Oxygen for human use produced with extraterrestrial resources
Bruce Wiebusch Regional Editor
Tucson, AZ--Engineers at the University of Arizona's Space Technologies Laboratory are perfecting an oxygen generation system (OGS) that converts CO2 gas into carbon monoxide and pure oxygen. The OGS, which uses synthetic ruby orifices instead of conventional valves, is currently scheduled to fly aboard the Surveyor spacecraft to Mars in 2001.
The OGS uses three synthetic ruby orifices. One regulates CO2 into the OGS. Another regulates CO/CO2 out. The third regulates oxygen out of the system (see figure).
"Use of valves or throttles for flow regulation isn't an option," says Bruce Borches, a mechanical engineer at the university who helped turn the concept of an OGS into flight hardware. No repairs are possible once Surveyor leaves Earth, so the system has no moving parts. A weight limit of approximately 2 lbs also limits flow-regulation options.
Conditions on Mars also mandate that the system operates in temperatures down to -100C and pressures less than 100 kPa at the inlet. Ambient pressure on Mars is &1 kPa at the OGS exhaust. Modeling the system flow through the orifices using the Bernoulli principle is not an option because the Bernoulli principle applies to steady frictionless, incompressible flow, which is not the case with this system that has a restrictive orifice in a gas stream.
Using an orifice provides a repeatable pressure drop for any given flow rate through it. "With careful calibration, the flow rate versus pressure drop curve is accurately characterized for any given temperature," says Borchers. "By putting more than one orifice in a flow path and selecting appropriately sized orifices, any selected flow rate/pressure drop combination is achieved," he notes.
The pressure versus flow curve becomes very steep by severely restricting the flow with a small orifice. Increasing drag as the velocity of gas increases allows for control of flow in the system and the prevention of system damage from an over pressurized inlet stream. "With the addition of inlet and outlet pressure/temperature sensors, the University of Arizona engineering team achieved desired flow rates.
The design engineers selected synthetic ruby orifices from Bird Precision (Waltham, MA) for several reasons, according to Matthias Gottmann, an assistant research professor at the university. "We needed a material that was reproducible and resistant to large temperature fluctuations," he said. The modulus of elasticity for synthetic ruby is 4.4 X 106kg/cm2 ±1%.
"The OGS is part of an effort to move away from the BYOE (Bring Your Own Everything) approach to space travel," according Gottmann. Oxygen is important to the Surveyor and flights to Mars for both life support and fuel. "Hauling enough oxygen for trips to and from Mars is expensive. Bringing the means for making oxygen cuts expense by approximately 30%," says Gottmann.
Precision components just keep on going and going and going...
East Rockaway, NY--"Despite the advent of electronic controls, there's a strong and growing demand for the mechanical portion of motion control solutions," says Rich Halen, president of W.M. Berg, a manufacturer of miniature precision mechanical components for more than 30 years. "In fact, some of the most sophisticated devices being made today still have gears and sprockets and couplings and other drive components."
Sales of precision components with extremely high tolerances (0.0005 inch) are stronger than ever today, due to a booming market for precision inspection equipment, data storage tape backup systems, lab testing equipment, machine tools, and, well, you name it. "From coffee makers to ATMs to lottery ticket machines to theme park animatronics to the space shuttle, the breadth of applications for our components is fairly impressive," says Halen.
Berg, which makes 70% of the products it sells, has always prided itself on its precision manufacturing capabilities. But the biggest change impacting design engineers has been the drastic reduction in lead times--from weeks in some cases to a matter of days. Some 60% of the orders Berg receives for standard parts ship in 24 hours, thanks to a new flow-through production system.
"Our parts are usually such a small part of a project that engineers frequently fail to order them ahead of time," says Halen. "Now, we can usually fill even last-minute requests."
Molding's Paul Bunyan
Bolton, Ontario, Canada--With 8,800 tons of clamp force and a 207-ton nodular iron casting for a moving platen, this new molding machine from Husky Injection Molding Systems is the largest of its kind in the world, according to its maker. The machine recently went into operation at Husky's new technical center in Novi, MI. The first part off this monster molder was a 32-lb outer half for DaimlerChrysler's Composite Concept Vehicle, which features a glass-filled thermoplastic body. DaimlerChryler has also used the machine to run prototypes of a large, two-piece roof for the 2001 Jeep Wrangler. Representing a glimpse at the future of large-part molding, the machine is expected to make new kinds of large parts--including truck liners, appliance enclosures, boat hulls, and modular swimming pools.
