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Engineering News 7382

DN Staff

June 24, 1996

25 Min Read
Engineering News

Technology jumpstarts the armchair Olympian

From a microprocessor-controlled tennis-ball thrower to a golf training visor, sporting-goods innovations can get even the most dedicated slouch off the couch

Newton, MA--More people would exercise if only it weren't so...hard. Inconvenient. Time consuming.

Well, technology is doing its best to make those excuses moot: A new reflective fabric coating makes running or cycling at night much safer. Training a visor's light beam on a golf ball can help take strokes off your game. A programmable tennis-ball thrower can put you through your paces without a partner. And multi-featured Timex watches can keep track of all your running stats.

Many people are too busy during the day to get outdoors and run, walk, or bike--and exercising outdoors at night is dangerous. The problem with reflective strips sewn onto clothing is that at night they often appear as unrecognizable series of lines floating ahead at an uncertain distance. But a new clothing material that produces a reflective silhouette image from a 360radius goes a long way toward improving a person's visibility at dawn, dusk, or night.

Started by three MIT alumni, Reflective Technologies, Cambridge, MA, developed the illumiNITEprocess. The goal: a coating that when applied to fabrics appeared invisible during the day but reflected light at night. Further, the coating had to withstand repeated washings, yield a breathable fabric with a soft hand, and come in different colors.

The illumiNITE process embeds millions of microscopic satalite dishes into the weave of a fabric. These particles act like smooth concave mirrors, reflecting light back to the original source. This focuses and maximizes a person's silhouette to motorists.

The coating is applied in a pattern that covers at least 60% of the material--the minimum needed to ensure a distinct silhouette. The satalite dish material is proprietary, as is the method for getting the dishes concave-side-out on the fabric, says Reflective Technologies' Judson VanCor.

Gray, purple, red, blue, green, and black illumiNITE coatings are available on Dupont's nylon Supplex, microfiber nylon, cotton canvas, and Codura (a fabric commonly used for backpacks). Reflective Technologies is currently working on coatings for nonwoven fabrics, such as Lycra.

Laser-guided golf. Golfers whose short game needs im-provement can try another kind of high-tech apparel. The Stabilaser visor from DynaLaser Technologies, Newport Beach, CA, incorporates a battery-operated 5-mW laser-diode module from Applied Innovative Sciences, Tustin, CA. The module generates a bright red light beam that golfers train on the ball to hold their heads steady and in alignment.

Pulling down the canister barrel from the electronics module switches the unit on via a KT Series surface-mount tactile key switch from C&K Components, Watertown, MA. When you tilt your head down to address the ball, a tilt switch turns on the laser, whose light is visible even in bright sunlight.

"The philosophy," says Duane Hreha, general manager of Applied Innovative Sciences, "is that when you're practicing your swing, you want to keep your head and shoulders in alignment while just moving your arms. Unnecessary head and shoulder movement tends to throw off the trajectory of the ball. This device lets you train yourself to keep your head and shoulders aligned when you're initiating your swing and in your followthrough."

Head movement isn't just a beginner's problem. Hreha says PGA players-- including Nick Price--are using the visor to slice strokes off their games.

The Stabilaser visor sells for $99. A stand-alone module that clips onto a golfer's favorite hat is in the works.

Electronics can also help your tennis game. The Ultimate Coach from Crown Manufacturing, Valencia, CA, started life as a custom machine for Andre Agassi, but is now available commercially. The programmable tennis-ball thrower can sequence any variety of shots, and adjust speed, spin, and position to a player's liking. It can also throw twist or slice serves and elevate to 9 feet to replicate world-class serves.

A Philips microprocessor stores, retrieves, and modifies six ball-throwing parameters: velocity, rotation, spin axis, trajectory, horizontal direction, and interval. Memory holds 64 preprogrammed 10-shot drills and up to 64 player-created drills.

You can reach the following companies mentioned in this story via the Internet.
Motorola http://www.motorola.com/
Timex http://www.xmission.com/

On-board logic controls the PWM motor for the three wheels that propel the ball. The wheels' relative speeds determine velocity, rotation, and axis, so these parameters can be adjusted without mechanically moving the wheels. The 90V dc motors can accelerate the wheels at 50 mph/sec.

