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Market drives automotive castings to aluminum.

Satchel Paige once counselled, "Don't look back cause someone might be gaining on you.' Coaches at a famous baseball school down in Missouri used to tell the boys that loud whistling was the best way to chase off 'the ghosts' who rattled their chains in the middle of the night around the dark bunkhouses.

A decade ago, American automobile manufacturers didn't look back nor did they hear the rattling chains of foreign car producers. The result has been that they have been nearly overwhelmed by foreign competitors who play by different and often superior design, production and quality rules.

And vehicle manufacturers were not the only ones wearing blinders. Producers of consumer, commercial and industrial goods also have lost some of their manufacturing standing in the world's trade marathon. Unfortunately, short-term gains have too often taken precedence over long-term investment and a recognition of the world's new set of competitive circumstances.

A case in point is the belated switch to aluminum in domestic automobiles and light trucks. While overseas carmakers have been forming competitive strategies on prototype casting lines, U.S. car companies have lobbied for protectionism and the right to produce larger vehicles. in the last decade, European and Asian vehicle makers have been progressively substituting aluminum parts forcast iron to improve gas mileage.

Many American producers have clung to ferrous materials for engine blocks, cylinder heads, wheels and chassis parts and fought for lower legislated mileage limits rather than meet head-on the move toward lighter vehicles.

All this is beginning to change, however, as U.S. carmakers opt for other materials, particularly aluminum, to bring down vehicle weight and compete more successfully against overseas carmakers. Only as the domestic automakers commit to more aluminum in their vehicles are U.S. foundries gearing up to supply the demand. The potential domestic market for aluminum primary and aftermarket automotive castings is huge. Capturing this demand is critical for the U.S. foundry industry as it struggles to shore up its dwindling market share.

World Market

Aluminum foundry production varies significantly between the major industrialized countries, as noted in Figs. 1 and 2, with the world's largest user of aluminum castings being the automotive industry.

Japan, with the highest compounded growth, has car companies that use all aluminum heads and a significant portion of aluminum blocks (Honda 100%, Toyota and Nissan moving toward 100% by the year 2000). An intense drive is underway to further reduce the average weight of Japanese cars, speeding the conversion to aluminum castings. New aluminum foundries of all types will have to be built, but as of now location and staffing will be up to the Japanese, not the Americans.

The U.S., with the lowest compounded growth, still relies heavily on cast iron, especially for blocks and heads. Historically, the U.S. car companies have imported a significant portion of their castings. Whole engines, some with aluminum heads and blocks, are being imported from Japan and Europe.

The cost of aluminum versus the cost of iron is often identified as one of the major reasons for remaining with iron. With North American-produced cars already at a cost disadvantage compared to many foreign built cars, the reasoning is that U.S. car manufacturers cannot afford the switch to aluminum.

However, factors other than material costs have emerged to make aluminum castings an economical, even a mandated, alternative. CAFE (Corporate Average Fleet Efficiency) requirements, environmental considerations, Asian competition (high performance, multivalve engines, etc.) and near-net-shape casting capability have made aluminum more attractive. Demands for increased fuel economy and reduced emissions force automakers to look for weight reductions. Unfortunately, this effort runs counter to the automotive push for greater safety, which means options such as air bags and anti-lock brakes that add to average vehicle weight, adding urgency to weight reduction efforts.

Probably the greatest factor that would accelerate, or hinder, wider usage of aluminum within the Big 3 is CAFE. Whomever does the best legislative jawboning, lobbying and P.R. in Washington will decide the intermediate fate of aluminum in American-produced cars.

The real question is when, not if cars will go through the next weight reduction cycle. Car downsizing may prove to be a quicker, more productive strategy than material substitution. Current cheap fuel prices and consumer preferences for larger, safer cars mean that there is significant room for fleet downsizing should global developments, likely oil related, precipitate another CAFE mpg rise.

