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Articles from 2003 In January

Designing with cast aluminum plate

Designing with cast aluminum plate

Aluminum plate is specified for countless uses that benefit from the inherent properties of the metal itself. Aluminum's reduced weight, easy workability and thermal/electrical conductivity contribute to the performance of many products. With its versatility and high speed for a variety of machining operations, aluminum tooling plate has advantages that make it a popular choice for shaping intricate components.

When selecting aluminum tooling plate for applications where dimensional control is critical, the design engineer must be confident of precise tolerances and dimensional stability. Fixtures and quality control equipment illustrate the need for close tolerances - in such equipment, components may require controlled thickness and flatness to serve as the base for a tool or a measuring device. This type of portable fixture is found in industries ranging from aircraft to automotive, computers to electronics, and printing equipment to food processing machinery. The second consideration, dimensional stability, is an important factor in parts that are machined by removing extensive levels of metal (as much as 85%). Dimensional stability must be considered both before and after processing, as well as in components subject to wide temperature variations.

To hold critical dimensional tolerances, important distinctions arise between cast aluminum tooling plate and its wrought counterpart (an aluminum plate product subjected to mechanical working by extruding, rolling, forging or other processes). Wrought aluminum plate is adequate for many purposes, but does not offer the tolerance control or stress relieved properties that are available in cast aluminum plate. As a result, extensively machined wrought aluminum plate products will not hold machined tolerances and tend to distort out of flat. Cast aluminum tooling plate offers much better dimensional stability.

Cast aluminum tooling plate is not new. In the 1950s, development of large commercial jet aircraft such as the Boeing 707 and the DC-8 required new levels of tooling accuracy and stability. Materials commonly used for tooling at that time included rolled steel, rolled aluminum, plastic, wood and masonite. None of these possessed the stability to assure tooling accuracy within wide temperature ranges for the assembly of giant fuselage and wing sections. Attention turned to aluminum. Its lightweight, non-pyrotechnic properties, workability and ease of machining led to initial trials using wrought aluminum plate as tooling. These failed, as there was no method for initially flattening the plate and the wrought material lacked dimensional stability.

In attempted improvements to wrought plate manufacture, several aluminum companies tried stretching wrought plate as a way of flattening and relieving thermal stress. Although such products were subjected to artificial aging treatments (typically between 250 and 350 degrees F), the procedure did not result in complete stress reduction, and dimensional stability remained inferior to that available in the cast process.

The first efforts to cast an aluminum plate product relied on the open mold method. In this process, as solidification moves through the molten metal, impurities, entrapped gas and porosity are pushed ahead of the liquid-to-solid transition zone. Heat is removed unevenly and only in one direction, so the quality of one plate surface is noticeably inferior to that of the opposite surface. The varying surface quality and non-uniform thermal stress cause distortion during machining.

Subsequent approaches to cast plate manufacture utilized vertical direct chill casting (pouring molten metal through a water-cooled collar to produce an ingot 24 or more inches thick). The ingot was stress-relieved after casting (to relieve the high stress levels induced by casting), saw cut longitudinally to required plate thickness, and then surface machined to finished dimensions. Quality improved, overcoming earlier problems of inclusions, internal soundness and grain size. However, saw cutting and machining to finished dimensions (after thermal stress relief) still resulted in a dimensional stability problem.

After considerable research, in the early 1960s Alcoa began production of a cast plate product using a DC horizontal casting method to produce a relatively thin ingot. The process was a significant improvement in equalizing the solidification process. Each thickness was individually cast and then surface machined (milled) to reach finish gauge. Currently, this product is known as Alca Plus(TM) and remains a good quality aluminum plate for general use.

Ultimately, it was a process pioneered by Hunter Engineering that led to today's most advanced cast aluminum plate. The company, a forerunner of Alumax, developed a horizontal, continuous caster to produce individual plate thicknesses. Alumax refined the technology to bring dimensional control and stability to the next level. The original product (named CC-70) has evolved to become the state-of-the-art material known as Mic-6(R) Precision Machined Cast Aluminum Plate. Alcoa, which acquired Alumax in 1998, now produces and markets Mic-6(R) Precision Machined Cast Aluminum Plate at its Mill Products facility in Lancaster, Pennsylvania.

The Mic-6(R) manufacturing technology involves a patented continuous casting technique that allows precise casting to near net thickness - the "as-cast" thickness is only a few thousands of an inch greater than the final plate thickness. Using a continuous flow of molten aluminum, casting speed and the rate of solidification are tightly controlled. A spinning nozzle inert filtration (SNIF) unit provides additional filtration and degassing, virtually eliminating internal defects. Proprietary equipment removes heat from both plate surfaces at a carefully balanced rate so thermal gradients are stabilized. As a result, grain size and distribution are identical on both plate surfaces!

This unique casting process gives Mic-6(R) a granular structure that resembles a honeycomb (seeFigure 1). In the solidification process, aluminum (which has a higher melting point than the alloying ingredients) forms the cell core with alloy elements concentrated between the cells. This segregation of low and high melting point compositions imparts characteristics that make Mic-6(R) highly machineable, producing small, uniform chips in a variety of high speed operations.

After casting, the Mic-6(R) plate is subjected to thermal treatment in excess of 700 degrees F for up to 10 hours. The resulting product is fully stress relieved (fully annealed), eliminating stresses that developed during casting as well as any heat-treating effects that may have occurred during or after solidification. The material is "dead soft", comparable to the "O" temper designation in wrought aluminum.

These steps result in a significant design benefit for Mic-6(R)...there is no decrease in mechanical properties when the plate is exposed to elevated temperatures. This is true for both extended periods of high temperature and cyclical exposure (even an infinite number of thermal cycles). Once the Mic-6(R) plate is returned to room temperature, its tensile properties are the same as they were prior to exposure. There is no over-aging, which occurs in solution heat-treated plate, or the partial annealing that is characteristic of strain-hardened material. Accordingly, Mic-6(R) is recommended for applications where high temperature conditions would be a problem for wrought aluminum tempers.

Surface machining to final gauge and a precision surface finish is the final step in manufacturing Mic-6(R). The product's process technology minimizes the amount of surface removal required to less than one-tenth of an inch per side. In other cast plate processes (such as open mold, DC ingot slabbing and thin DC casting), it is necessary to remove as much as 50% or more of the material by surface milling. The limited surface machining of Mic-6(R) minimizes both friction heat and the effects of tension and compression, which contribute to metal stress and cause distortion in other plate products. In many applications, Mic-6(R)'s precision machined surface finish of less than 20 micro-inches eliminates the need for downsteam milling or surface grinding.

