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November 2, 2003-- This article summarizes several papers presented at the 2003 SAE World Congress in Detroit in March, and includes other information about advances in automotive materials.

*Aluminum in SUV raises safety, reduces weight

Two studies released by the Aluminum Association, Southfield, Mich., are said to show that reducing weight in Sport Utility Vehicles (SUVs) by selecting aluminum for more applications also improves safety and fuel efficiency. The two studies were presented by engineers from Ford Motor Co. at the 2003 SAE World Congress in Detroit. One paper evaluated the design of an aluminum SUV frame, and the other reported on the development of a unitized aluminum SUV body.

The aluminum frame was developed as part of a joint government/ industry research program to study the capability of an aluminum frame to achieve equivalent performance to the 2002 Ford Explorer steel frame. According to the report, the aluminum frame weighed 40% less, yet was equivalent in performance to the traditional steel frame.

The aluminum body study was part of an advanced research project to determine the feasibility of a high-volume, lightweight SUV that would be suitable for the new "City SUV," a low-profile vehicle that would have the ride characteristics of a sedan. Ford produced ten bodies-in-white, of which eight were transformed into complete SUVs. The study showed that the aluminum body weighs 50% less than the steel body.

For more information: Aluminum Association, One Towne Square, Suite 230, Southfield, MI 48076; tel: 248/784-3005; fax: 248/784- 3006; Web site: www.autoaluminum.org.

*Aluminum Explorer frame cuts weight by 40% compared with steel

A lightweight aluminum sport utility vehicle (SUV) frame was designed by Ford Motor Co. with the support of Alcan Aluminum Corp. and The Budd Co., as part of the joint government/industry Partnership for a New Generation Vehicle (PNGV). The project was the subject of a paper presented at the 2003 SAE World Congress, titled "A Design Concept for an Aluminum Sport Utility Vehicle Frame (SAE paper 2003-01-1101)," by Michael W. Danyo, Christopher S. Young, Henry J. Cornille, and Joseph Porcari, of the Ford Motor Co., Dearborn, Mich.

A study was carried out at Ford to assess the capability of an aluminum frame to achieve equivalent performance to the 2002 Ford Explorer steel frame, but at a 40% weight reduction. Image courtesy Ford Motor Co.

The specific objective was to assess the capability of an aluminum frame to achieve performance equivalent to that of the steel frame in the 2002 Ford Explorer, but at a 40% weight reduction. The four goals were:

* Define a package space for the new aluminum frame that is compatible with the 2002 four-door Explorer.

* Reduce weight by 40%.

* Provide equivalent stiffness, durability, and safety.

* Define a manufacturing process.

Engineers determined that if the dimensions of the aluminum side rail sections were slightly increased, then the aluminum frame would match the steel frame in static bending and torsional stiffness. It would also probably have excellent energy absorption during frontal impacts.

Three methods for the assembly of an aluminum frame were evaluated. One method involves mainly MIG welding, which joins the steel frame. However, because the thermal conductivity of aluminum is 11.5W/m-K and that of steel is 3.9 W/m-K, it was decided that the process selected must minimize the amount of MIG welding to reduce distortion.

The second proposal was a one-piece hydroformed side rail, which would reduce the number of parts required and eliminate 45% of the MIG welding in the frame. However, the variety of section sizes required may fall outside the capabilities of hydroformed aluminum tubes. In addition, such tubes must be MIG welded to the side rails.

The third proposal is based on self-piercing rivets and adhesives. The adhesive/rivet joint bonds the rail inner and outer, and eliminates most of the MIG welding and its associated distortion.

For more information: SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001; tel: 724/776-4841; fax: 724/776-5760; Web site: www.sae.org.

*Titanium coil springs have low density, low elastic modulus

A low-cost beta titanium alloy specifically designed for automotive coil spring applications was discussed in a paper presented at the 2003 SAE World Congress. Titled "Properties and Production Experiences of Timetal LCB for Automotive Spring Applications," it was prepared by Yoji Kosaka and Stephen P. Fox, Titanium Metals Corp., Henderson, Nev. The alloy has low density, low elastic modulus, and excellent corrosion resistance.