Engine Blocks

The engine block is the heaviest single cast part in an automobile. In terms of ideal weight distribution, it is located in the worst possible place for overweight front wheel drive cars. The secondary weight reductions possible make block conversion to aluminum even more attractive. This multiplier effect" could take an additional kilogram out of the vehicle for every kilogram the block weight is reduced by capitalizing on redesign opportunities in engine supports, wheels, tires, suspension components and brackets.

Greater vehicle fuel efficiency can also stem from more efficient engines that deliver higher horsepower/liter of displacement. These high performance engines also generate significantly more heat that needs to be transferred out of the cylinder. Aluminum offers superior heat transfer characteristics compared to cast iron, making it a more desirable engine block material. Unfortunately, current state-of-the-art for mass produced aluminum engines still incorporates a cast iron sleeve which retains heat and creates casting difficulties in some cases,

Over five million aluminum blocks are produced per year worldwide. Figure 3, a breakdown of aluminum block production by process, shows that the majority are cast using high pressure diecasting, mostly by Japanese and French foundries.

High pressure diecasting (HPDC) offers the advantages of close tolerances, high production and minimal machining. These advantages are counterbalanced by the constraints inherent in designing around the limited use of cores, high initial tooling and equipment costs and the inability to heat treat the casting. High pressure blocks are limited to open deck designs which beg questions of gasketing reliability, increased noise and lower stiffness, when compared to a closed deck.

Roughly 20% of the world's aluminum blocks are cast using permanent mold processes-gravity, low pressure or medium pressure each able to produce a closed deck block. Each also has individual drawbacks. Cycle time can be longer than HPDC (low pressure, gravity), scrap can be high medium pressure) and equipment/tooling conversions can even be greater than high pressure (medium pressure).

Sand processes also are used-no-bake, low pressure (sometimes called precision sand) and EPC. Nobake gravity systems are used only for limited production runs of highly specialized engine blocks. Low pressure sand methods, under a variety of names, have only recently been used in a new U.K. foundry and are scheduled for a Canadian foundry under construction. The only EPC aluminum block foundry is in the U.S. and has been in operation one year. While sand processes have not played a major role in aluminum block casting, they could take an increasing share of this market if the three new foundries are successful.

Aluminum block production in this country is still in its infancy but it's growing up fast, from a quarter of a million units in the late 1980S to over one million projected for 1992, a demand requiring the full utilization of North American capacity. if this demand continues to rise throughout the decade, as most estimates predict, by the year 2001 there could easily be an annual demand for four million aluminum engine blocks. This translates to 1150 good blocks per hour, two shifts, five days a week. Projected North American capacity for 1992 is 300 good blocks per hour.

Though a great opportunity for foundries, it is uncertain whether the Big 3 or independent aluminum foundries will make the investment necessary to meet this demand.

Cylinder Heads

Few foundries have all the necessary capabilities to produce aluminum blocks or cylinder heads. However, a review of the current U.S. cylinder head market can provide some interesting insights for all aluminum foundries, regardless of their product lines.

When analyzing the aluminum head market, does it mean engine heads for cars produced by the Big 3? Does it include the engines built by the transplants and/or imports? By narrowly defining a market, one might derive an artificial market segment leading to the faulty penetration conclusions.

For example, in 1990, there were approximately 7.5 million aluminum heads in passenger cars purchased in the U.S. but only slightly more than half of them were made in North America. The rest were from foreign built engines sold to the Big 3, foreign built engines used in transplant assembly facilities or entering the country on imported cars. Of the 3.55 million heads produced for Big 3 North American made engines, scarcely half were made in the U.S. Therefore, of the 7.5 million aluminum heads domestically 'consumed" in 1990, only a fraction were U.S.-built.

Even if all heads for North American built engines were made in the U.S., American foundries would still only represent just over 50% of the total market. Unfortunately, this troubling trend may only worsen if Big 3 car companies can't afford development of the next decade's engines and increase their purchases of foreign built powertrains, further eroding the market for North American produced aluminum heads and blocks.