Despite all the electronics, the unit is designed for easy operation. A player makes choices from the control panel's on-screen menu. Cursor control lets players increase or decrease parameters; move a shot up, down, left, or right; or choose another shot. Next for Crown: adapting the technology to improve baseball-throwing machines.

On track. The Timex Ironman Triathlon watch is aimed at helping runners monitor their progress. Features include a 100-hour chronograph with lap and split, 100-lap memory recall, and a training log that stores lap and split times as well as best and average laps and dates. Prices range from $55 to $60.

The second model of Timex's Data Link watch family, the Data Link 150, lets users optically download both data and programs from a PC via a CRT.

Developed by Timex and Microsoft, WristAppssoftware includes customizable programs for taking medications, exchanging money, scoring golf, or keeping track of jogging laps. The $139 watch also includes a stopwatch and countdown timer.

Data Link watches are powered by an 8-bit 68HC05 Motorola microprocessor with 24 kbytes of ROM. Both watches include the blue Indiglo backlight, controlled by a tiny Motorola analog driver.

Travel is the excuse many people use for not exercising. A new product from Motorola won't help you stay in shape, but it will help you keep up to date on your favorite baseball teams when you're on the road.

The size of a pager, Sports-Traxis a wireless monitor that provides continuous batter-by-batter updates of any ongoing baseball game. The unit displays the score, shows the position of base runners, and indicates the inning, team at bat, and number of outs.

"Our research shows that time is one of sports fans' biggest problems," says Mike Marrs, SportsTrax general manager. "SportsTrax frees up the three hours you'd spend watching or listening to a game, but lets you keep tabs on your team."

State-of-the-art satellite technology lets fans use Sports-Trax in most cities, allowing travelers to monitor their favorite teams almost anywhere on the road. Buyers pay a one-time retail price of $199, which includes SportsTrax and complete coverage of Major League Baseball regular season and playoff games through the end of the 1998 season.

Once the boys of summer leave us and basketball season starts anew, you can track every NBA game with the SportsTrax basketball version. But first, let's get the most out of the warm weather--we've waited for it long enough.

--Julie Anne Schofield, Associate Editor

Microsoft sponsors CAD award

Newton, MA--Design News recently established an Excellence in Computer-Aided Design Award as part of its Excellence in Design Awards program. The new award honors the lead engineer of an outstanding new product whose success can be traced in large part to PC-based computer tools--both hardware and software.

The award-winning engineer will receive a $5,000 prize and will designate an engineering school to receive a $5,000 grant. Microsoft Corp. will fund both the prize and grant. "We thought it was time to give credit to the millions of engineers and designers who are creating products on personal computers," says Matt Ragen, worldwide marketing manager for the engineering and mapping industries at Microsoft. "Advanced 32-bit operating systems such as Windows NT Workstation and Windows 95 enable the most advanced applications to run on personal computers. This award will recognize the impressive design and analysis work that these engineers are performing day in and day out."

By participating in the Design News awards program, Microsoft joins a distinguished group of long-time award sponsors. At Design News' most recent banquet, these companies donated more than $100,000 in prizes and college grants in the name of some of the country's most talented design engineers.

The first Excellence in Computer-Aided Design Award will be presented at Design News' 10Annual Engineering Awards Banquet at the Annual Design Engineering Show, Chicago, in March 1997. This annual award will help acknowledge outstanding creativity in the use of computers for the design of manufactured products.

"We want to salute the role that computers--in particular personal computers--have played in speeding time to market and vastly improving the quality of engineering design," says Design News Publisher Lawrence Maloney.

The winner will share the spotlight with some of engineering's most important figures. These include the individual voted by Design News readers as the Engineer of the Year, the recipient of the Special Achievement Award, and the winner of the Engineering Quality Award.

HP triples mid-range power

Chelmsford, MA--Hewlett-Packard has roared into the mid-range workstation price/performance leadership spot with the first desktop computers designed around its new PA8000 processor. "They've tripled floating-point performance over the 7200 processor, which they had before, at similar prices," says analyst Peter Lowber with Datapro. "That's pretty astounding."

The HP Visualize work-station family starts at $22,520 for a Model C160 (with a 160-MHz CPU) and $49,520 for a Visualize-48XP. PA8000-based machines are also available in more powerful deskside models: the K260EG/K460-EG and K460XP.