Applications of titanium to automotive parts have been considered for the last 20 years. Titanium connecting rods, valves, and springs have frequently been used in racing and aftermarket applications. In particular, titanium suspension springs offer many technical advantages, and progress has been made in achieving both low cost and properties that should meet the requirement of spring and automotive manufacturers. For example, LCB springs can be wound on the same equipment as that for steel springs.

The shear modulus of beta titanium alloys is almost half that of steel, enabling a 20% smaller size than needed for steel springs. As a result, a weight savings of 40% was reported in the Volkswagen Lupo FSI when steel springs were replaced with Timetal LCB alloy.

Timetal LCB has recently been successfully applied in research settings by production routes and processing methods that can be translated to a larger scale. However, the cost of titanium must be reduced to expand the applications of titanium suspension springs to mass production vehicles.

For more information: Yoji Kosaka, Titanium Metals (Timet) Corp., Henderson, NV 89009; e-mail: yoji.kosaki@timet.com. Circle 296

*Lost-foam casting makes complex magnesium automotive parts

The lost-foam or expendable pattern casting (EPC) process is capable of making extremely complex part shapes at low cost, according to a paper presented at the 2003 SAE World Congress. Titled "Developments in Lost Foam Casting of Magnesium," the paper was prepared by Michael Marlatt, WFV/Roeperwerk; David Weiss, Eck Industries Inc., Manitowoc, Wis.; and John N. Hryn, Argonne National Laboratory, Argonne, Ill. The paper describes a project in which the American Foundry Society (AFS), Magnesium Division 6, cooperated with industry members to develop lost-foam casting methods as alternatives to the conventional high-pressure die casting and precision sand casting methods.

Compared to lost foam casting processes, disadvantages of the conventional processes are that casting design geometries are limited. Complex designs cannot be produced by the steel die sections, and are limited by moving cores of die cast tooling. On the other hand, a major advantage of the lost foam process is the ability to create a single complex component that can replace several fabricated components.

Standard test shapes were chosen to determine the ability of the magnesium to fill the mold and to evaluate the types of defects encountered. The paper explains how this project evolved, including the developmental strategies, the products selected, the casting trials, and the casting results. Major factors in the study included a lost foam material and pattern, a pattern coating material, a molding sand type, and an alloy type.

The casting trials were held at Eck Industries, where several hundred pounds of AS91E alloy were melted by standard magnesium melting practices with SF6 cover gas for melt protection. Visual examination of the first castings showed that successful lost foam casting of magnesium is possible. X-ray inspection confirmed this result, and then the castings went through a T6 heat treatment cycle prior to evaluation of mechanical properties.

These trials proved that casting magnesium via the lost foam technique can be successful when good foundry practices are followed closely. This is also true for the safety aspects of casting magnesium in a foundry environment.

For more information: David Weiss, Eck Industries, P.O. Box 967, Manitowoc, WI54221; tel: 920/682-4618; fax: 920/682-9298; e-mail: dweiss@eckindustries.com; Web site: www.eckindustries. com. Circle 297

*Semisolid method produces high-integrity aluminum castings

The semi-solid metal (SSM) casting process and potential applications were discussed in detail in a paper titled "The Use of Semi-Solid Rheocasting (SSR) for Aluminum Automotive Castings," presented at the 2003 SAE World Congress. The authors were James A. Yurko, IdraPrince Inc., Holland, Mich.; and Raul A. Martinez and Merton C. Flemings of MIT, Cambridge, Mass. Semi-solid casting is an alternative forming process in which high integrity castings are produced in a conventional die casting machine. Unlike conventional processes, semi-solid casting is based on partially solidified aluminum or magnesium alloys possessing a nondendritic, globular microstructure. Several process advantages are derived from combining these two characteristics:

* Solidification shrinkage is reduced because the alloy has undergone a partial phase transformation outside of the die cavity\.

* Solidification time in the die is decreased because of the reduced latent heat.

* Planar front filling speed of the die is faster because of the higher-viscosity, non-Newtonian fluid flow behavior.