Mic-6(R) Precision Machined Cast Aluminum Plate undergoes 100% inspection. Laser equipment unique in the industry is used to individually check each plate to verify that it is within specification for flatness and thickness. Finally, a strippable PVC film is applied to one or both sides (whichever is specified) for protection during handling and intermediate processing, and the plate is securely carton packed for shipment.

The entire Mic-6(R) manufacturing process was designed and perfected to minimize internal material stress. Stability is the product's defining characteristic, allowing for downstream processing while maintaining precise control of tolerances and dimensionality. That offers the design engineer a flat, stable aluminum plate product that is cast to near net thickness, finished on both sides, and readily machineable with precision results on a full range of high speed automatic equipment.

Uses for Mic-6(R) Precision Machined Cast Aluminum Plate span nearly every industry that requires flat, stable aluminum plate for general tooling and precision components. A partial list of markets where Mic-6(R) has been an unparalleled success includes:

Aircraft Office Machinery

Appliance Ordnance

Automotive Packaging Machinery

Building Materials Pharmaceuticals

Chip and Circuit Printers Plastics

Data Processing Equipment Printing Machinery

Electronics Robotics

Food Processing Machinery Textile Manufacturing

Medical Instrumentation

In one case study, a manufacturer of medical instruments for blood analysis required a base plate with precise thickness and flatness tolerances. The tolerance standards had to be met both after the plate was sawed to custom length/width by the processing distributor and after 50% metal removal during machining by a contract processor. The attributes of Mic-6(R) made it an obvious choice.

In another use, a leading manufacturer of label printers converted from steel plate to Mic-6(R) for its side frames. The printing machinery could range to 120 feet in length, so dimensional stability was essential to the parallelism needed for operating accuracy. In addition to its unmatched stability, the choice of Mic-6(R) resulted in significant weight reduction, improved material handling and a dramatic reduction in material processing times. For over 20 years in this application, Mic-6(R) has proven virtually defect free.

Mic-6(R) Precision Machined Cast Aluminum Plate is found worldwide in demanding applications, specified for use as a tooling material and in dies, base plates, jigs, fixtures, molds, patterns, framing and more. For the design engineer, Mic-6(R) represents the opportunity to create new products and enhance product performance, confident that the specified material will deliver precise dimensional control.

Leighton M. Cooper is Marketing Manager of Common Alloy and Heavy Gauge Foil for Alcoa Mill Products in Lancaster, Pennsylvania. He holds a Bachelor of Science degree in Metallurgical Engineering from Iowa State University and an MBA from the University of Iowa.



Fingerprint slide

Ultra-small for wireless devices

TruePrint(TM)-based biometric fingerprint slide sensor is reportedly ultra-small and uses little power, and is available for PDAs and wireless devices. The EntrePad(TM) AES2500 is billed as the world's most advanced sensor, and is designed for OEMs to provide security and password replacement. The technology allows fingerprints to be read below the surface of the skin, reportedly eliminating most recognition failures due to dirt, dry skin or excessive moisture. AuthenTec Inc., Enter 577

Sub-mini relay

Standard and latching coil

The T-series low-profile DPDT relay with a standard and latching coil reportedly meets FCC part 68's 1500V surge. UL and CSA listed for high quality and safety, they offer a mechanical life of 100 million cycles. DPDT relays measure 5 x 9 x14 mm. T-series switches 30W dc, 62.5V ac at 125V dc or ac at 1A. Hasco Components Enter 578

Fixed-gain amplifiers

Wideband, low-noise op amps

High-performance fixed-gain amplifiers are manufactured using the company's BICOM-III process, reportedly the first complementary bipolar silicon-germanium process. The high-bandwidth, low-noise units operate from a single 3-5V power supply. The THS4302 high-speed op amp features a bandwidth of 2.4 GHz. Applications include wireless base stations, relay stations and other infrastructure equipment needing wider bandwidth packed in less space. Texas Instruments, Enter 579

Heating blankets

Provide controlled heat-ups

Environmental factors in heating applications require products with the ability to withstand chemicals, moisture and abuse. SRMU silicone rubber heating blankets come in a variety of sizes and shapes, resist radiation, and are a flexible solution for freeze protection, process temperature control and solids melting. As OEM or replacement parts, silicone blankets may be used in applications requiring rapid heat up, steady temperature maintenance and uniform heat distribution. OMEGA Engineering, Enter 580

Circuit breakers

High current-carrying ratings

The 8345 is a single-pole magnetic circuit breaker available in ratings up to 125A and measurements of 0.749 x 1.860 x 2.500 inches. The additional 25A reportedly makes the 8345 the highest current-carrying device available in its frame size. The circuit breaker is also UL 489A-compliant and available in two-, three-, and four-pole configurations. Applications include equipment, telecommunications, and plant control systems. E-T-A Circuit Breakers, Enter 581

Screw-clamp connector

High power, increased amps

The 7573 Series connector 10.16 mm pitch, screw-clamp PCB connector allows vertical wire entry through its 90 degrees wire-to-screw entry orientation. The series is UL-rated for up to 10A, 300V, and VDE rated for up to 59A, and 300V for wire sizes 22-8 AWG. Blocks are made of a polyamide 6.6 plastic housing and have marking tags for quick identification. Wieland Electric Inc., Enter 582

Wireless headset design

Create safer automotive devices

EtherMIND HS software for building hands-free wireless mobile Bluetooth(TM) headsets is available to automotive industry suppliers. Using EtherMIND HS, headsets connect wirelessly to an automobile's speaker system, provide full duplex audio, and act as the device's audio I/O mechanism. The headset eliminates all wires and gives users more mobility without compromising call privacy. MindTree Consulting Pvt. Enter 583


Design control of power use

PICmicro(R) FLASH microcontrollers feature nanoWatt technology, allowing flexible power managed solutions for system power consumption. These units feature electrically erasable cell process technology in an operating voltage of 2 to 5.5V, and are reportedly ideal for battery-managed applications. They are pin-and-code compatible with the company's 18-, 28-, and 40-pin products. Applications include smoke sensors, leak or gas detectors, hospital ID tags, security systems, portable devices, and glucose meters. Microchip Technology Inc., Enter 584

Software platform

Small, for rough applications

An industrial-distributed I/O line with a small, rugged form factor is reportedly suited for embedded control, data logging, and remote applications. Compact FieldPoint products extend the company's LabVIEW software to harsh environments for use by engineers and scientists needing advanced measurement and control capabilities in the field. This product family has 20 I/O modules and 3 intelligent controllers performing analog and discreet control to process signal generation, calculus, curve fitting, and statistics. National Instruments, Enter 585