The C160 workstation is rated at 17.5 SPECfp95, an industry benchmark measuring floating-point speed. (Floating-point operations are used in complex mathematical calculations, such as engineering analysis.) Lowber says the nearest major competitor in the same price range is at 12.3 SPECfp95. "It's been a long time since HP has been the leader," he notes. "They had slipped behind the last few years. Now, they've bolted ahead again."

The company also unveiled Visualize-EG graphics for PDM and 2-D drafting; and XP for 3-D assembly, virtual prototyping, and concept design.

In an earlier, separate announcement, HP announced the Exemplar SPP 1600 high-end technical system, delivering up to 60% more performance over the older SPP 1200. The machine comes from Convex, recently acquired by HP. "We are aiming for absolute leadership in technical computing," said Ron McKenzie at HP's Workstation Systems Division.

Relay replaces contactors in three-pole applications

Milwaukee--Engineers at Deltrol Controls have developed an electrical relay that could eliminate the need for bulky contactors in 30-Amp, three-pole applications. The new relay is about two-thirds the size and one-fifth the weight of similarly rated contactors.

Key to development of the new device is use of a specially designed contact/terminal assembly. The assembly consists of a cold-extruded silver cadmium oxide (AgCdO) contact that is cold bonded to a copper rivet. Because the assembly's cold-forming process suppresses arcs, it eliminates the need for large springs and electrical coils, which previously were used to overcome contact-welding problems. As a result, the new relay is dramatically smaller than similarly rated contactors.

Known as the 375 General Purpose Relay, the device is the first to employ cold-formed AgCdO technology in a three-pole design. Deltrol engineers previously used the cold-formed contacts in a two-pole relay (Design News March 7, 1994), resulting in similar downsizing of the product. But employment of the same technology in a three-pole design required more engineering effort, they say. The reason: The three-pole design generated more heat, which was more difficult to dissipate in the unit's small package.

To deal with the heat and still maintain the small package size, Deltrol engineers employed a unique thermoplastic-insulation system around the coil and a special poly-phenylene sulfide (PPS) material in the relay's panel. The new magnetic circuit, together with the PPS insulator, keeps the temperature rise of the coil to a manageable level, say Deltrol engineers.

The three-pole design is ideal for HVAC and refrigeration applications, or where banks of bulky contactors are used for three-phase motor control. "In the 25-30 Amp range, this is a great lower cost alternative," notes Nikola Rajnovic, a Deltrol design engineer. "In many cases, contactors delivered more power than was necessary."

--Charles J. Murray, Senior Regional Editor

Potentiometers survive radiation-therapy environment

Palo Alto, CA--Potentiometers may be one of the simplest absolute position sensors. But engineers at Varian Associates specify more than 13 of them in the company's line of Clinac radiation-therapy machines. Immune to the millions of rads of radiation that hit them during their lifetimes, the potentiometers--produced by Spectrol Electronics (Ontario, CA)--are trusted with monitoring the position of most of the machine's critical motions.

One potentiometer regulates each of four 70- to 80-lb aperture tungsten plates, or "jaws," that move to restrict the X-ray or electron beam to the size and shape of the cancerous tumor being treated. The jaws can define fixed apertures from 0.5 cm 0.5 cm to 40 cm 40 cm. They can also be moved dynamically during an exposure to modulate the beam's intensity in a process similar to dodging and burning in photo processing.

Spur gears link the potentiometers--sometimes called pots--to the jaw control motors. Each sensor is equipped with ball bearings to withstand high side loading.

Other pots control the rotation of the collimator and the machine's gantry location. The couch, which adjusts to best orient the patient, also relies on potentiometers. "We use pots because they are robust, they can take the radiation, they're inexpensive, and the number of interface wires is low," says Jeffrey Tuttle, senior engineer at Varian Associates.

He has considered other sensing technologies, such as encoders, to obtain increased accuracy and precision. But he always returns to potentiometers for their unbeatable price/performance and ability to provide absolute position, even when the power is off.

Varian Associates' Clinac radiation-therapy machines range from the model 600C, which generates 4 to 6 mev of radiation, to the 2300CD, which produces up to 22 mev. Treatable cancers include breast, prostate, and Hodgkin's disease.