* Thermal fatigue of the die is reduced because of reduced thermal shock.

These advantages result in high-integrity, heat-treatable castings produced at cycle times that are comparable to or faster than die castings. They are near net shape, of complex geometry, and can possess thin and thick walls in the same part.

Previous and existing semi-solid processes have had limited commercial acceptance because of cost and processing issues. However, a new semi-solid process, originated at the Massachusetts Institute of Technology, and now under development by IdraPrince, eliminates these barriers. Now known as SSR, for semi-solid rheocasting, the new method creates semi-solid slurry quickly and efficiently from molten alloy.

Semi-solid processing has two major classifications: thixocasting and rheocasting. In thixocasting, specially prepared alloy is reheated from ambient to the semi-solid forming temperature before casting. In rheocasting, a liquid alloy is modified into a semi- solid slurry, and then is directly formed at the foundry.

Through the end of the last decade, thixocasting accounted for about 14,000 tons of aluminum castings worldwide, less than 1% of all aluminum casting. Rheocasting eliminates the disadvantages of thixocasting, and has the following advantages: Ordinary foundry alloy is used; the scrap can be recycled; and alloy selection is limitless.

Furthermore, experiments have shown that SSR is robust, and that large variations of stirring time, stirring speed, and starting melt temperature have little effect on the sphericity of the semisolid particles.

For more information: James Yurko, IdraPrince Inc., 670 Windcrest Drive, Holland, MI 49423; tel: 616/394-8287; e-mail: jayurko@idraprince.com; Web site: www.idraprince.com. Circle 298

*Foam-core carbon fibers build lightweight vehicle space frames

Foam cores covered with braided carbon fiber sleeves have reportedly been designed for building up vehicle structures by Coretex Structures Ltd., U.K. The structures can be built up automatically within a preformed low-cost mold to form vehicle space frames, truck chassis assemblies, or vehicle trailers. Metallic inserts may be integrated as required. The assembly is impregnated at 60[degrees]C (140[degrees]F) under vacuum, and bonded with a low- viscosity, tough, two-part epoxy. The foam core expands under vacuum, improving fiber alignment and increasing interior volume.

Coretex structures are said to offer stiffness similar to automotive steels, with higher failure strength, at less than 40% of the weight of steel. Furthermore, the material fails in a progressive and controlled manner during collision, and the foam core passes automotive flammability tests.

For more information: Steve Cousins, Coretex Structures Ltd., Turing House, 1 Southbridge Grove, Kents Hill, Milton Keynes, MK7 6HW, England; tel: 44 1908-691-534; e-mail: s.cousins@cranfield.ac.uk; Web site: www.cortexstructures. com. Circle 299

*Warm compaction plus heat treating strengthen P/M parts

Heat-treated properties of P/M steels after double pressing and sintering were compared with properties of warm-compacted powders after sinter hardening and heat treating in a paper presented at the 2003 SAE World Congress. Titled "Material Properties of Heat Treated Double Pressed/Sintered P/M Steels in Comparison to Warm Compacted/ Sinter Hardened Materials" (SAE Paper 2003-01-0338), the paper was prepared by Dave Milligan and Ulf Engstrom of North American Hoeganaes, USA; Jim Lingenfelter of Brockway Pressed Metals USA; and Senad Dizdar and Ingalill Nyberg, Hoeganaes AB, Sweden.

The purpose of the work was to determine if a gear made by the current process of double pressing/double sintering and heat treating, could be replaced by a warm-compacted and sinter-hardened gear, in order to reduce costs. By converting to warm-compaction and sinter-hardening, three processes could be eliminated. The two materials investigated were Hoeganaes Pre-mix Astaloy 85Mo, and Hoeganaes Densimix Astaloy 85Mo.

The green density levels for warm compaction are greater than or equal to the density levels achieved by double press/double sinter. For example, with the current process, green densities reach 7.33 g/ cm^sup 3^. With warm compaction, the green density is the same.

