Aircraft designers look to 'wired wings'
What would automobile travel cost if cars needed ten man-hours of maintenance for every hour of driving? It's not really a fair comparison to the figures for flying--a breakdown on the road isn't as worrisome as one aloft--but the heavy maintenance needs of conventional aircraft present a crushing economic burden on military and civilian flight.
Engineers grappling with aircraft maintenance difficulties have targeted hydraulic systems as especially troublesome. Although hydraulic systems' power-to-weight ratios still reign supreme, sources say that advanced power-switching electronics and electric motors may soon supplant hydraulics in aircraft flight-surface-control and utility applications.
The potential benefits from a change to electric actuators on aircraft? "Reliability, maintainability, supportability, and lower life-cycle cost," answers James Cloyd of the Air Force's Wright Lab- oratory. Advances in electronic components should give electric actuators greater mean-time-between-failure than hydraulic designs. Self-contained electric actuators would be line-replaceable units. Eliminating hydraulics reduces the need for specialized ground-support equipment and personnel. And, an electrically operated aircraft would have a shorter logistics "tail:" that is, fewer fluids, solvents, and lubricants; and fewer environmentally hazardous spills to clean up.
What this means to you
Electronics may replace hydraulics in aircraft and elsewhere
Lighter, more-reliable, and more-easily repaired aircraft designs.
Cloyd serves as chairman of the U.S. government's More-Electric Aircraft initiative, a series of R&D programs looking into electrifying every aspect of aircraft power requirements. "The strategy is to demonstrate technology on existing aircraft to solve real problems today," he says, "as well as to encourage spinoff of technologies to a variety of other industries." Finding answers to power-delivery problems should create demand in commercial aerospace, manufacturing, and electric-vehicle industries that will eventually drive down the cost of electronic components for military aircraft.
Work on electric actuators and power supplies has been going on for more than ten years. Prototypes flew in the mid '80s on an Air Force C-141, the so-called High-Technology Test Bed C-130 in 1990, and the Electrically Powered Actuator Design Validation F/A-18 in 1993.
Development centers on two types: electromechanical actuators (EMA) and electrohydrostatic actuators (EHA). Curiously, it's the EHA design, where an electric motor powers a self-contained, fixed-displacement hydraulic pump and actuator, that seems to have the upper hand. The reason concerns reliability.
In the event of a malfunction, "an EHA can be by-passed and returned to a previous position," explains Jim Ryder of Parker Bertea's Control Systems Div., Irvine, CA. "The jamming solution requirement hasn't been overcome in the EMA. I don't know of any solution that's acceptable to the prime contractors, the government, or the FAA."
Design work continues because hybrid electrohydrostatic actuators raise unique concerns of their own. "One of the technical challenges is having to dissipate a lot of heat," explains Scot Schaefer, director of Moog, Inc.'s technology center in East Aurora, NY. The relatively large fluid volumes of conventional hydraulic systems serve as an effective heat sink. But an EHA and its power supply require auxiliary heat-transfer apparatus that adds to their weight and partly negates the weight savings electric-actuation proponents count on.
Other issues, like leaks from the EHA's reduced hydraulic reservoir, lower power-to-weight, and longer response times, seem less of a concern. Parker's Ryder points to improved, redundant seals and the simplified replacement of self-contained units. And Moog's Schaefer feels that dealing with EHA's dynamics will become easier with experience. Those problems may pale beside the overall benefits of replacing an airplane's central hydraulic system. "The savings are in the plumbing, not the actuators," says Schaefer.
Cloyd agrees. The More-Electric Aircraft (MEA) initiative's Joint Planning Team has identified four technologies vital to changing the way aircraft look, fly, and are maintained: a starter/generator integrated within a turbine engine to eliminate geartrains and permit the use of magnetic bearings (see Design News, 3-28-94, p.40); electric primary flight-control actuators; an integrated auxiliary power unit with battery or compressed-air start; and a fault-tolerant power management, distribution, and motor-control system. Plans call for a first-generation MEA to fly in 1998 and a second-generation aircraft, with the embedded generator and distributed power and control systems, by 2008.
Aircraft designed along the lines of MEA would be slimmer, faster, and have longer range. "In the long term, MEA would be almost autonomous in the logistics sense," says Cloyd. For civilian aircraft, these benefits would translate into lower ownership costs. For the military, easily deployable, more-reliable aircraft allow getting more done with fewer resources. That's a goal worth pursuing, because, as he explains, "We know there will be manpower reductions, but our job of defending the nation won't go away."