--Mark A. Gottschalk, Western Technical Editor

Thermostat holder puts the freeze on antifreeze

Southfield, MI--When Bavarian Motor Works (BMW) decided to redesign its thermostat assembly, the automaker switched from a nylon material to a glass- and mineral-filled polyphenylene (PPS). The reason: PPS' ability to withstand ethylene glycol-based antifreeze at high operating temperatures.

BMW injection molded the nylon part prior to redesigning the component for automated insertion of the thermostat. The redesign, used in BMW's four-cylinder, two-valve M43 engine, includes two inverted J hooks to hold the metal thermostat. The inverted hooks have opposite-facing key-ways that allow the thermostat to be inserted, then turned into the locking position. The thermostat spring exerts up to 300 newtons of pressure to hold the unit firmly in place.

During testing at normal operating temperatures, glycol/water antifreeze moving through the thermostat assembly at about 275F caused the nylon J hooks to fail. BMW designer Gerhard Beier discovered that the nylon softened because it became hygroscopic in contact with the antifreeze. This, in turn, severely degraded the polymer formulation.

"We used polyamide for several years in the old design that didn't have the J hooks," Beier explains. "One end connected to the radiator; the other, with the thermostat inside, was bolted to the engine block. We added the hooks to reduce manufacturing time and assembly costs."

Once Beier discovered the J-hook failure, BMW molded some test parts from RytonPPS supplied by Philips 66 Co., Bartlesville, OK. The tests involved using the polyamide prototype mold, low mold temperature, and standard Ryton PPS processing conditions.

"When our first Ryton PPS prototypes achieved 1,000 hours of rated-use life without failing, ten times that of nylon 6/6, we stopped the test," Beier recalls. "It truly surpassed my expectations."

For the first test prototype, Beier selected Ryton R4XT PPS, a toughened glass-filled compound. "We purposely over-engineered the material selection at this point," he explains. "We have now switched to Ryton BR83B PPS, and are testing Ryton BR111 PPS."

Ryton BR83B, a high-strength, glass- and mineral-filled compound, holds up well in mechanical applications. It has a tensile strength of 21.0 ksi, a density of 1.80g/cc, very low water absorption, and resists temperatures of more than 500F. Ryton BR111, a new glass- and mineral-filled grade, improves on the inherent qualities of Ryton BR83B. It has demonstrated added creep resistance and high torque retention.

The original thermostat holder, developed to save space in the engine compartment, consisted of aluminum. Designers then chose the nylon material. The switch to PPS resulted in a cost saving of 30% and weight saving of 40% when compared with the original aluminum part.

Slide adds function to dental laser

Rochester, NY--In 1896, engineer Octave Chanute set out to give credibility to the notion that man could fly. On the Southern tip of Lake Michigan, Chanute and his crew carried out an historic gliding experiment with his then-revolutionary biplane aircraft.

Now, for the 100th anniversary of those flights, a design team at the Rochester Institute of Technology has chosen to undertake the construction of a full-scale replica of the glider using modern materials and structural-analysis techniques but maintaining the original design and aesthetics.

The team's five students have performed analyses using software from Algor, to determine the various stresses. They also produced AutoCAD drawings of many of the parts. To determine the actual safety factor of the parts, much of the testing has been done on a tensile test machine.

Before the glider was assembled, the team determined that the fasteners and fastening plates, as well as the ribs and the other members that are joined, can stand up to the stresses of flight.

The students also focused much of their design work on manual testing. "The Algor analysis gave us a ball-park figure, but obviously we could not load up the whole wing," explains Kevin Kochersberger, a visiting assistant professor at RIT. "I have to say that I am amazed how much testing has been done. In fact I think that in the end every part in the biplane will have been busted so we know it will stand up to huge loads."

While Octave Chanute used the most state-of-the-art materials he had at his disposal, the team decided to update his choices. Rather than spruce, 70% of the components have been made out of carbon epoxy. The ribs and the struts which hold the wings apart, as well as the tail components, are made of carbon. The spars and the boom going back to the tail are both made of aluminum tubing. While Chanute used muslin to construct the wings, the students chose Dacron. The modern materials helped keep the weight of the aircraft down to about fifty pounds.