Dc/ac inverter

Powers in-vehicle electrical devices

A 150W dc/ac inverter is available to power in-vehicle electrical devices, like televisions and VCRs. Reportedly the most powerful of its type, the inverter features 300W peak power, low battery warning buzzer, short-circuit protection, shock protection, low key-off current, optional driver-controlled on-off switches, and LED output reader. Applications include portable televisions, VCRs, personal computers and peripherals, and infotainment systems. Designed to meet OEM power and performance requirements, units reportedly help protect appliances from radio interference, electrical fire and other vehicle damage. Omron Automotive Electronics Enter 586

FPC connectors

Secure cable retention

Design engineers can make secure PCB connections in hand-held devices using 6298 Series connectors with a space-efficient, low profile of 0.9 mm. Units feature front-hinged actuators and connectors that lock flex cables into position, compensating for poor cable retention. Available in 3- or 4-position types, these 0.5 mm pitch connectors accept 0.2 mm flex circuits. With an operating temperature range of -25 to 85C, units are surface-mountable and compatible with automated assembly equipment. AVX Corp., Enter 587

Voltage care plan

Low uncertainty, downtime

A Direct Voltage Maintenance Program is available for this company's 732 series and 734A reference standards. This program meets increasing demands for accurate, on-site calibration at low cost and allows metrologists to conduct calibration procedures on standards while the company writes and maintains the data. Benefits include virtually zero down time, multiple standards support, optional product warranty coverage and special reports. Fluke Corp., Enter 588

Instrumentation modules

Channel-to-channel isolation

The DI-1000TC line of instrumentation modules is designed for use across all temperature-measurement applications including laboratories and heavy industry. Its channel-to-channel isolation feature is ideal for use in industrial applications that include the large common-mode voltages typical of grounded thermocouples. They also support synchronization of measurements among connected modules, guaranteeing simultaneous readings. Features include a sampling rate of 5 Hz, free PDA software, built-in open T/C detection and high accuracy. Dataq Instruments, Enter 589

Fiber optic sensor

For direct surface mounting

A miniature fiber optic sensor designed to be used without an enclosure does not require DIN-rail mounting and features a unique snap-mount bracket and an adhesive-mounting for location flexibility. Reportedly rugged, lightweight and low profile, the units have a plastic housing and IP67 environmental rating suited for mounting directly on machines. Designed for use with the company's stainless steel sheathed fiber, the system is less bulky than glass fiber optics. Features include visible light beam, manual adjustment, and 8-segment LED display. Banner Engineering Enter 590

Inverter driver ICs

Simplifies motor drive design

Appliance manufacturers using variable speed motors can reportedly save half the energy and use new features with the IR2136 family of three-phase, inverter-driver ICs. This series is designed to save energy in electronically driven home appliances like clothes washers and air conditioners, as well as light industrial and automotive motor drives. Features of the 600V ICs include COMS or LSTTL compatibility and 120mA/250mA output source/sink current. This IC uses cross-conduction prevention logic to eliminate short circuits and automatically clear over-current fault conditions. International Rectifier, Enter 591

Radio, I/O module

Used in harsh industrial environments

Designed to eliminate cable and conduit for analog and digital signals in harsh industrial environments, the MCR-RT-I/O-PLUS is available to add multiple changes of I/O to paired transceivers in combinations. Features include expandable I/O options, 600-1,000 ft indoor range with no line of sight, separately powered transmitter and receiver, and no wiring requirement. The system is reportedly maintenance-free, reliable, and offers quick installation compared to other systems. License-free and interference-free, it mounts in a DIN-rail mount housing with integrated bus connection for communications. Phoenix Contact, Enter 592

Rewind motors with no penalty

Rewind motors with no penalty

Worried about whether rewinding a motor will degrade its efficiency? Well rewind away. Findings from a study by the Electrical Apparatus Service Association conclude that motors can be rewound multiple times with no loss of efficiency, so long as it's done carefully and operators follow standard procedures. The study examined 50 to 300 hp electric motors with ratings of 1,800 and 3,600 rpm.

Silicon Power Device Challenges Relays

Silicon Power Device Challenges Relays

A new solid-state relay from Motorola is a cool operator-so cool, in fact, that it could be a formidable competitor for many electromagnetic relays. Unlike typical SSRs, which generate a lot of heat while passing large currents, the MC33982 silicon power switch stays cool to the touch even without a heat sink. That means that the already small (12x12x2 mm) device takes up much less space than a conventional relay while also providing an SSR's superior reliability and long life.

The key to the MC33982's cool operation is an unprecedented low source-to-drain on resistance (RDSon) of only 0.2 milliohms. Typically, this resistance for solid-state relays is at least tens of milliohms, which leads to significant power consumption and heat generation when the device conducts a current of more than a few amperes. Motorola uses its HDTMOS version of MOSFET technology to reduce this resistance, making the MC33982 useful in systems that require up to two KW of power. The device operates at 6 to 27 volts; it withstands continuous currents of about 60 amps and short-term currents of 150 amps.

To demonstrate the new SSR's current handling at the recent Convergence exhibit in Detroit, Motorola wired six of the devices in parallel and used them to replace a car's starter relay. Starting the car, says Kevin Anderson, Design and Applications Manager for Motorola Semiconductor's Analog Products Division, resulted in a current surge of over 750 A, or 125 A per SSR. The SSRs remained cool to the touch, although Anderson cautions that starter relays are not an intended application for the devices. The MC33982 could, however, serve functions such as operating car door locks, and Anderson notes that because of its very long life, it could go into a door panel without the need to design access for later replacement.

The device adds to its appeal with the ability to emulate a slow-blow fuse. You can program it to withstand a certain amount of current for a certain amount of time before it turns off, a useful feature in applications like lamp loads where there's a large inrush current, followed by a lower operating current. "A relay doesn't have that capability," Anderson says, "so you've got to size the relay for the maximum inrush current."

The MC33982 does cost more than an electromechanical relay. In fact, its starting price of $3.90 in large quantities is easily double some relay prices or even beyond. However, because the device's on-chip intelligence provides control and self-protection features that relays have to get from added components, Motorola claims that its overall system cost, not just device cost, is competitive with electromagnetic relays. The company also notes that life-cycle costs are lower for solid-state relays, because of longer lifetimes and the possibility of not having to design in physical accessibility for device replacement.

The MC33982's primary market is the automotive field, and Motorola claims that a major automobile manufacturer has already signed on to use the device in its 2006 models. Motorola isn't naming the customer, or any customers, however, nor will it say how the customer is applying the device.