Press operators gain PC-driven controls
Los Angeles--The Los Angeles Times, the country's largest metropolitan newspaper, with a daily circulation of 1,098,347, has upgraded its press controls on 16 Goss printing presses with a Rockwell Automation PrintLogix system.
"We're upgrading the press supervisory controls, operator consoles, and dc drives to better control and monitor ink, water, and print registration, as well as adding PLC's to provide management information," says Gerry Niebler, project manager with Rockwell Automation.
"A newspaper is a brand new product every single day and changing out equipment is like changing tires on a moving car," says Gordon Tomaske, operations business manager with the Los Angeles Times. The Times runs 14 to 15 presses at once at high speed to print more than 1,000,000 copies for each morning paper.
PrintLogix™ architecture combines IBM-compatible PC hardware, Windows NT-based software, and Allen-Bradley PLC's with Allen-Bradley drives and Reliance Electric motors. The system simplifies plant-wide control and integrates pre-and post-press operations, such as paper roll storage and retrieval, and web feed control. The system helps the Times coordinate daily orders--each section, number of color pages, and printed copies--by press, and configure each press to make the page count.
With the PlantView™ supervisory control and data acquisition software, users can view the entire site's printing application from a single operator terminal. The system consists of new operator consoles with PressView™ software for press operator interface. PressView allows job pre-setting to shorten set-up times, resulting in faster press runs and less paper waste. The software also allows adjustments to be made to correct color-to-color registration errors and misadjustments in ink densities.
The Times swapped existing dc analog drives with new Allen-Bradley 1395 digital dc drives to power and control line-shaft movement. The large Goss Colorliner presses use one drive set to run the line shaft with 12 drives sharing the load to generate the 1,400 hp needed to power each press. "Our greatest need was to remedy obsolescent drives with the new system," says Los Angeles Times' Tomaske. "Yet we feel it is modular enough to allow for ready upgrade."
According to Tomaske, the new press controls provide diagnostics at the operator's console, unavailable with the old system, including drive status and ready information, overload conditions, ac line status, failed thyristor within each drive, out of tolerance, and other failure alerts. New Allen-Bradley 1395 digital dc drives also control the running belt reelstands and communicate the same information to the operators.
The PrintLogix system design includes a press-wide ControLogix controller used for good count/waste count, first web break detection, roll mileage, tension monitoring, ink change logging, and other auxiliary functions.
PrintLogix is a flexible system with a clear migration path, says Rockwell's Niebler, allowing initial installation of a base system and later change out of unit controls one-by-one without interfering with press operations.
E-catalogs ease design crunches
Long Beach, CA--First, you have to convince a manufacturer you're serious about your catalog request and worth the price of postage, then the waiting begins. In fact, David Douglass, product designer for Alesis Studio Electronics in Santa Monica, CA calls tracking down, requesting, and waiting for print catalogs, "the single biggest time waster in engineering today." Douglass, who specifies connectors and fasteners, opts for online catalogs to save precious design-cycle time.
Understanding that access to online product information eliminates delays, suppliers are building content-rich interactive sites. Some provide detailed product information. Others allow plug-n-play download of CAD drawings and online ordering.
A standout site is Penn Engineering and Manufacturing's www.pemnet.com. The Danboro, PA-based motor maker has built a complete web-based catalog, searchable by part number or product characteristics. The site matches the part number to specification criteria, such as fastener thread size, type, and material. Once the user has reduced the search to a single part number, detailed specifications, simplified engineering drawings, and product photographs are presented. The site offers downloadable CAD files in IGES format, Mil and NAS spec tables, and measurement conversion utilities. Small, quick-to-download PDF files can be stored for ready reference without having to retain a complete catalog of parts.
With more than 95,000 parts on its site, Harrisburg, PA-based AMP (connect.amp.com) provides complete specifications, multiple search, and select modes. Recognized volume buyers can enter an e-commerce zone to purchase online, but first-time buyers are restricted to a few online products.