Recent advances in high-temperature power electronics bolster prospects for more-electric aircraft. This silicon-carbide-based op amp withstands temperatures to 500°C.
Achieving the weight and cost savings envisioned for the Air Force's More-Electric Aircraft requires a near-complete elimination of fluid power in the aircraft.
Moog, Inc. developed this triplex redundancy-management scheme for tandem-pump EHAs. Third, or model, controller channel arbitrates disagreements between other channels.
Parker Bertea's self-contained electrohydrostatic actuator reflects 10 years of design work. Note the extensive heat sinking around the high-pressure reservoir.
--Terrence P. Lynch, Northeast Technical Editor
Bearing maker cleans up cleaning process
Peterborough, NH--New Hampshire Ball Bearings (NHBB), Inc. has installed a new process that allows it to satisfy ongoing requirements for contamination-free parts, while also meeting stringent environmental standards.
The non-ozone-depleting (NOD) process removes oils and particulate matter from its high-precision ball and roller bearing assemblies. NHBB customers require the ultra-precise components for such applications as aircraft engines and airframes, medical devices, machine tools, and computer components.
NHBB weighed several options before settling on the Advanced Vapor Degreasing (AVD) process. The first option considered to replace the 1,1,1,trich-loroethane and chlorofluorocarbon (CFC) compounds used in the cleaning process involved water-based cleaning. While it seemed appropriate for certain bearing components, completely assembled bearings proved incompatible with the process. Water droplets deposited by the aqueous cleaning could trap contaminants, displace lubricants, and degrade bearing performance.
Semi-aqueous cleaning of assembled bearings also was investigated. However, the alcohol dewatering agents raised added safety concerns and were rejected.
The non-aqueous AVD cleaning method, developed by Petroferm, Inc. in cooperation with 3M, uses non-ozone-depleting cleaning and rinsing agents to remove the oil and particulates. The process employs a two-sump, batch-cleaning system and two liquids, a solvating agent and a rinsing agent. Cleaning with AVD involves immersing the parts in a boil sump containing the two agents.
After a boil cycle of about two minutes, the parts basket is transferred to the adjacent rinsing sump. Here, the rinsing agent displaces both the solvating agent and its dissolved oily contaminants. The lower-density, contaminated solvating agent quickly rises to the surface of the rinse sump, where it is carried back to the wash sump as overflow.
Non-ozone-depleting process allows New Hampshire Ball Bearings to clean its high-performance parts without any fear of residual contamination.
Color concentrates give Brother a competitive edge
Bartlett, TN--For years, Brother Industries, U.S.A., Inc. relied solely on outside molders to process its business-machine components, primarily using pre-colored HIPS and ABS resins. But with growing competition, Brother determined that it was vital to lower resin costs.
Therefore, in the early 1990s, Brother began exploring the option of using natural-base resins, plus concentrates, as an alternative to pre-colored resins. To help bring this about, the company initiated a process of tight-tolerance color matching and sampling. Experience gained at these trials showed that concentrates not only exhibited excellent color capabilities, but were more efficient to inventory and less expensive than the pre-color alternative.
The results contributed to Brother's decision to invest more than $3 million to build a large molding operation, complete with four injection-molding machines, silos, cooling towers, and state-of-the-art color-blending equipment. In August 1992, the company began its own molding operation--with a reduced reliance on outside molders. Then, in the fall of 1992, it switched all of its molders of HIPS-HB-grade polystyrene to natural, with the concentrate supplied by ReedSpectrum, Holden, MA. The next year, Brother shifted its ABS coloring to concentrates as well.
Benefits derived from the natural concentrate formula:
Base resin-material costs went down due to an increase in purchasing power for one resin, plus concentrate, vs. the high cost of purchasing numerous pre-colored, same-base resins.
Brother's Kirby model word processors benefit from the use of color concentrates for many of their key components.
Insulated powders boost motor efficiency
Emporium, PA--Engineers at Pennsylvania Pressed Metals (PPM), Inc. are replacing laminated steel with insulated iron powders. In electromagnetic applications where constant magnetic permeability and low core losses are required, engineers say, Ancorsteel® Insulated Powders (IP) from Hoeganaes Corp., Riverton, NJ, can reduce cost and improve efficiency.
The powders use a non-conductive thermoplastic polymer coating that makes them suitable for ac applications, according to William Michael, Hoeganaes sales and marketing vice president. For example, PPM engineers recently replaced a low-carbon steel positioning grid with SC-120, which offers the best permeability of the Ancorsteel line of powders.
The grid provides a magnetic path for a positioning motor in a panel printer. Its complex geometry made laminated steel an impractical choice, explains materials and process development manager Ryan Sun. "It's a fairly large part, and the concern was that heat build-up would reduce the motor's efficiency," says Sun.