Parts made by the sinter hardening process approached but did not achieve the levels of physical properties achieved by the double- pressing/double sintering and heat treating method. Impact energy and elongation of the sinter hardened parts exceeded those levels, but the ultimate tensile strength and yield strength were lower.

When warm compaction was combined with secondary heat treatment, hardness levels comparable to those of the existing process were achieved. The physical properties also matched those of the double press/double sinter process. The yield strength for all the materials, except for the Astaloy 85Mo with copper, was greater than 1000 MPa (145 ksi). All other physical properties were comparable, including elongation and impact energy. In addition, fatigue strength is shown to increase when powders are warm compacted.

Actual warm compaction trials demonstrated that gears can be produced that match the density levels of the current process. By reaching these density levels, the physical properties, including hardness, can match the current process and eliminate pre-press and pre-sinter operations, offering significant cost savings.

For more information: David Milligan, Hoganas North America, 111 Hoganas Way, Hollsopple, PA 15935-6416; tel: 814/ 479-3634; e-mail: david.milligan@northamericanhoganas.com; www. northamericanhoganas.com. Circle 300

*Mechanical strength raised for welds in plastic parts

The mechanical performance of injection-molded, glass-fiber reinforced plastic parts was discussed in a paper presented at the SAE 2003 World Congress. Titled "Reinforcement Challenges and Solutions in Optimized Design of Injection Molded Plastic Parts" (SAE Paper 2003-01-1123), the paper was prepared by Christopher Roth and Val A. Kagan of Honeywell International, Morristown, N.J.

The purpose of the study was to show the effect of short glass- fiber orientation at pre-welded beads, ribs, and wall areas. Another goal was to evaluate the short-term mechanical performance of welded butt-joints that have various geometries and thickness, such as straight and T-type welds. Learning how to optimize the mechanical performance of these two weld types should help with materials selection, welding, processing, and design optimization.

The welding technologies for manufacturing thermoplastic components include frictional methods, such as linear vibration, orbital vibration, spin, and ultrasonic. Other methods include hot plate, both contact and noncontact; and laser technologies such as noncontact and contact/through-transmission.

The study showed that short glass-fiber reinforced nylon is the thermoplastic material of choice for a variety of injection-molded and linear-vibration-welded structural automotive components. For these highly stressed parts, frictional linear and orbital plastic welding methods are very efficient for joining thermoplastic parts in which high mechanical performance is a critical factor.

For T-type butt joints, the same high performance can be achieved when weld geometry is optimized and the glass fibers are oriented properly. Furthermore, the tensile strength of straight butt-joints was equal to or higher than the base polymer when both injection molding and welding processes were optimized. The paper contains various recommendations for the design of such parts for improved mechanical strength.

For more information: Dr. Val A. Kagan, Honeywell International, 101 Columbia Road, Morristown, NJ 07962-2332; tel: 973/455-2858; fax: 973/455-2936; e-mail: val.kagan@honeywell.com. Circle 301

*Arc-ion plated DLC cuts valve friction loss by 45%

Diamondlike carbon (DLC) coatings applied to valve lifters by arc- ion plating can reduce friction loss by almost 45%, according to a paper presented at the 2003 SAE World Congress by researchers from Nissan Motor Co. Ltd., Japan. Titled "Research on Diamond-Like Carbon Coatings for Low-Friction Valve Lifters" (SAE Paper 2003-01- 1101), the paper was prepared by Y. Yasuda, M. Kano, Y. Mabuchi, and S. Abou.

The study was done in response to reports that the valve train accounts for 20 to 25% of total friction losses at low speeds. DLC coatings were investigated because they have high hardness, low friction, and excellent wear resistance. They are deposited directly on component surfaces under vacuum, via several different chemical and physical procedures.

Results of testing with a motored valve train friction tester indicate that an arc-ion plated DLC coating on a valve lifter can reduce friction loss by almost 45%, compared with a phosphated steel valve lifter in a conventional valve train. In addition, other properties can be designed to match the intended application. These properties include surface hardness, film thickness, and surface roughness.

For more information: SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001; tel: 724/776-4841; fax: 724/776-5760.