Motorola is also targeting applications other than automotive for the new device. "Because it was designed for the automotive market," Anderson notes, "it goes into overvoltage protection at about 26 to 28 volts." That voltage, Anderson adds, makes the MC33982 well suited for 18-volt battery-powered hand tools and many 24-volt industrial applications. In addition, he says, Motorola is designing other versions.

Ask The Search Engineer

Ask The Search Engineer

Hey, Search Engineer: Do you know how a Slinky(R) is made? I need to make a similar part out of a brass material.-Richard in Los Angeles

Dear Richard: You're not working with Dean Kamen, are ya? Slinkies(R) are just flat wound springs, similar to retaining rings or wave springs made by companies like Smalley Steel Ring. They take a round wire (steel, bronze, and Be-Cu) and flatten it to size, then wind it. Maybe they'd be willing to make them for you out of bronze. For more details, the Slinky patent reveals all (US patent 2,415,012).

Mr. Search Engineer, Sir: I'm looking for an electronic fluid level sensor for my design, but my boss is pretty miserly. He's making me stick to a budget of less than five bucks. I was thinking of a float with a magnet attached to a shaft that activates a Hall sensor. But I'm concerned that I will have a corrosion problem, since the device will be subjected to unfiltered water and a max temperature of 100C.-Ron in Phoenix

Dear Ron: We describe this type of design problem as overconstrained. If you decide to go your route, you should take a look at any late-model automotive master cylinder. (You know those Scrooge-like auto engineers!) The float and the plastic tube the cylinder rides in do not corrode and are suitable for underhood temperatures (125C). Alternatively, Motorola makes an electric field imaging device that generates and detects loading of an electric field. This type of device could be used for liquid-level detection as long as the container is non-metallic. The liquid will change the electric field absorption for the electrodes. For finer resolution, analog outputs can be used to interpolate the level between the electrodes.

Greetings, Search Engineer: In one of our designs we use aluminum extrusions that are black anodized to obtain required optical characteristics. However, we find that the parts are fading to a brownish color after exposure to fluorescent light. How can we keep our black parts black?-K.K. in R&D

Dear K.K.: Have you talked to Mick Jagger? Because, bottom line, you got one big problem. Anodizing can fade extremely fast under fluorescent light. The solution to retain the color is to seal the parts. Keep in mind, though, that the seal is softer than the anodized surface. Check out more pointers at

Konichiwa, Search Engineer: I work for a manufacturer of plastic film capacitors and am working with the makers of digital tariff meters for auto rickshaws. They're having a problem with RF noise generated in the engine, which interferes with the functioning of a microprocessor in the meter. What capacitor should be used for suppressing the noise?-Tom in Tokyo

Dear Tom: You, me, we all got EMI problems! Your best bet is to attenuate the RF noise at the source. Try using resistor suppression ignition wires and/or resistor spark plugs in the engine.

Got a question for The Search Engineer? Send them to[email protected]. Personal replies are out of the question, pal.

Virtual Instruments Find Their Niche

Virtual Instruments Find Their Niche

Can you describe the difference between bench instruments and virtual instruments? If not, you're not alone! It gets more and more difficult to distinguish between the two. Virtual instruments, born in the 1970s, let you add functions as you need them, they provide sophisticated tools so users can program complex tasks, and they analyze data. Bench instruments, around much longer, are able to do many of the same things. Sophisticated instruments come with built-in PCs, run standard software, and let users quickly configure tests. And both types of instruments provide Ethernet connections that simplify communications with remote PCs.

Over the years, engineers have found that both bench instruments and virtual instruments play useful roles in product development, all the way from R&D labs to production test. So when should you use which?

Some engineers still think bench instruments are easier and faster to set up and use. But, the software and hardware in today's virtual instruments are burying the reputation this class of tool has had for being difficult to use. Now, virtual instruments are about as easy to use as bench instruments--and they make comparable measurements.

Virtual instruments serve particularly well when engineers must measure signals from many sensors, and when they need to change instrument configurations to accommodate more analog inputs or digital outputs, for example, and when they need to run complicated sequences of tests. Lots of extra channels can't be added to a bench oscilloscope or signal generator. Usually a bench instrument performs one task very well, but in most cases, it can't take on added tasks such as digital I/O and motion control the way virtual-instrument cards can.

Virtual instruments prove valuable when an application requires the acquisition of a lot of data for later analysis, such as a mechanical assembly that's undergoing lengthy stress tests that involve measuring and analyzing signals from hundreds of strain gauges. It's unlikely a stand-alone instrument can take all these readings, store them, and then run a program to produce a test report. But virtual instruments handle that sort of application very well. Need more inputs? Add a card. Update the test sequence? Engineers need to simply change the test software.

Speedy Shortcut: when engineers don't have a complete system available for testing, they simulate missing parts with hardware and software. This sort of "hardware in the loop" configuration can save time and money, although it requires a careful analysis of the characteristics.

On the other hand, if engineers must measure only a few signals, say during development of a new motor controller, they'll make many tests to quickly home in on signals of interest, and then move on to test other parts of the controller. In this type of situation, they may prefer a bench oscilloscope with manual front-panel controls.

After developing a circuit or assembly, engineers must validate that the design will work under actual operating conditions. But during validation testing, some parts of the overall system that relies on the circuit may not yet exist. In such a case, the engineers may design other equipment to simulate the missing pieces. During development of a navigation controller, for example, it's unlikely a company will actually supply a complete aircraft on which to test the controller's operation.

Instead, the design engineers must simulate actuator motors and use instruments to produce temperature, speed, location, and other data for the controller's inputs. In most cases, virtual instruments offer the only practical means to simulate these signal sources and make a controller "think" it has a real aircraft under its control. Engineers call this type of setup "hard-ware in the loop" because electronic instruments exist in the control or feedback loop to simulate actual motor and sensor operations. Of course, someone on the development team must program the virtual instruments to properly simulate the aircraft's characteristics.

Virtual instruments also excel on production lines. For the most part, production engineers want simple test systems they can set up and almost forget about. Such systems must provide a simple user interface-not a sea of knobs, switches, and displays-and a simple pass/fail indication for production workers. And engineers don't want to set up or configure dozens of individual instruments. Virtual instruments, combined with software provide this type of performance.

Virtual instruments let test engineers choose the capabilities they need from a variety of manufacturers, usually with the assurance that equipment from different sources will "plug and play." The sophisticated software that supports virtual instruments also lets production managers adapt test systems to changing needs, develop several test sequences for different products, and analyze data to produce quality-control reports. And because virtual instruments provide a great deal of flexibility, production engineers can quickly expand test systems to include provisions for motion control, machine vision, and feedback of measurement data to production equipment.