To save time designing linear motion systems, access Bishop-Wisecarver's site (www.bwc.com) and download a linear drive or slide system as a PDF or AutoCAD file to integrate a component into your design. Or, use an AutoCAD plug-in called SmarTrak, to create custom drawings to your equipment specifications.
Bishop Wisecarver's Lo Pro system features modular units with a load capacity of 5,000 lbs and speeds over 500 inch/sec. Select Lo Pro track types, belt, chain, lead screw or pneumatic drives, drive ends, shafts, wheel plates, and track lengths, then quickly generate AutoCAD drawings with different views of your custom system.
"The old way--huge palette directories of component drawing files with names that are not very descriptive of what you want--is cumbersome and confusing," says Vice President of Engineering Bill Harris. "Lo Pro SmarTrak allows quick drawing, sizing, and integration into your application."
In the market for liquid level or flow sensors? Try QwikPiks, an online service from Gems Sensors (Plainville, CT; www.gemssensors.com). The program promises same-day shipping for credit card customers and purchase order accounts. Products can be browsed by category, sorted by application requirements, or searched by part number. All three routes lead to detailed product specifications, including dimensional drawings in PDF format.
Rockwell Automation's contract customers (www.automation.rockwell.com) can order on line as of this spring, as well as access product descriptions, manuals, and support from Dodge, Allen-Bradley, Reliance Electric, and Rockwell Software. "We want to create a community of our customers, distributors, manufacturers, and suppliers, to offer better ways to do business," says David Yeghiaian, e-commerce marketing manager with Rockwell Automation. Rockwell built the site in-house, with amazon.com and travelocity. com as models. The site, which promises "three clicks to an order," experiences 2 million hits and 600,000 file downloads a month, says Yeghiaian.
Precision casting beefs up wear pad support
By John Lewis Northeast Technical Editor
McConnellsburg, PA--JLG Industries, a manufacturer of aerial work platforms and telescopic material handlers and excavators, recently worked with PIAD Precision Casting (Greensburg, PA) redesigning a wear-pad support on its 600 Series boom lifts. As a weldment, the existing wear-pad support was too costly to manufacture and too time consuming to apply. So JLG formed a re-engineering team with in-house production staff led by Cary Rosenburg, and then consulted with Larry Harnish, senior product specialist from PIAD. Within 18 weeks, the part, now redesigned as a casting, cut component cost and weight 50%, and assembly time 80%, all while increasing part strength 40%.
The wear-pad support, also known as a mounting block, attaches to the telescoping cylinder. It functions as a spacer, occupying the area between the cylinder and the boom tube to smooth movement during boom extension and retraction.
During installation, the support's top plate is bolted to the end of the telescoping cylinder; the bottom plate is attached to a Nylatron wear pad that contacts the inside surface of the boom. Given its support function, mounting block durability is a key design consideration.
Previously, as a weldment, the wear-pad support was laboriously made from six individual, flame-cut pieces of steel plate. The pieces were inventoried, then pulled from stock to be welded together into a single weldment that was machine finished and painted. Two people were needed to install the completed part during the assembly process.
To solve these problems, the re-engineering team first considered casting the part rather than welding. Input from production employees at PIAD produced an entirely new design. Over a two-week period, the team contributed a number of wide-ranging ideas. The production floor recommended staggered boltholes to allow easier air-wrench access during installation. Other recommendations resulted in an ergonomically correct shape that allowed a single worker to pick up and bolt on the new piece. And PIAD engineers determined the part characteristics that would optimize casting yield.
"For casting this component, we use a permanent mold casting process called a chill-mold," says PIAD's Harnish. "We created a steel die that contains the elements to produce all the needed features in the mold. After casting, the steel-die mold is quenched, to produce the chilling effect. The permanent mold process is ideal for meeting the tolerance requirements of a complex shape. Plus, it provides a competitive unit cost for short run products." JLG uses approximately 50 of the castings each week.
Harnish recommended AO21, a specific nickel aluminum bronze alloy that is highly corrosion resistant and does not require painting. From and industry standard viewpoint, PIAD's AO21 is comparable to C-954.