Although the grid was converted to IP from machined cold-drawn steel for cost savings, the new design also improves efficiency and provides low eddy current loss, says Sun.
IP also is improving the housing of a small electric motor. Machining the tube-shaped housing from bar stock laminated steel would be prohibitively expensive, Sun says. Instead, engineers chose Ancorsteel TC-80, which offers the lowest core losses of the IP series.
After molding, the part is thermal-treated and secondary machined. The part's final density is 7.0 -7.2 g/cm³. The design improves the motor's efficiency, and allows engineers to create several parts and assemble them to make a longer housing, adds Sun.
Powders treated with a non-conductive coating yield insulated parts such as this housing for a small electric motor.
Data exchange gets products moving
Kitchener, Ontario--For Apex Metals of Kitchener, Ontario, designing small- to medium-sized stampings for companies like Ford, Chrysler, Honda, and Toyota is no easy task. To ensure precise control over their designs, Apex engineers use CATIA 3-D CAD software.
The main benefit of a 3-D environment, says Harry Tempelman, engineering CAD-CAM supervisor at Apex, is that a designer always knows exactly where he or she is in space. "It is much more difficult to visualize a design when it's flat or in 2-D," he says. "With 3-D we have much more control." Apex runs CATIA on an RS6000 workstation, and has an Electronic Data Interchange set up with some of its customers, including Chrysler.
3-D design has also proven useful when presenting proposed designs, by enabling customers to better visualize how a part will work. In the past, say engineers, this kind of understanding was sometimes only possible after a part was already manufactured.
When making 3-D presentations in the customer's location, Apex avoids tying up a CATIA workstation on site by bringing along a portable PC. Originally, moving CATIA files to this PC was difficult because of severe limitations on sending CATIA files to a printer or other output device. Tempelman solved the problem with CadDesign, a file-conversion package from Tailor Made Software, Kent, WA.
CadDesign moves CATIA files from the AIX operating-system environment to a TIFF or GIF format. By adding CadDesign to the computer set-up, Apex can now move CATIA files to an IBM 700C PC for in-person meetings, or send a digital file to a customer site where it is loaded into that company's DOS system.
When designing this automotive gear shift lever for Chrysler, engineers at Apex Metals used CadDesign software to translate the 3-D model from a CATIA file to a format useable on PC platforms.
MEs, EEs design in harmony at Peavey
Meridian, MS--Engineers at Peavey Electronics are applying modern computer technology to bring speed and efficiency to an ancient art: designing musical instruments.
"We're in an incredibly competitive and fast-moving market," says spokesman Jere Hess. "We introduce more than 100 new products every year, and many have a life-cycle of six months or less."
CATIA software, developed by Dassault Systemes and sold by IBM, helps engineers simulate parts on screen, do interference checks, and determine inertial and mechanical constraints. And, by doing "virtual prototypes," Peavey engi neers have cut up to two months off their development time. "Now, we do one or two engineering prototypes, and we're done," says Drew Goodman, mechanical engineering supervisor. Before using solid-modeling software, engineers needed an average of six physical prototypes--each taking two weeks.
CAD is also helping mechanical and electronic engineers at the company to work together concurrently on a project--and remain in synch. For example, while the mechanical design team creates a physical box for speakers, amps, and other products; an electronic design team creates circuit boards to go inside. Electronics engineers share their 3-D files from a specialized program with the mechanical engineers. The files are imported into CATIA, providing basic "footprint" information about the number of circuit boards in a product and their size, as well as mechanical components. This ensures that the finished "box" will leave adequate room for the electronics, and allows the EEs to do most of their complex designs while the MEs complete their housing design.
"This is no small accomplishment," Goodman says. "Our circuit boards have to be housed properly, with just enough clearance and elements such as input/output jacks lined up precisely. If we had to take hard-copy line drawings and recreate them in our CAD program, we couldn't be sure of this."
GE Fanuc, Microsoft aim to simplify 'mass customization'
Redmond, WA--A new line of factory automation software from GE Fanuc (Charlottesville, VA) may help design engineers address the increasing demand for "mass-customized" goods. Called CIMPLICITY® Monitoring and Control Products, the programs are "the industry's first and most powerful line of factory-automation software products designed for and fully compatible with Windows 95 and Windows NT technology," claims Bob Collins, CEO of GE Fanuc.
The CIMPLICITY line consists of four products: MES/SCADA, MMI, Control, and Motion. They handle everything from enterprise-wide process monitoring and supervision to motion control.