Bottom line: Engineers can endlessly debate the virtues of each instrument type, but plenty of applications exist for both instrument types. Ultimately, decisions come down to choosing the best instrument for a job and ensuring a long life for today's investment.

Charging Ahead

Charging Ahead

Name: Donald Robert Sadoway

Present position: John F. Elliott Professor of Materials Chemistry, Department of Materials Science Engineering, MIT, Cambridge, MA

Degrees: B.A.Sc., Engineering Science; M.A.Sc., Chemical Metallurgy; Ph.D., Chemical Metallurgy, University of Toronto

Area of research: The use of electrochemistry in the development of environmentally sound technologies for resource recovery and delivery.

Latest advance: My colleagues and I are working with a class of materials that has the potential to revolutionize battery technology. These materials are lithium polymers, which exhibit the mechanical properties of a solid and the electrical properties of a fluid. That seemingly irreconcilable combination is key, because in order to make a battery work you have to move ions around. Solids by definition do not move stuff around.

Impact on design engineers? The implications for product design are huge, because you can start thinking about a battery as a multi-layer laminate- along the lines of a potato chip bag. Today, engineers have to leave a big cavity for the battery in their designs. Imagine the space savings with a battery that can be folded up like a jelly-roll.

Why lithium polymer? In a battery, all you want is electrons, but you can't buy a bucket of them. Since you can only buy a bucket of atoms, you try to get the least amount of baggage per electron. Turns out lithium is the lightest practical conveyor of electrons. Hydrogen is lighter, but its energy density isn't all that great. The next lightest element is helium, but it's chemically inert.

Biggest challenge: Bringing the cost down. The polymers we use aren't expensive, but existing lithium ion batteries use a compound containing cobalt, which is extremely costly, as an active cathode. There is a considerable amount of research being done to find low-cost alternatives.

First battery-operated device owned: A transistor radio with a 9V battery.

Safe at Any Speed

Safe at Any Speed

Speed Thrills - Greg Hale, Disney's new chief of safety, stands tall on the new Primeval Whirl at Animal Kingdom in Orlando.

"We are currently experiencing technical difficulties on the Rock 'n' Roller Coaster. We will advise you on our progress."

"The engineers are here-it's going to be a wait," Emmett Peter, Director of Ride & Show Project Development at the Walt Disney World Resort tells me, pointing to a group of men in a huddle near the track as the message is broadcast. While waiting in line to ride Disney/MGM's newest roller coaster, I learned from Emmett that it starts out with a 1.3-G catapult-style launch, followed by an immediate double loop, a series of banked turns, and a barrel roll. Gulp. With the ride seemingly down for the count, I'm trying hard not to act visibly relieved. I didn't know that I would be expected to try out one of Disney's most extreme rides while reporting this article on how Disney's new Chief of Safety, Greg Hale, and the amusement park industry are working to ensure amusement park rides are safe. The interesting part of the whole story is that the engineers who design these rides face a basic dichotomy: Their whole goal is to make you feel like your life is in danger, yet have a design that is absolutely safe.

A little more than a year after the U.S. Consumer Product Safety Commission (CPSC) issued a much-disputed report indicating an increase in ride-related injuries and amidst much hype in the press about amusement park safety, Walt Disney Parks and Resorts appointed engineer Greg Hale to be its first Chief Safety Officer in June 2002.

Fast Lane - Disney/MGM's Rock'n'Roller Coaster -- one of the newest high-thrill rides -- goes form 0 to 60 mph in 2.8 seconds flat.

Safety has always been a hallmark of Disney, In fact, Hale, a 14-year veteran of the company, previously was responsible for operational safety. What's different about his new role is that he will oversee and facilitate the exchange of safety-related information and make sure that consistent standards are implemented across Disney parks worldwide. By sharing information, Disney hopes to institutionalize best safety practices at all properties.

What Hale does is sure to influence the rest of the industry, through his involvement with the American Society for Testing and Materials (ASTM). For the past decade and a half, he has been a member of the ASTM Committee F24, an independent standards-writing body that is responsible for developing amusement ride safety standards. Essentially a consensus process, it involves balancing different and often opposing interests among theme park operators, ride manufacturers, regulatory agencies, consumer advocates, and other interested parties.

Nothing polarizes people more than safety. Which means that Hale has his work cut out for him in a challenging job.

An unassuming man in his late forties with a preference for casual attire, Hale just may be the ideal person for the position. A self-proclaimed tinkerer who says he's always liked fixing things ("though I always had a few parts left over-it drove my mother crazy"), Hale graduated at the top of his class at the University of Mississippi with a degree in electrical engineering. He first worked in the petrochemical industry, then joined Olin Corp.'s Winchester Division in designing control systems for the manufacturing of explosives. Although of course designing the system was not as dangerous as operating it, the job nonetheless was a true trial by fire in safety management.

Getting hired at Disney in 1988 was more or less a fluke. Responding to an ad in the newspaper, Hale figured he probably wouldn't get the job, but hoped he might at least get a peek at some cool stuff behind the scenes. Since then, he's actually done all kinds of that cool stuff himself, all relating to attraction design, operation, and safety at Walt Disney World.

Works Well With Others

Engineers who have worked with Hale first remark on his technical acumen. "Greg's a very detail oriented engineer, a very smart guy," says Mike Withers, VP of Show/Ride Engineering for Walt Disney Imagineering.

"He's a creative thinker and a good engineer," says Dale Stafford, VP of Global Fastpass at Disney. Stafford once asked Greg for ideas on how to create additional capacity for the ride It's a Small World. "He didn't just have one idea like, 'Build a bigger boat.' He had something like six ideas," recalls Stafford. In fact, Hale is one of the inventors and patent holders on Disney's Fastpass system, which revolutionized the theme park industry by eliminating long lines at popular attractions.

Then they describe his uncanny skill for finding common ground in situations where none seems to exist. "Greg has this unique ability to be impartial and listen to the many sides of an issue, then come up with a solution that meets everyone's expectations," says Jim Seay, president of Premier Rides, a roller coaster manufacturer, and co-chairman of the ASTM F24 Design and Manufacturing Committee for Amusement Park Rides and Devices.

That skill has served Hale particularly well in his work with Seay and others to develop new technical standards for the amusement park industry. Because it is a consensus process, things can get laborious. Even a single negative vote (out of some 300 members) that's ruled persuasive requires re-balloting. Although the screaming and shouting are mostly things of the past, hundreds and hundreds of hours can go into debating the seemingly tiniest of points. All-nighters have been known to happen.

