of the MECHANICA family of analysis products. Pending approval of Rasna's stockholders, the sale will be finalized by mid-August.

The acquisition brings together two of the most dynamic players in the computer-aided engineering industry. International Data Corp. rates PTC as the top mechanical CAD/CAM vendor in terms of software revenue. Inc. magazine last year rated Rasna as the third fastest-growing private company in the U.S. But, there are differences between the companies, as the Gartner Group's Dave Burdick points out. "Rasna is technology centric, and PTC is sales centric, with the lowest R&D expenditures vs sales in the industry," he says. Still, he says, there are synergies that make the merger good for the companies and their customers.

Primary among the synergies: Rasna's analysis software fills out PTC's product offerings. The integration will make it easier for engineers to do the form, fit, and function of design in one package, says Rasna President David Pidwell. Adds PTC Chairman Steven Walske, the combination is critical to PTC's plans "to architecture the industry's first digital design automation toolset encompassing product concept through manufacturing."

I-DEAS can illustrate the placement of artificial discs between spinal vertebrae.


CAD delivers variable-pitch propeller

Spokane, WA-Thanks to CAD and 13 years of engineering perseverance, recreational boat owners can replace their fixed-pitch propellers with "two-speed", auto-shifting models. Produced by Aerostar Marine, the Power Pitch and Switch Blade Pro series of props increases off-the-line acceleration by 30 to 40% without sacrificing top speed.

The propeller's secret lies in a patented shifting mechanism that combines inertial weights, springs, and hydrodynamic forces to change blade-pitch by six inches. Out of the hole, the center of pressure (CP) on each blade lies forward of the blade shank, producing a moment about the shank. In this situation, an over-center mechanism locks the blades into the low-pitch position.

As the boat increases speed, the CP shifts aft until it nearly aligns with the shank. This action releases the over-center lock and allows the propeller to shift into the high-pitch configuration. "It senses the loads on the blade and changes gears like an automatic transmission in a car," says Steve Speer, Aerostar Marine's president.

The shift point varies dynamically with propeller speed and loading; if the boat planes early, the prop shifts early as well. Originally, engineers toyed with creating an infinitely variable propeller. But variable, unpredictable loading produced uncontrollable flutter, and they switched to the two-speed design.

To expedite the design process, engineers turned to Intergraph's (Huntsville, AL) EMS computer-aided engineering system. Its 3-D solid- modeling allowed them to lay out aerodynamic sections in a plane, and then wrap sections to a radius to create the blades.

EMS let engineers prepare patent drawings, fit the propeller's 80 some-odd parts together on screen, and send CAD data to vendors. "We needed a package that could do a variety of functions including mechanism analysis, finite-element analysis, and also be able to get into NC machining of the blades," says Speer. Intergraph emerged as Aerostar's choice after two years of in-depth evaluation of CAD packages.

Speer drew inspiration for the variable-pitch propellers from his firm's experience with aircraft design. "They are almost a standard with aircraft," he says. "We wondered why not with boats?"

-Mark A. Gottschalk, Western Technical Editor


Software trims gas-spring design time

Leicester, UK-Engineers at Camloc Products are using a PC-based statics an-alysis software package from Saltire Software, Beaverton, OR, to quickly simulate mechanical designs that use gas springs.

Analytixa software combines a parametric sketching engine with mechanical simulation and analysis, and can be used for a variety of mechanical designs. Embedded equations allow the software to perform kinematic, inverse dynamic, and force analyses.

For example, with gas-spring design, the geometry and applied load vary considerably based on the application, explains Camloc Project Engineer Andy Bools. "So rather than doing laborious hand calculations to get the optimum geometry, rotation, and spring force, we set up the application details in Analytix, and from there we can quite simply modify mounting positions or applied loads without having to start from scratch."

Camloc engineers have used the package to simulate automotive tailgates, tanning booths, and other applications. "It lets us show the customer how well the spring would match their requirements before they go to the expense of testing," says Bools.