"CIMPLICITY Windows-based tools can automatically integrate the configuration and programming of all automation equipment on the factory floor," says Collins. "Cycle times for product changeovers can be shortened from months to days."
The greatest benefit these products offer design engineers may prove to be in mass-customization. This involves manufacturing a wide variety of products in small quantities but large overall volume, to meet increasing customer demands for unique products. And while computerization of the engineering department has simplified the task of creating mass-customized designs, manufacturing departments have found themselves hampered by the limits of incompatible and difficult-to-use factory-automation systems.
Engineers, comfortable with the look and feel of Windows programs on their home and office desktops, pushed for the same benefits in the shop, both companies say. "We expect such industrial solutions to grow to a billion-dollar business in the next two years," says Pieter Knook, Microsoft's general manager for enterprise solutions.
--Mark A. Gottschalk, Western Technical Editor
Gesture-recognition system may give CAD a hand
Palo Alto, CA--Virtual Technologies Inc. has designed a gesture-recognition system that could pave the way for CAD users to rotate on-screen computer objects with hand motions in the air.
Called GesturePlus, the device is built around a standard PC running DOS. It connects to a data-input device, such as the company's own CyberGlove, and via serial port to a software application. By using a complex series of algorithms, the system takes data input from the glove and determines what gesture has been made.
Users must first "train" the GesturePlus system to recognize various gestures. For example, touching three fingers together could be "pick," and a 180-degree turn of the hand could be "rotate." The user decides on the gestures desired for varoious commands, and inputs them into the system. Once that information is stored, it can then be used in an application set up to support GesturePlus.
R&D engineer Sidney Fels says GesturePlus makes it easier for software developers to incorporate gesture recognition in mainstream CAD applications. Using just the CyberGlove, software developers had to write their own recognition algorithms. "This is the next step to free up the application programmer from having to understand the data," he explains. Virtual Technologies has developed a prototype CAD demonstration which uses the GesturePlus and CyberGlove systems to "understand" a user's hand movements. Company officials hope that commercial CAD software will adopt the technology as well.
GesturePlus is scheduled to begin shipping in November at $3,500 through the end of the year.
GesturePlus, a 'virtual device,' interprets gesture data coming from a variety of sensing devices such as a data glove. The system transmits the name of a recognized gesture, such as 'rotate,' to a host computer. CyberServer hardware allows a host computer to communicate with numerous devices over a single high-bandwidth communication channel.
Software saves John Deere nearly $500K/year
Waterloo, IA--Engineers at John Deere Engine Works say that Design of Experiments software (DOE) has saved them nearly half a million dollars annually by helping them recognize the need to eliminate chromate conversion from their aluminum parts. The software revealed that the expensive additive is not a significant factor in paint adhesion.
DOE is an approach to experimentation that considers all variables simultaneously. It shows how interconnected variables respond over a wide range of values, without requiring all values to be directly tested.
To carry out their testing, John Deere Engine Works chose Design-Ease® software from Stat-Ease Inc., Minneapolis, MN, as their DOE approach. "Design-Ease offers the capability to show engineers real-world results," says Supply Management Engineer Wayne Mills. "It helps us understand what's happening without spending days trying to understand the mathematical theory.'
DOE allowed them to test 12 variables in a week, compared with traditional methods that would have tested only five variables in two weeks. John Deere soon narrowed variables down to three: chromate conversion, paint type, and surface treatment. A 3-D cube plot generated by the software showed how the three variables interacted, proving that paint type is the major factor in paint adhesion.
Mills feels that the greatest benefit of DOE is design optimization. "We can design the parts better, at lower cost, and faster using Design-Ease up front during design and development, rather than discovering we have a problem when the part is already out in the field."
Composite aids appearance and assembly speed
Stamford, CT--Good looks were only part of the equation when engineers needed to select a material for the paper-feed deck of the new Pitney Bowes Midrange mailing machines. The part also had to have high strength and stiffness. Designers found the right combination in a glass-fiber-reinforced polycarbonate composite with an internal lubricant.
"The deck is where you place a letter or package to feed it into the machine," explains Bob Reid, a technical advisor at Pitney Bowes. "It's a part that should be pleasing to the eye."
Reid got that ingredient in Lubricomp® DFL with a PTFE lubricant from LNP Engineering Plastics, Exton, PA. "The composite certainly provides an excellent surface finish," Reid adds. "However, it's the underside of the deck, the part that you don't see, where the material really makes the difference."