New Standards Raise Bar

Early this year, the ASTM F-24 World Standards Task Force expects to issue a new standard, known as the Standard Practice for the Design of Amusement Rides and Devices or Z9591Z. The result of literally tens of thousands of hours devoted to discussion and debate among technical experts from around the world, the 80-page document contains extremely detailed data on the design and manufacture of amusement park rides.

"In my opinion, we've really kicked things up a few notches in areas such as patron restraint," says Imagineering's Withers, chairman of the task force. "The standard now provides parameters that will help a ride designer determine the appropriate type of restraint based on the specific G-force loading."

The controversial issue of G-force limits is also for the first time being addressed in the new standard. There has been much debate in the research community on whether or not some high G-force roller coasters produce sufficient "head rotational acceleration" to cause brain in-juries. (The most recent development has been the release of a National Institute of Health sponsored study by the University of Pennsylvania that determined that the peak accelerations produced by some high thrill coasters-including the Rock 'n' Roller Coaster-were below the threshold required to produce brain injuries.) The standard will include upper limits (that vary by exposure time) for 3 axes (xyz) of G-force. This will be more comprehensive than the Euro Norm CEN standards for amusement park ride design, which themselves have been in development for over 12 years.

Mandated by law, the Euro standard served as an important reference for the F-24 task force. "Our goal in developing this standard was to incorporate the best input from around the world. After studying the Euro standard, we realized it represented a good framework that we could use to create elements of our standard in areas like the G-force limits," says Withers, who also represents the U.S. at CEN meetings in Europe as an unofficial member.

In a significant departure for the U.S.-based ASTM, representatives from countries like Russia, Italy, Germany, and Australia contributed to the new standard and shared information on best design practices. "The Australian standards have some excellent areas of focus with regards to operational safety, and we got a lot of good input from the Europeans on the design side," says Seay. "We also received some specific input from the Russians on G-forces. That's because many of the engineers now working in theme parks there came out of the Cosmonaut program."

Famous for being secretive, especially about an issue so sensitive as safety, Disney has assumed an unlikely leadership role in the development of standards. "Five years ago, the amusement park industry looked to organizations like Disney and Universal Studios to help them raise the bar," says Seay. "It would have been easy for these large companies to simply adopt the typical corporate attitude that there was nothing in it for them, but fortunately just the opposite occurred."

Disney literally opened its books to the ASTM organization, sharing the techniques and processes it uses to ensure that rides are designed to the highest standards. And several high-ranking engineers from Disney, including Greg Hale, Mike Withers, Emmett Peters, and Rich Langhorst, have spent hundreds of hours sharing their technical expertise with the task force. And that openness is likely to continue: For example, Disney engineers plan to take to the industry what they learn about different safety restraint systems they are currently testing. "We certainly want to help the whole industry where we can, and if we can do that by sharing information about safety issues and innovative technologies that we develop, we'll do that," says Hale.

Disney has a lot to contribute, says Dean Kamen, president of DEKA Research and developer of the Segway. "A while back, we did an impromptu, 'Let's get some of our engineers and some of your engineers together and do some benchmarking on how we go through failure mode analysis,'" recalls Kamen. "I'd have to say that we think we do a good job-we build Class 3 medical devices-but we were really impressed with how much detailed analysis that Disney does in their ride development efforts."

Who would seem to benefit the most from Disney's sharing of information are the smaller companies and mom-and-pop type parks that do not have the large engineering teams and expertise that bigger organizations bring to the table. Hale, however, stresses that everyone benefits. "What I think is important here is that we all came together in a non-competitive arena at ASTM and were able to share our best practices about things that we learned internally and to help ensure that those practices would be consistent across the industry. In the end, the goal of standards is to have everyone be able to look at them and know that if they follow them that the end product is a safe one."

"I think that the standards are more effective than anything else out there in their ability to influence good design," says Forensic Engineer Walter Laird. A specialist in amusement park ride accident investigation, Laird says that the ASTM standards are becoming better known and more widely accepted.

Not everyone, though, agrees that this community-based effort is enough. Representative Edward Markey of Massachusetts says that rides need more regulation, and has introduced a bill that would give the Consumer Products Safety Commission jurisdiction to conduct follow-up accident investigations at fixed-site amusement parks. It already does so at mobile (traveling) amusement parks.

"As well intentioned as the standards-setting people are, in the real world things happen and someone who is not beholden to the industry has to look at the information in order to make judgements and impose new safety requirements," says David Moulton, Chief of Staff for Representative Markey. "Do you think the airline industry, for example, would be safer without the NSTB? I don't think the airlines believe that it's not helpful having a vigorous safety regulator visit accident sites. In fact, the public expects it and their willingness to get on a plane the next day is that much greater."

Although the ASTM standards are voluntary and do not carry the same weight as a law, they routinely influence the regulatory environment. The standards for amusement ride design are being adopted by an ever-increasing number of states such as New Jersey, which in 2002 adopted G-force limits based on ASTM guidelines.

Many Facets of Safety

Sitting in an air-conditioned trailer on a back lot of Animal Kingdom, Hale reflected on the question of whether the new design standards will help to reduce or even eliminate amusement park ride accidents. "I think engineering standards are effective in helping to avoid design failures, but it's important to recognize that standards work hand-in-hand with good operation and maintenance practices, as well as guest education," he told me.

Non-contact stopping -- Popular in many transportation systems, block-zone safety systems are employed in roller coasters that run multiple trains on the same track. Each zone contains optical sensors that detect the presence and position of a train and brakes to stop a train in the event the previous one has not left the zone. The brakes on Disney's Rock'n'Roller Coaster consist of air-operated linear calipers that clamp onto a thin fin beneath the vehicle. When a zone is occupied, the brakes prior to the zone close. Zone lengths range from 20 to several hundred feet.

Ride operation and maintenance is a top priority at Disney. Cast members, for example, can only operate rides after undergoing attraction-specific training and have command of the ride's mechanics and operating procedures. To keep things running smoothly and avoid unplanned shutdowns, ride vehicles are routinely taken out of service for scheduled maintenance. Each night when the parks close, the maintenance team also inspects each attraction and will not authorize it for operation the next day if there are any maintenance issues that need attention. And of course, technicians and computer controls systems are monitoring ride operation con-tinuously, as I saw first-hand.