The National Soaring Museum, Elmira, NY, is sponsoring the project and will display the aircraft for two years. It will then be moved back to RIT. There will be a dedication sponsored by the Chicago Glider Counsel in July on Miller Beach, where the original flights took place.

3-D tools boost power to transformers

Melbourne, Australia--Transformers Mfg. Co. Pty. Ltd. (TMC) recently decided that in order to remain competitive, the company had to reduce time-to-market and improve product quality. Addressing those challenges meant leaping from manual engineering to full-blown 3-D modeling.

TMC designs and manufactures a variety of one-of-a-kind transformers and special induction equipment, including cast resin encapsulated, open-winding dry types, and oil-cooled transformers. This type of work results in design costs representing a high proportion of total product costs--higher than if one design could be used to build multiple units. According to Jeff Brown, research and development engineer, "Because we start at the beginning for every new transformer, we realized the time-savings we would appreciate by using mechanical design automation software. By building a generic model, I can modify it according to new product specifications."

After evaluating several software systems, TMC selected I-DEAS Master Seriesfrom Structural Dynamics Research Corp.(SDRC), Milford, OH. Because this was new territory for the engineers, ease-of-use was important. "The Dynamic Navigator is not only easy to use, but it actively helps users construct models," adds Brown.

Mechanical design had traditionally been carried out by sketching several 2-D views. With I-DEAS solid modeling and structural finite element analysis (FEA), Brown believes users can improve all aspects of their designs.

"With the increasing cost of materials, the FEA optimization functionality is a useful tool to determine how to reduce the volume of material used," Brown explains. By using optimization algorithms on the walls of their tanks/enclosures and structural members, for example, engineers were able to cut material costs.

"I-DEAS Master Series offers synergy among solid modeling, analysis, and drafting," Brown says. "TMC can reduce modeling and redesigning, as well as eliminate the need to learn several separate software systems."

Engineers race to redesign Formula One cars

Oxford, UK--Today's automakers are pleased if they can squeeze design time down to three years for a new vehicle. Formula One engineers, however, have to redesign cars for the new racing season in less than a year.

That means fast and easy communication between engineers is critical, according to Fred Mundle, IT manager at Benetton Formula Limited's technical center. "We were a bit sketpical at first about the value of tools such as multi-media mail and shared whiteboards," he says. "But when we sat down to analyze exactly how we work and how often people are on the move, then we had no doubts about their relevance."

The Formula One governing body issues strict guidelines for racing cars each year, requiring all the racing teams to redesign their autos annually. The team also makes modifications between races once the season begins after studying the car's performance--putting immense time pressure on the engineers.

"We only have four days between each race before we leave for the next," Mundle says. For example, following a race in Portugal, the team made 251 detail design changes in a week. "Our ability to respond to that rate of change has a direct influence on our competitiveness," he says.

Benetton engineers used to be split into different groups, each working on a different section of the car almost in isolation. Computer networking and communications technology has allowed much closer collaboration early in the design process, Mundle says. "CAD reduces the risk of the car not fitting together," he says.

The Benetton team uses about 40 HP 9000 workstations running various software packages, along with HP's collaborative multimedia software package, MPower 2.0. An initial design team creates a 40-percent model of a full-size car, which is then tested in a wind tunnel for optimum aerodynamics. Once the team is satisfied that it's squeezed out the best possible performance from the car's shape, the model goes to another group for detailed design and engineering work using EDS Unigraphics software.

The detail work is done about 65 miles away from the wind tunnel, but engineers can see video clips of air flowing over the model in the wind tunnel (a camera is placed in the tunnel and smoke blown over the car). Engineers at different sites share CAD drawings over an MPower link and changes can be finalized faster during a video conference. There's even a hand-held video camera and HP workstation at each race site, so team members on the racing circuit can quickly send movie clips of the car in action back to the other engineers.

"Before, we tried to describe a problem over the telephone or fax a drawing," Mundle says. "This way has had a dramatic effect on the quality of the decisions being made."

Syringe filters prosper with polyester

Bedford, MA--After extensive review of available resins, Millipore, makers of filtration devices for medical, pharmaceutical, and laboratory clients, switched to a copolyester in the manufacturing of its disposable syringe filters. Fitted at the end of a syringe, these filters remove harmful particulates from the solutions that pass through them.