JLG engineers developed a rough drawing of the part and then input the dimensions into a Pro/ENGINEER 3D CAD/ CAM program (Parametric Technology Corp., Waltham, MA). The software made it possible to generate a virtual solid model of the wear pad support to check interference without developing a mockup part. JLG presented the design to PIAD for mold development. In 12 weeks, the mold was completed, and 32 prototype parts were produced. Two weeks of function, form, and fit testing followed.
A coordinate measuring machine verified the parts along 20 critical dimensions. Samples were then subject to stress tests for bending, warping, twisting, and cracking. In applications testing, the part was subject to twice its normal load and to 66-ft boom extensions instead of the normal 60 ft. The cast prototypes passed every test, and PIAD provided production quantities to JLG just two weeks later.
In the flow of production and assembly, explains JLG's Rosenburg, the re-engineered part has provided even more benefits. "The part is not only easier to bolt on, but assembly workers also find it's easier to route cabling through an offset on either side of the support because the new design has no weldment lip."
PIAD drop-ships the parts in pipeline production quantities to satisfy JLG's just-in-time manufacturing model. When a new carton of castings arrives, it's placed directly at the point of use. "This completely eliminates the stocking and inventory hassles we had with weldments," says Rosenburg.
While improvements in cost, reliability, and performance have been substantial, just as important are the rewards workers feel on the factory floor. As with many such projects at JLG, the company emphasized the input of manufacturing floor workers to the design and the supplier's contribution to the improvement process.
Glass-filled soles move Michael
By Joseph Ogando Mid-Atlantic Technical Editor
Beaverton, OR--On your mark. Get set. Go! In the never-ending race to build a better racing shoe, Nike engineers rely on the perceptions of a very fast man named Michael Johnson.
When Johnson dashed to a 400m world record in Seville, Spain last August, he did so on Nike shoes engineered with his help. Tailored to fit not just the runner but also his running style, these shoes feature a new sole plate that, at 30 gm, weighs half as much as previous designs while maintaining a delicate balance between stiffness and flexibility.
Nike started out with its own design targets. According to Senior Advanced Project Engineer Tobie Hatfield, the sole plates need to withstand 10,000 flex cycles at forces ranging from 350 to 450N. They must also recover from a 45° bend without cracking or permanently deforming.
But Johnson's feedback mattered more than the numbers. "The most important thing was understanding how Michael runs," says Hatfield, explaining that Johnson's ideal "400" consists of a fast, controlled 200 meters followed by an even faster second half. "In the second 200, Michael turns on the afterburners when the other guys are just trying to hang on," Hatfield adds. This kind of dynamic style, coupled with the four corners in a 400m race, called for a sole plate that had a dual role. It had to be flexible for the turns and controlled first half of the race, but still stiff enough to help Johnson stay up on his toes. And of course, at Johnson's level of racing, the shoe had to be light.
To home in on the delicate balance between stiffness and weight, Nike designers decided to forego the traditional unfilled nylon-12 sole plate and instead try a glass-filled, toughened nylon, Zytel from DuPont (Wilmington, DE). "At first, we didn't know exactly how much stiffness Michael wanted," notes Hatfield. "And I was skeptical that a sole plate with any glass at all would still meet his flexibility requirements." But after trying prototypes with glass loadings from 10 to 33%, Johnson settled on a sole with a 13% glass filling. The material Johnson chose is about 40% stiffer than the unfilled nylon used in previous designs.
The sole plate also achieves some extra stiffness through a thickening of sections that fall under the toes. These "power pads," as Hatfield calls them, add stiffness where it's most needed without the weight increase and loss of flexibility associated with an overall thickening. These pads, an idea borrowed from Nike's distance shoes, add about 0.5 to 0.75 mm to the nominal sole plate thickness of 1 mm.
Beyond material choice, Johnson's input also informed a drastic redesign of the shoe's traction elements. Yet rather than relying just on the runner's verbal responses, Nike's engineering team went out in the field to do a slow-motion video analysis. "By observing how his feet strike and roll, we knew where to place traction elements and where we could take them away," says Hatfield.