After getting a ride on the Rock 'n' Roller coaster after all, Emmett Peter took me behind the scenes to learn more about the earlier technical difficulty. Engineer Bill Whitley explained that the problem involved a one-second disagreement between two positioning sensors that make sure the ten-ton train properly engages with a linear synchronous motor-powered pusher cart. He was able to determine this by analyzing real-time data from the ride's PLCs, linear logic devices, and sensors.

Guest safety is a priority at Disney-and no wonder. According to a recent study by the Florida Department of Agriculture and Consumer Services, patron error accounted for approximately 76% of all amusement park ride accidents in Florida over the past three years.

In the summer of 2002, Disney rolled out a major campaign with the express purpose of building public awareness about safety. Over 10,000 new signs with safety instructions have been installed throughout the parks, and gates or fencing that cordons visitors off from active ride areas have been standardized. Hale also personally championed and wrote a section of the new standard on patron containment, which deals with fencing and guardrails.

In the end, the question is whether the industry's community-based effort to develop safety systems will be successful. How to measure success may be relatively odd, though, given that the only way to know the industry is doing a good job is when nothing happens.

Greg's Favorite Four
A lifelong lover of roller coasters, Disney's Chief of Safety Greg Hale has been known to sneak off during the day for a quick fix. Here are his top picks:
Ride Thrill Factor Greg's Review
Tower of Terror Drops 123 ft at top speed of 2,680 fpm; Accelerates at a rate 12X faster than typical elevator "Instead of a simple free-fall, it's an amazing 4,000 hp machine that provides a fantastic ride."

Rock 'n' Roller Coaster
Linear synchronous motors produce acceleration of 0 to 53 mph in less than 3 sec and includes three inversions "The 10-ton vehicle accelerates quicker than the fastest production car; the ride has a 4G vertical acceleration at end of first loop."

Test Track
Mile-long track features a 47-deg banked turn taken at over 60 mph "If you enjoyed playing with slot cars as a kid, this ride is a blast because you can actually ride one."

Features a three-degree freedom of motion base, mounted on a moving ride vehicle with four-wheel steering "The many axes of motion result in an amazing ride, not to mention a great way to chase dinosaurs!"

Simple. Not Stupid.

Simple. Not Stupid.

Once upon a time-about ten years ago, actually-visionary technologists dreamed of an easier way to apply sensors in industrial automation, process control, and test and measurement systems. Instead of numerous sensors connecting to a system's control hardware via individual cables, each sensor would simply tie to a network, and all the sensors would then communicate over a single cable. Inches-thick bundles of impossible-to-sort-out wires would be a thing of the past.

The visionary technologists also dreamed that all the networked sensors would be smart. Each sensor would have built-in intelligence and could therefore automatically convert what it senses (a voltage, say) to what a sensor user actually wants (temperature in degrees Celsius, perhaps). A smart sensor could also, by examining its own calibration data, perform minor miracles like compensating for its own deviations from sensor perfection. And, of course, all the sensors would have digital outputs-the better to communicate with the digital network. The network would even be a universal, standard network-no more bloody battles among dozens of incompatible fieldbuses.

Alas, not everyone lived happily ever after in this sensor fairy tale. Although the visionaries' creation-smart-sensor standard IEEE 1451-received official sanction, it was so complicated that virtually no one applied it to commercial applications. And yet, using large numbers of sensors in an application remains complicated and difficult, something that the IEEE standard, for all its own complexities, intended to alleviate. In structural test, for example, you can have hundreds of sensors connected to an airplane or an automobile chassis, and just keeping track of which sensor is plugged into which instrumentation channel is both time consuming and prone to costly error.

Try Again

And so, the visionary technologists are trying again with some proposed modifications to IEEE 1451, one of which-IEEE 1451.4-takes a backward step toward simplicity. Instead of attempting to define know-it-all, do-it-all smart sensors, the proposed IEEE 1451.4 defines so-called plug-and-play sensors that are simply easier to work with. When you add a plug-and-play sensor to a system, the sensor tells the system what kind of sensor it is and what its characteristics are. System software can then use that information to configure the setup automatically. Tedious, error-prone, manual configuration is unnecessary. And, best of all, some of these sensors are already available.

Dual Ouptuts Key - Plug-and-play sensors retain the traditional analog sensor output and add a digtal interface fro reading and writing information that describes the sensor.

Compared to the smart sensors defined by the original IEEE 1451, plug-and-play sensors are very simple. They're not networked; each one connects directly to the instrumentation system. They're not smart, either; they don't contain any processing ability, so they can't perform self diagnostics or use their own calibration data to compensate for inaccurate measurements. What they can do, though, is simply work properly when they're plugged in, with little or no manual intervention.

And plug-and-play operation by itself is a laudable goal, says David Potter, vice chair of the IEEE 1451.4 standards committee and a platform manager at National Instruments (Austin, TX). "It doesn't solve the networking problem," Potter says, "but it does start to add some intelligence to sensors." Also, Potter notes, IEEE 1451.4 establishes an analog sensor connection, rather than digital, as in the standard's first incarnation. Because the dominant sensor interface by far is analog, Potter says, the new proposed standard doesn't require, as the earlier standard did, a major shift in how people use sensors.

The heart of a plug-and-play sensor-and what makes plug-and-play operation possible-is a built-in "transducer electronics data sheet" (TEDS) that describes the sensor and its operating parameters. The TEDS resides in a sensor in a small, inexpensive electrically erasable programmable memory chip (EEPROM). It includes information such as manufacturer, model number, serial number, measurement range, electrical output range, sensitivity, and calibration data. TEDS-aware signal conditioners or instrumentation software can read this information and thereby know how to configure the sensor into the instrumentation system. The system then uses the information to convert sensor data into accurate measurement units.


The advantages of plug-and-play are many, says Martin Armson, marketing director of sensor manufacturer Sensotec (Columbus, OH). For one thing, he says, "Plug-and-play eliminates the need for you to read and enter data from a paper calibration sheet, and you needn't worry that a calibration sheet will get misplaced or lost." Also, Armson says, because sensors vary in sensitivity, swapping one sensor for another in a setup always requires some system readjustment, which plug-and-play systems can handle automatically. "The signal conditioner reads the data from the new sensor's TEDS, adjusts its electronics, and you're testing again almost immediately." Armson notes that reading the TEDS to acquire information about a sensor also makes it possible for a sensor from one manufacturer to work with a signal conditioner from another.

These same advantages ostensibly were available in the original IEEE 1451, however, because that standard also defined a TEDS that made them possible. So why didn't 1451 take off? In short, says Potter, "It was too complicated." Smart sensors as defined by the original 1451 had digital outputs, Potter notes, so even if a sensor were an analog device at heart, it would have to digitize its measurements before presenting them to the measurement system that it operates in. That's an unnecessary step, Potter says, because "we have systems and infrastructure and instruments and sensors all working with analog interfaces."