The software saves time during concept trials, he adds, "but the biggest benefit is that you get away from trial-and-error before tests. Using Analytix, we can match spring performance with the customer's requirements. We're getting 95% of the design on the first go."

Other users have applied the software to the design of hinges, folding seats, hydraulic actuators, linkages, conveyor systems, and printed-circuit-board assembly machines.

t0> Analytix starts at $895; a combination of that package and the Dynamixa option for forward dynamic simulations such as trajectories or impacts costs $1,350.

Analytix software simulates movement for mechancial design analysis.


CAE tool aids chip-holder design

Dallas, TX-When Texas Instruments' Corporate Research and Development Division was charged with designing a semiconductor sample holder that could withstand liquid-helium temperatures, TI engineers called on ANVIL-500(R) CADD/CAM/CAE software from Manufacturing and Consulting Services (MCS) of Scottsdale, AZ.

The customer, another TI division, needed the holder for the interior chamber of an analytical spectrometer. In addition to withstanding -272C, the product had to fit within a specified cubic area and be of low mass.

Tool- and instrument-builder Craig Fischer received the preliminary design on disk. He imported AutoCAD geometry into ANVIL-500, which he says easily translates DXF files. The TI Model Shop team used the design and drafting portions of ANVIL-5000 to build a 3-D wireframe model of the sample holder.

Once he was satisfied with the model, Fischer brought the customer in to view it on the shop's workstation. "I made changes on the fly using the software while the customer was there watching." Together, they could examine the design on screen and see immediate results or get answers to "what-if" scenarios.

When Fischer completed the prototype sample holder, it weighed less than one pound and was 6.25 inches in diameter. After design approval, he broke the finished design into components so he could generate individual drawings for its assembly. Fischer gave the drawings to other shop workers to begin CAM procedures for making the part. The Tool Shop used ANVIL-500 again to create the tool paths necessary for manufacturing.

Fischer credits NCPost, a new post-processor, with making it simple for machinists to create customized code when needed instead of having to hire someone to write the code for them. "I find that being able to go directly from design to NC without having to convert anything helps tremendously and saves time," Fischer says. "I don't have time to be redrawing things because of a conversion problem."

Washington Beat

Washington Beat

Report cites major shifts affecting engineers' jobs

New engineers must prepare to be flexible in their work and expect to change positions and even careers more than any previous generation. So concludes a study by a committee of the National Academies of Science and Engineering. The report catalogs a profusion of changes that are influencing engineering careers. It points to the rise of new technologies and industries and to stiffer international competition. Other factors: concern over environmental decline and new challenges to national security. The end of the Cold War and tougher spending constraints in government and industry further disrupt demands for engineers. The job market, the study continues, has become "more interdisciplinary, collaborative, and global." It requires people who are "adaptable and flexible as well as technically proficient." The panel recommends that colleges discourage students from over-specialization. Instead, they should provide undergraduates with options that allow them to gain a wider variety of skills. The study says graduate education, meanwhile, should focus more on the needs of those whose careers will not be mainly in research.


Passive heat exchanger undergoes zero-gravity tests in orbit

A passive thermal device is being tested aboard the FAISAT-1 commercial satellite. Swales, Inc. of Lanham, MD, developed the heat exchanger, which features a capillary pumped loop (CPL). The Ballistic Missile Defense Organization sponsored original research on the CPL for space-based applications. The system uses condensation and evaporation to draw heat away from the satellite's electronic parts. Swales' cryogenic CPL ends the need for heavier mechanical devices that are power-hungry and failure-prone. The purpose of the FAISAT-1 excursion is to prove that zero-gravity operations of a thermal bus suit small satellites. The company hopes designers also find the device useful for cooling electronics and for controlling temperatures in protective wear.