*Common rail fuel injection developed for diesel engines

A common rail fuel injection system for diesel engines in which injection pressure is 1800 bar has reportedly been developed by Denso International America Inc., Southfield, Mich. The 1800-bar pressure is said to be the highest in the industry, and it provides better atomization of fuel with five fuel injections, compared with two for conventional systems. The result is more power, improved combustion, and cleaner and quieter operation. By injecting fuel at 1800 bar, the common railsystem raises diesel engine performance, while reducing emissions of particulate matter and nitrogen oxide.

The system is composed of a supply pump, a common rail with a high-pressure sensor, solenoid injectors, and a high-speed electronic control unit. The pump is made of aluminum and steel, and the housing is made of aluminum. The system is controlled by a 32- bit electronic control unit and associated software.

Results of testing with a two-liter, four-cylinder inline intercooler turbo-equipped engine showed that engine torque was increased by 35%, engine power was increased by 24%, and emissions of particulate matter and nitrogen oxide were significantly reduced.

For more information: Marlene Goldsmith, Denso International America Inc., 24777 Denso Drive, Southfield, MI 48086-5047; tel: 248/ 372-8222; fax: 248/213-2550; e-mail: marlene_goldsmith@denso- diam.com; Web site: www.globaldenso.com.

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*Stainless steel fuel rail cuts evaporative emissions

A Delphi Tech-2 fuel rail that helps reduce evaporative emissions and eliminates hexavalent chromium by replacing plated steel with stainless steel has received an Environmental Excellence in Transportation award from the Society of Automotive Engineers, reports Delphi Corp., Troy, Mich. The Tech-2 provides excellent damping with fewer components, and is more reliable. By eliminating the chrome plating process, the Tech-2 design also eliminates the need for 6000 pounds of hexavalent chromium and 4000 pounds of zinc.

For more information: Luce Rubio, Delphi Corp., Troy, MI 48098; tel: 248/813-2618; e-mail: luce.rubio@delphi.com. Circle 302

Applications of titanium to automotive parts have been considered for the last 20 years.

*Air-filtration module cuts parts by half, fasteners by 75%

A plastic air-filtration module for heavy-duty trucks that has 50% fewer parts and 75% fewer fasteners is reportedly in production by Mann + Hummel Automotive, Detroit, Mich. The design combines the air cleaner, cabin air filter, housings, and brackets into a single module. For the first time in a heavy-duty truck, the dean air elbow is welded to the filter housing, eliminating the clamp and steel ring required for conventional designs. In addition, the main filter element, the cabin filter element, and the optional safety filter element are all plastic and recyclable, for more information: Julie Morey, Mann + Hummel Automotive Inc., 6400 S. Sprinkle Road, Portage, MI 49002-8720; tel: 248/857-8515; e-mail: jmorey@mannhummelauto. com; Web site: www.mann-hummel.com. Circle 303

*2003 Porsche Cayenne features integrated front end module

The 2003 Porsche Cayenne includes an integrated front-end module made of StaMax P long glass fiber reinforced polypropylene thermoplastic from Owens Corning, Toledo, Ohio. The module consolidates many previous metal parts into a single carrier to which the bumper, horn, headlamps, radiator, fan, and condenser are attached. According to Owens Corning, the StaMax P composite provides a lighter, stronger, more economical solution than steel. Its uniform distribution of glass fibers within the polymer matrix enhances design flexibility. In addition, the composite properties and the molding process can be tailored to application requirements. For more information: Janet Galecki, Owens Corning, One Owens Corning Parkway, Toledo, OH 43659; tel: 419/248-7556; e-mail: janet.galecki@ owenscorning.com; Web site: www.owenscorning.com.