Another problem with the original standard was that, for many applications, it was overkill. In test and measurement, for example, says Armson, networking is often unnecessary. "You don't have the distances that require networking," he says, "and you don't have the permanent installations, either." In an automotive test application, Armson notes, "You might put in an engine, put all the test equipment on, and then three days later take it all off again. So hardwiring would be much more the norm."

The original IEEE 1451 was sometimes underkill, too, and again in the test and measurement arena. For test, Armson says, as opposed to many other applications, "The data rates required are much higher generally, and often the network doesn't give you the real-time data rates you need."

Analog and Digital

To give test engineers something more akin to what they really need, IEEE 1451.4 keeps sensor signals in analog form and adds a simple digital interface to read the TEDS. Some plug-and-play sensors (notably accelerometers) connect with two wires, just as traditional sensors do, and an attached signal conditioner-by activating a simple circuit embedded in the sensor-can alternately place analog sensor data or digital TEDS data on this two-wire interface. Other sensors have four wires, two for analog sensor data and two additional ones for TEDS data. The TEDS itself is smaller than in the earlier versions of IEEE 1451-as small as 64 bits-because it doesn't have to include some information needed to describe the earlier, more complicated sensors.

In an interesting wrinkle, National Instruments has also introduced the concept of a virtual TEDS, which makes plug-and-play possible even for existing sensors that weren't manufactured with plug-and-play in mind. As Potter notes, "One of the main strengths of 1451.4 is the TEDS, a standardized definition of the critical parameters to describe a sensor and what a sensor does and what its electrical interface is." But that same information is useful to any sensor, Potter says, whether or not it actually has an EEPROM embedded in it. Consequently, National Instruments is creating a database of TEDS files for legacy sensors, which appropriately implemented instrumentation software can access much as it would an EEPROM-based TEDS.

The concept of virtual TEDS is also appealing for some harsh environments. For example, Potter says, "If you have a sensor or a thermocouple that you can't put a chip in, because it's going into a an environment at a thousand degrees, you can get the TEDS information from a file, and your software can use it in exactly the same way."

To increase the chances for IEEE 1451.4's formal adoption, National Instruments and twelve sensor manufacturers have recently established a Plug & Play Sensors Program. As part of the program, NI has introduced a TEDS library that enables use of plug-and-play sensors with its LabVIEW software. The twelve sensors companies are making, or plan to make, products that conform to IEEE 1451.4, even before the standard is ratified, which will probably occur sometime this year. Any changes in the final, adopted standard, they say, can easily be accommodated with software changes.

Real Sensors

Plug-and-play sensors don't yet exist in great abundance, obviously, but they do exist. Sensotec, for example, has made plug-and-play sensors for the past eight years. Its SIG CAL sensors, in fact, served as the prototype for IEEE 1451.4, which makes only minor changes to the SIG CAL's TEDS format. Sensotec has now switched production to 1451.4-compliant sensors and can easily retrofit SIG CAL sensors, via software, to make them compliant also. The company can also retrofit ordinary sensors, by adding both hardware and software, to make them 1451.4-compliant. Other sensor manufacturers active in plug-and-play sensor development include Endevco (San Juan Capistrano, CA), PCB Piezotronics (Depew, NY), and Kistler (Amherst, NY).

Will plug-and-play sensors achieve the success that smart sensors haven't? That's not a foregone conclusion, despite their obvious appeal. Armson notes that Sensotec, a plug-and-play pioneer, still sells far fewer plug-and-play sensors than traditional sensors, with many of them going into test rigs that are set up by engineers, but used by technicians. "This is pretty neat technology because it's simple," Armson says. "Our challenge now is to find people who really want to use it."

Contributing writer Gary Legg can be reached at [email protected].

Resume for a Sensor
Each plug-and-play sensor contains a memory-resident transducer electronic data sheet (TEDS) that contains readable and writable information that describes the sensor and its performance parameters.
Basic TEDS Manufacturing ID Sensotec
Model Number 41
Serial Number 462992
Version Letter 53e
Standard and Extended TEDS Calibration Date April 22, 2002
Measurement 200KN
Response Time 0.0005
Sensitivity 1.998 mV/V
Bridge Impedence in Ohms 350
Excitation Nominal V 10
Excitation Maximum V 15
Excitation Minimum V 3
User Area Sensor Location 23 right dyno
Calibration Due Date April 21, 2003
Templates Special Calibration Data 12.3 + 0.175 + 0.00563x
Wiring Code Wiring code #15

An Ogle at Google

An Ogle at Google

Recent Design News surveys show that Google is the favorite search engine for design engineers who are looking for technical information. Here is what Google is doing to deserve that vote of confidence-and to keep engineers coming back.

Why "Google"?

It's a derivative of a mathematical term, googol, meaning one followed by one-hundred zeros. A googol is a big number and there isn't anything that big in the universe, so it shows that we want to provide an infinite amount of information.

Why do engineers find Google, a general-interest search engine, so useful?

Probably because of our heritage. We began four years ago as a project in the computer science department at Stanford University's engineering school, so engineering was the cultural orientation from the beginning. Actually, we have several engineers on the team who write the algorithms we use. All of them are software engineers today, but many started as MEs or EEs. So, we have an engineering-heavy culture.

How do you structure the search engine to respond to engineering queries?

We don't do that specifically. We write general-purpose algorithms that work well for a lot of purposes, whether you want recipes or technical information.

Okay, then how do you decide what sites to link to?

We look at the reputation of sites on the Internet and we look at who else links to a site, and then we come up with a page ranking. Get a high ranking and we are likely to link to you.

Are you considering adding equations so engineers can do mathematical-function searches?

No, we don't have any plans to do that. For everything we do, we have to consider the cost. We do have a special page, however, for making very specific inquiries. It's called our Advanced-Search page.

How are you going to make Google better?

Sorry, we don't talk about products under development. But you could get an idea of our future by checking out our playground,, where we put up things we are experimenting with. For example, we're experimenting there with a voice-search capability where you could just tell your computer your query rather than type it. Also on the labs site we're experimenting with a glossary of technical terms and a new way to navigate searches.

What do you use Google for?

I use it for technical research, but also for finding song lyrics and directions to places I want to go.

So what enhancements would you like to see?

I would like to see us get more specific, get deeper. We've got 3 billion pages in our web index and we're always expanding that, but I would like to develop more specific products for more specific searches.