New private center could replace Office of Technology Assessment

A new organization aims to help people on Capitol Hill understand current issues in technology and science. The American Association for the Advancement of Science formed the group, called the Center for Science, Technology, and Congress. The Center plans to hold off-the-record briefings for congressional staff, produce updates on issues, and publish a monthly bulletin. Some functions of the Center overlap those of the Office of Technology Assessment (OTA), an arm of Congress. The fate of OTA has been in limbo since Republicans captured leadership on the Hill. Robert Walker (R, PA), chairman of the House Science Committee, told Design News that OTA takes 18 to 24 months to complete its studies. That, he said, is too long for use by legislators. Several Representatives have suggested that the science association could do OTA's job better at less cost.


Federal aviation agency opts for off-the-shelf systems

In a fight for its life, the Federal Aviation Administration (FAA) is looking to the outside for help in modernizing its operations. George L. Donohue, FAA's associate administrator for research and acquisitions, described the new policy at a congressional hearing. Said Donohue: "We are getting away from...an outdated view that if the FAA doesn't design it and develop it from scratch down to the last detail, it won't serve our purposes." Instead, he added, FAA is moving toward "commercial off-the-shelf, non-developmental items" that the agency can adapt to fit its needs. The FAA is among federal agencies being considered for privatization. Its critics say the agency has made little progress in streamlining the nation's air traffic control system, though it has spent billions of dollars for that purpose over the past 14 years. Donohue, who joined FAA last year, agreed that management of FAA's Research, Engineering, and Development programs has been "out of step" with rapidly changing technology. FAA now is reviewing outside technologies for many of its projects. Among them: windshear detection and avoidance, systems to stop aircraft that overshoot runways, and ways to foil terrorists.


Books help you wend your way through the Internet maze

Having trouble getting to those lodes of engineering information on the Internet? Two new books introduced in Washington, DC, could help. One is the fifth edition of "The Internet Passport," a guide to on-line journals, newsletters, books, libraries and databases. NorthWestNet, an Internet link, compiled the 667-page manual. The other is "Hands-On Mosaic: A Tutorial for Windows(R) Users." Written by David Sachs and Henry Stair, the book describes how to use Mosaic(R), a multimedia-rich interface to Internet. Included is a disk with copies of Internet aids FTP, Telnet, Mail, and Ping. Both books are publications of Prentice Hall PTR of Englewood Cliffs, NJ.

Bearing rolls three designs into one

Bearing rolls three designs into one

Goteborg, Sweden-Each of today's main bearing types offers special qualities unique to the application at hand. For example:

Needle roller bearings are compact, but, unfortunately, they cannot function when the shaft is misaligned.

Spherical roller bearings accommodate misalignments and heavy loads, but are not able to handle axial displacement without causing friction.

  • Cylindrical roller bearings allow axial shaft displacement, but cannot function when misaligned.

A new design from SKF combines the key advantages of all three bearing types. Called CARB(TM), for Compact Aligning Roller Bearing, the design offers low friction and a high radial load-carrying capability. At the same time, it can accommodate misalignments and axial displacement of the shaft.

Key to CARB's success are its long, barrel-shaped rollers. A profile radius much larger than that of rollers in single- and double-row spherical roller bearings reduces friction without sacrificing the bearing's self-aligning capability. Additionally, locating the center of curvature of the outer ring raceway beyond the bearing axis allows: a wider bearing for favorable load distribution; greater possible axial displacement per given radial clearance; and designs with low section height. The only tradeoff is a reduction in axial load capability.

Field trials at the Braviken paper mill, just outside Norrkvping, Sweden, confirm the bearing's advantages. Installed in the plant's drying cylinders, the bearings must accommodate as much as 10 mm of thermal expansion in the thin-walled hollow cylinders.

SKF reports that the first CARB bearings will be available in outside diameters ranging from 310 to 500 mm.

Additional details, Europe...Contact SKF Group Public Affairs, S-415 50 Goteborg, Sweden, Tel: +46 31 372005, FAX: +46 31 372832.

Additional details, U.S...Contact SKF USA Inc., Box 1507, King of Prussia, PA 19406-0907, Tel: (610) 962-4300.