Millipore did rely on PVC to produce the filters and the blister packaging they are shipped in. However, faced with the disposability problem of PVC and some questions regarding residue from ethylene oxide sterilization for the filters, the company turned to gamma-ray sterilization--and a new material for product and packaging. That material: EastarDN003 PETG (glycol-modified polyethylene terephthalate) from Eastman Chemical, Kingsport, TN.

Millipore did extensive testing in its search for the replacement, according to Donna Gasper, manager of manufacturing. "We looked at dozens of materials," she adds. "Our requirements were demanding. We compared candidates to PVC in terms of burst characteristics and price, overall strength and color, and whether it would survive our 'cone test'--jammed on a syringe without breaking. Most importantly, the material had to maintain color and performance characteristics after radiation."

The filters come in varying pore sizes color-coded by membrane: 0.22 micron (which screen out bacteria, since all bacteria are larger than 0.22 micron), as well as 0.1, 0.45, and 0.65 micron. "With each test, DN003 came up the superior choice; the one closest to PVC," Gasper notes. "Nothing else came close. Subsequent testing confirmed this selection."

In another switch, Millipore chose Eastman's Eastar copolyester for the packaging. This time the decision was based on the material's inherent clarity and strength.

LaserPour replaces manual system

Indianapolis, IN--Chrysler Corp. has realized a substantial savings in molten metal by updating its pouring system.

The automaker's Indianapolis foundry, a supplier of engine blocks for assembly plants throughout North America, casts up to eight different types of engine blocks--with molds often intermixed. This requires virtual on-the-spot pour adjustments.

The foundry turned to a LaserPour Automatic Pouring Control System from Selcom, Southfield, MI, to handle the demands of on-the-fly changes. The system uses a laser-based level sensor to provide real-time data on the pouring cup's metal level. By controlling the position of the stopper rod, the flow of iron into the cup is constantly adjusted by the system to meet the mold intake rate. This built-in consistency virtually eliminates slag inclusions, without any delay in the pouring process.

Since installing the system in July 1994, the foundry averages iron savings at 500 tons a month, or 8.5 lbs for each sprue cup poured.

During normal operation, each of the two pour cups on a flask feed iron for one or two engine blocks at an average capacity of 3.5 blocks per flask. Total pour time per mold is 16 to 24 seconds. On average, 900 lbs of iron is poured per mold. Before installing the LaserPour System, the pour cup weight was 34 lbs, not including gating. "Our goal with LaserPour was to optimize the level of iron in the sprue cup at .25 inch from the top of the mold," notes a Chrysler spokesperon. "Of 5,000 molds audited this past fall, we found that only 16 exceeded the specified level."

LaserPour's success in iron foundries recently prompted Selcom to transfer the technology to primary aluminum casting. The company now offers systems for level control during billet, ingot, and slab casting, as well as horizontal strip casting.

Slide adds function to dental laser

Fife, UK--Linear slides may soon at be at work in your local dentist's office. A new portable dental laser uses slides from Hepco Slide Systems Ltd., Devon, UK, to guide and retract the system's hand-held tool.

The OralMedic5 from MLT Ltd. is a carbon dioxide-based dental system for treating soft tissues. The compact instrument generates a laser beam of 10.6-micron wavelength to accurately excise tissue for treating gingivitis or conducting other minor oral surgery. Unlike conventional surgery done with a blade, the intensity of the laser beam helps to seal wounds as it cuts. This reduces blood loss and speeds recovery, say MLT engineers.

The OralMedic's portable base unit houses the laser, a mirror for directing the beam, and controls. To use the instrument, the dentist removes the retractable hand-held tool, which delivers the laser through a fiber-optic cable.

In order to make the overall system compact and less expensive, MLT engineers selected Hepco's Generation II linear slide system. The slide system guides the hand-held tool on a precision-ground slideway and aluminum carriage plate. The slide rides on two concentric journals and offers two eccentric journals for system adjustment. "This allows the engineer to adjust the preload at the manufacturing stage, rather than specifying it up front," explains Hepco international sales manager David Clements.

The Generation II gives engineers the option to specify a variety of components as a pre-assembled, off-the-shelf, ready-to-install unit, adds Clements. Three sizes of cap seals add the ability to seal, wipe, and lubricate the linear slide.

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