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*Engineering plastics raise raise race car ignition performance

Ignition components made of DuPont Rynite thermoplastic polyester resin withstand the high temperatures, severe vibration, and high voltages of advanced ignition products for race cars, reports DuPont Automotive, Troy, Mich, for example, the housing for a digital ignition tester is made of DuPont Zytel nylon, a conductive resin with built-in shielding properties. The ignition components are made by MSD Ignition, El Paso, Texas, primarily for race cars. Other components made of DuPont engineering plastics include housings for ignition coils and controls, distributor caps and rotors, connectors, and wire spacers. For more information: DuPont Automotive, 950 Stephenson Highway, Troy, MI 48007-7013; tel: 248/ 583-8000; fax: 248/583-4556; Web site: www.plastics.dupont.com. Circle 306

Semi-solid rheocasting creates semi-solid slurry quickly and efficiently from molten alloy.

Cortex structures are said to offer stiffness similar to automotive steels at less than 40% of the weight of steel.

*High-velocity impact fusion deposits zinc on steel sheet

A novel metal deposition process based on high-velocity impact fusion of solid zinc particles has been developed to extend the corrosion resistance of base steel and pre-galvanized sheet, according to a paper presented at the 2003 SAE World Congress. Titled "Selective Galvanizing Using Kinetic Spraying" (SAE paper 2003-01-1237), the paper was prepared by Robert C. McCune, Mark S. Ricketts, and Guilian Gao of the Ford Motor Co.; Richard A. Neiser and Joseph Puskar of Sandia National Laboratories; and Timothy J. Roemer of Ktech Corp.

Although large surfaces are protected from general corrosion through pretreatments and effective paint processes, certain details of fabrication are still subject to corrosion. These include welds, joints, crevices, occluded regions, and highly deformed surfaces. Metallic zinc in contact with steel acts as a barrier to the environment, and also exhibits sacrificial properties that !render the steel electrochemically immune to corrosion.

The cold-gas dynamic spray process, or kinetic spray process, was used to selectively galvanize precoated steel to enhance the corrosion resistance of structural features. The attributes of cold spray that are useful for this application include the ability to produce any level of zinc thickness; the fact that no plating baths or chemical processes are needed; and the ability to control the deposition to such an extent that masking is not required.

Results show that selective improvements in galvanic protection are possible because of the unique features of kinetic cold spray. The cold sprayed zinc currently has a corrosion rate that is comparable to that of electrogalvanized zinc or pure zinc foil in order of magnitude. However, its corrosion resistance could be improved, and is a subject for continuing study. Similarly, the most effective nozzle geometries and spray parameter details would need to be addressed for individual coating circumstances.

For more information: Robert C. McCune, Ford Motor Co., Dearborn, MI 48121-2053; e-mail: rmccune@ford.com.

*Three-valve architecture cuts size, weight in V-8 engine

A three-valve architecture that delivers the benefits of multiple valves in a smaller package has been developed at the Ford Motor Co., Dearborn, Mich. The three-valve architecture includes an all- aluminum head, a single camshaft, and magnesium cam covers. As a result of these materials, the part is dimensionally smaller and lighter than the previous two-valve head. It is also easier to manufacture, with simpler drilling angles and straight-machined surfaces. For more information: Ford Motor Co., Dearborn, Mich.; Web site: www.ford.com.

*Lost foam cast aluminum cylinder block enables built-in oil passages

This engine cylinder block is the third in the General Motors Vortex engine series to be designed specifically for lost foam casting. The aluminum alloy 356 block weighs 15 lb (6.8 kg) less than the comparable iron design, and was cast by the GM Powertrain Division, Defiance, Ohio. Lost foam technology allowed designers to cast in various features not possible with any other casting process.

Among these features are the main oil passages, which feed high- pressure oil to balance shafts, crankshaft bearings, and the cylinder head. Other cast-in features include the five oil feed holes from the main oil passage to each crank-shaft bearing surface; and the four oil feed holes from the main oil passage to both balance shaft bearing surfaces. Both balance shaft covers are also cast in, eliminating the need for two separate covers and gaskets. The part won a "Best in Class" award in the 2003 Casting Competition sponsored by the American foundry Society. For more information: GM Powertrain Division, General Motors Corp., 26427 State Route 281, Defiance, OH 43512; tel: 419/782-7010; Web site: www.gm.com/ automotive/gmpowertrain.

By injecting fuel at 1800 bar, the common rail system raises diesel engine performance.

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