And take away, they did. Instead of ten screw-in spikes, the new shoes sport only five aluminum spikes integrated through an insert-molding process. This arrangement saved a few grams by doing away with the screw-in-spike receptacles, but it also created a need for more traction. To make up for the missing five spikes, Nike engineers added more than 100 secondary traction elements--molded-in ridges and bumps.
Nike will commercialize the design late this year.
Digital x-ray cameras reach the factory floor
Santa Clara, CA--X-rays are a great way to see inside things without taking them apart. But because there is no way to focus x-rays, the x-ray source, the object of interest, and the detector, all must be precisely aligned--a task that requires complicated jigs and fixtures that aren’t always practical in industrial and commercial applications.
With production capacity of up to 10,000 Amorphous Silicon (ASi) detector panels per year from PerkinElmer Optoelectronics’ 60,000 sq-ft facility, digital x-ray photography is for the first time practical for industrial, scientific, and commercial applications. "Now engineers can actually see the inner workings of their designs," says PerkinElmer’s Business Development Manager Don Lake. "Without the usual hassles associated with lining everything up."
Produced at the largest ASi facility in the world, the RID 1024-400 monolithic digital x-ray camera lets engineers analyze everything from pipelines to airplane wings, load bearing structural members to printed circuit boards, breakfast cereal boxes to delivery vans, or even the inner workings of a fuel pump during operation. The 41 X 41 cm detector coupled with its mega-pixel spatial resolution and 65,000 gray scale detectivity produces images not only superior to x-ray film, but impossible to achieve with film. "This is the largest monolithic structure ever produced in the world, as far as we know," says Lake. "Large is better for the detector because it can catch the desired image over a wider tolerance of position."
Superior sensor area size, resolution and detectivity in an x-ray digital camera leads to several advantages:
- Clear and sharp image details across the sample, with 65,000 gray scales that allow engineers to see throughout the density profile of the subject, from top surface to bottom surface and anywhere in between.
- Electronic zoom allows analysis of any region of interest.
- Electronic processing delivers the exact image desired. With a complete image available for viewing in less than half a second, the engineer can determine if the captured image is the desired one, and if not, take any number of others without having to once again pose the subject.
- Live digital images at 3-5 frames per sec.
- Electronic capture is Internet-compatible. Within seconds, the x-ray images can be sent anywhere in the lab, or the world. Expert analysis can be done in real time no matter when or where.
- Full-size x-ray image capture is portable and adjustable. Because the RID 1024-400 is only 5-cm thick and less than 20 cm larger than the detector, the camera is easily transported, and once there, is easily positioned.
- High sensitivity allows lower x-ray doses, reducing the potential dangers of overexposure.
- The RID 1024-400 images are compatible with all image analysis software and all PCs. Scientists, engineers, and analysts can thus quickly and easily upgrade to full-sized x-ray image capability.
The detector is based on an ASi sensor operating as a two-dimensional photodiode array. The 41 X 41 cm2 photoactive region has 1,048,576 discrete photodiodes arranged in 1,024 X 1,024 pixels on 400µm centers. X-rays are converted to light using a Lanex® fast or Csl scintillator. The detector performs digital image acquisitions, and has all drive and readout processing electronics (lead shielded), including an x-ray interlock.
The detector’s digital output is transferred via a parallel interface card that plugs into a PCI slot in a PC. Shipped with 100-ft of cable and HIS (Heimann Imaging Software) for acquisition and demonstration, the detector weighs 60 lb. Price is approximately $60,000.
Waterproof bonding helps hulls
Peoria, IL--The latest trend to sweep the small pleasure boat industry is a hull protector.
Sue Rogers-Smith grew up playing around on small power boats and Jet Ski-type personal watercraft. She noticed that fiberglass hulls took a beating every time someone dragged them up on a sandy beach, or banged them around a trailer being towed down the highway. Over time, the scrapes and gouges can destroy a boat, as fiberglass soaks up water and eventually starts to leak.
So she bought sample polymers and plastics from companies like Dow and BASF, and started experimenting with ways to attach the material to the bottom of a boat, forming a flexible, waterproof armor plating. And in 1994, the third-generation State Farm agent quit the insurance business to start KeelShield™ Inc.