The underside supports much of the machine's internal components. "It's actually a housing for complex parts, such as rollers, gears, and motor mounts," he explains. "The PTFE lubricant and glass-fiber reinforcement of the DFL material yield the low-wear friction, strength, and stiffness needed to support the large number of bearings, tabs, and sliders in the deck."
The material's mold-flow technology also yields a complex-part geometry that fills out completely. "Previously, when we used metal for the decks, we'd take a piece of sheet metal, make individual parts, and then spot weld them together," Reid adds. "Now that we use a plastic composite, we can mold all of these parts into a single unit."
BASF backs education foundation
Mount Olive, NJ--With a $10,000 donation, BASF Corp. becomes the latest addition to the list of top companies supporting the non-profit Design News Engineering Education Foundation. The money will help fund scholarships to the engineering schools chosen by the recipients of the Design News Engineering Achievement Awards.
"The foundation of BASF's success in meeting the needs of our customers is a commitment to technical excellence," says Dr. Reinhard Katz, vice president, BASF Plastic Materials. "The awards program is a part of BASF's education effort, which also includes partnering with OEMs."
With worldwide headquarters in Germany, BASF produces a broad line of engineering materials, including acetal copolymers, nylons, PBT thermoplastic polyesters, styrenic copolymers, several high-performance thermoplastics, high-density polyethylene, and polyurethane automotive suspension products.
Among the key application areas for these materials are: automotive, electrical/electronic, medical equipment, sports equipment, and packaging.
As BASF sees it, technological advancement in materials continues to move very quickly. So, OEMs today must rely on their suppliers for technical support. "It is extremely difficult, if not impossible, for OEMs to be experts on every technology that exists," says Katz. BASF supports engineers through their plastics applications centers in Wyandotte, MI; Germany; England; Spain; Japan; and Australia.
These centers are equipped with the latest computer modeling and analysis tools and can simulate processsing conditions to point out potential trouble spots with designs before tooling begins. BASF plastics processing facilities enable customers to evaluate molds and prototype parts. The customer design and processing seminars cover all elements of application development, including material selection, part design, computer-based flow and structural part analyses, and part and process optimization.
With partnering as a basic way of life at BASF, Katz finds that an optimum combination of state-of-the-art technologies from around the world are used to develop new products. The results: reduced development time and easier development.
For example, the Cadillac's Northstar® engine is the first air intake manifold for a V-8 engine to be made in North America using the melt-core injection molding technique. A key strength brought by BASF to this project is its long history of helping automotive companies successfully develop air intake manifolds.
Truck firm turns to stainless-clad aluminum for longer-lasting bumpers
Chicago--Navistar International has become the first major truck manufacturer to offer stainless-clad aluminum as a bright bumper material option on its aerodynamic International® class 8 models. The company chose the material over chrome-plated aluminum because of its "proven reputation for appearance, durability, long-term corrosion resistance, and environmental friendliness."
Texas Instruments, Engineered Materials, Attleboro, MA, developed the bumpers. In earlier tests conducted by Robert Baboian, TI principal fellow, the material withstood rough, long-range trucking conditions for up to 1 million miles without losing its bright appearance. The stainless surface does not rust, peel, or spall, even when hit by stones and other scrapes trucks encounter in heavy-duty service. The bumpers, according to Baboian, have survived severe bend damage and repair without corrosion. And they are anywhere from 30-40% lighter than the chrome-plated counterparts, he adds.
Texas Instruments attributes the improved durability to a 0.004-inch-thick surface layer of stainless steel clad to aluminum. The metal bond is at the atomic level, making the materials inseparable. By comparison, nickel-chrome plate on conventional bright aluminum bumpers measures less than 0.002 inch, resulting in a weaker plating bond.
Texas Instruments achieves the bond using a refined process based on solid-state welding technology. The bonding is so effective, says Baboian, that there is no need for intermediate brazing alloys or adhesives.
Virtually any combination of ductile metals can be clad, with individual components representing from 2% to 98% of the total composite thickness. As a rule of thumb, composite properties, such as tensile strength and conductivity, can be estimated as the arithmetic sum of the volume percent of each component times its specific property value. Dimensions of TI clad metals range from 0.001 to 0.150 inch thick, and up to 24 inch wide.
In switching to the stainless-clad aluminum, Navistar engineers stress that the steel-clad bumpers are not more expensive than the chrome-plated version. The switch also enabled Navistar to eliminate shipping and handling costs associated with sending the part to platers several hundred miles away for processing. And, as an added side benefit, eliminating the plating operation made only one supplier fully accountable for the bumper's production.
Stainless-clad aluminum bumpers give aerodynamically designed Navistar International trucks protection from corrosion and other damage.