The grooved top layer of KeelShield is a polyurethane elastomer, bonded in a proprietary process to a two-sided adhesive foam tape. A plastic cover peels off the sticky side of the tape.
Her discovery: a way to bind Dow's Pellethane™ thermoplastic polyurethane (TPU) elastomer to a fiberglass hull. She uses 3M's VHB™ tape to create a bond that will not degrade despite long-term underwater immersion. How does she do it?
"It's a trade secret how I marry the substrate to the adhesive," says Rogers-Smith. The adhesive is dispersed throughout a 45-mil thick, two-sided, acrylic foam tape, which adheres to any surface but the untreated TPU, Rogers-Smith notes. Her secret is in the treatment of the urethane as she applies the tape.
KeelShield is attached as a five- or 12-inch wide stripe down the center of a boat's hull, covering the ridge at the bottom. A 20-foot boat would need about seven feet of protection, she says. And far from slowing down, a Jet Ski with KeelShield can go 0.5 to 1 mph faster than an untreated craft, because ridges in the KeelShield channel water to the engine intake, Rogers-Smith claims.
Today this garage start-up company employs five people, and contracts its TPU embossed extrusion jobs to an unlikely source--the St. Louis, MO factory of athletic goods company Nike. This sporting goods factory can handle the job because it has the latest extruding equipment, also used to make its shoe soles and the air bags that provide the cushion in Nike Air running shoes. Then Nike sends her the "dry" KeelShield in 15 different colors, and Rogers-Smith and her four employees do their secret adhesive-bonding process, before shipping the finished product out to boaters worldwide.
Today her company is growing at a pace that sees sales double each year, and it just signed up a European sales office. Future applications will be seen on boat decks, she says.
Wizard conjures Turck sensors
By Benjamin B. Ames Associate Editor
Proximity sensors are solid-state electronic devices used as alternatives to mechanical switches, often in production line applications.
Turck Inc., a long-time producer of these sensors, is now taking its products into cyberspace. Turck announced a relational database version of its sensors and cordsets catalogs, located online at a www.turck.com. Aimed at mechanical engineers, Original Equipment Manufacturers (OEMs), and Turck's sales and distribution teams, the site is designed for sensor search and selection.
Users can select a sensor appropriate for their application, add it to a "purchase requisition," and submit that to their nearest sales office for a quote. Dubbed the TIP (Turck Internet Product) Wizard, the site boasts several features not available in the catalog's print version. With the Sensor Attribute Search function, an engineer can specify the appropriate sensor technology needed, and the site will respond with a list of associated attributes. Or the engineer can define the attributes needed, and the site will give a list of matching part numbers. Once the engineer's found the right product, he or she can view a dimensional drawing or wiring diagram before making an order.
Since the information is stored in a relational database, the online catalog is dynamic, so it will immediately reflect any changes such as new products or prices. Turck worked with the Banta Book Group and Millstar Electronic Publishing Group to create the database and site.
"Please, Mr. (Electric) Postman..."
Washington, DC--The U.S. Postal Service has selected Ford Motor Co. (Dearborn, MI) and Baker Electromotive (Rome, NY) to supply it with 500 electric mail-delivery vehicles. Production will start at Baker Electromotive's plant this fall. The order is the single largest electric vehicle order in U.S. history and it may grow to a total of 6,000 vehicles.
The vehicle will consist of the Ford Ranger EV chassis with a Grumman body. One unique feature Ford highlights is a pre-heating system that heats up the vehicle interior while charging. Heating energy is taken from the power grid rather than the battery, thus not taxing the charging cycle or range.
John Wallace, Ford's executive director of its TH!NK Group says, "The shorter, more predictable routes make the Postal Service the perfect customer." The electric vehicles will be used in California and the Washington, DC area.
National Engineering Week may be over, but the kid in all of us can check out a site that takes a look at the wonderful world of engineering. The site is designed for middle-school-aged children, and there are videos clips about repairing satellites and CAD; information on what it takes to design a jet; how to make plastic in your own kitchen; or play a rousing game of Techno-babble, a Jeopardy™-like game on the site. Head over to http://www.discoverengineering.org and check it out.