While the number of aluminum heads consumed in North America will increase, the business going to domestic foundries may actually decrease. Clearly, we are immersed in a world marketplace where real or threatened trade barriers will, at best, only slightly slow these product flows. The solution, therefore, lies in producing heads wherever the engine plants are, even if it's halfway around the world, a strategy that holds true for all cast parts.

Selling only through existing channels to existing customers is a prescription for failure in today's marketplace. To survive, much less grow, American foundries must market and sell castings to the transplants and begin selling overseas for use in vehicles that may be destined for

Other Automotive Components

The production of aluminum blocks and heads is important because of the impact on the industry of the huge tonnage involved. However, other recent developments, notably in braking parts (rotors, drums and calipers) are becoming viable. Previously the domain of ferrous casting, aluminum-based metal matrix composites (MMCS) that offer improved strength and wear characteristics at a fraction of the weight of iron are being considered for these applications.

MMCS combine a metal matrix with a reinforcing material (in this case an aluminum alloy mixed with nonmetallic reinforcements such as silicon carbide particulate). The resulting composite has tensile yield strength, tensile ultimate strength and elastic modulus values higher than those of unreinforced aluminum. Added physical property enhancements include increased thermal conductivity and wear resistance.

Figure 4 compares the improvement in high temperature mechanical properties of a composite material compared to the unreinforced matrix. These and other improvements were substantial enough to warrant the development of MMCS for use in automotive braking components.

It is reported that brake rotors made from MMCS are about a third as heavy as cast iron, conduct heat away from brake pads better, wear longer and are quieter.

An MMC disadvantage is cost. The finished cost of an MMC rotor (including machining) is double that of a conventional iron rotor. Polycrystalline diamond tooling is required because of the hardness and abrasiveness of the silicon carbide reinforcing particles, and this also adds to cost. An advantage, however, is in the weight savings of MMCS over iron-upwards of 37 pounds of unsprung weight in the "comers" of the car, assuming rotors on all four wheels.

Several domestic and foreign car manufacturers are testing MMC brake rotors and Ford and Toyota have indicated their commitment to put MMC rotors in their cars. Also, to lighten up light" trucks and vans, designers are looking at MMC brake drums. Braking systems of lightweight electric powered cars offer additional opportunities.

Brake caliper development also is in progress and several companies have components in various stages of testing and evaluation. Calipers, however, will be a much more difficult application for MMCS because of the critical nature of the component. Unreinforced aluminum calipers are in use today for certain demanding, high performance applications, but the lower modulus of aluminum (essentially one-third that of iron) requires an inversely proportional cross-sectional area in the bridge to achieve equal part stiffness. The improved modulus of MMC'S allows a reduced cross-sectional bridge area permitting the MMC part to fit into less space and increasing the number of vehicles into which MMC calipers might be designed.

The metallurgical, mechanical and quality requirements of automotive braking components demand a casting process with excellent repeatability. To date, MMC braking parts have been made successfully in green sand, nobake, HPDC and EPC.

Brake rotors, drums and calipers cost more than iron but their weight savings potential and performance characteristics make them competitive. With a yearly world market of 65 million rotors, 90 million drums and 65 million calipers, even a modest conversion to MMC would mean big aluminum opportunities.

Suspension parts (suspension arms and steering knuckles) in aluminum also are being developed around the world, using materials and processes traditionally not seen in typical automotive productions-200 series aluminum, indirect squeeze casting, etc. More common in performance cars (Porsche, Honda NSX), soon aluminum suspension parts will be showing up in Fords, Buicks and Pontiacs as weight reduction dictates.

While aluminum suspension parts have a longer and broader history than their aluminum MMC relatives, their widespread introduction is by no means assured. In fact, thin wall ferrous materials cast via pressure/vacuum systems have in some cases retaken the ground lost to aluminum.

This has always been the way of production-one material vying for applications traditionally held by another and new processes seeking their niche among the more widely accepted techniques. Despite various challenges, substantial growth in aluminum automotive castings will occur through the 1990S and into 2001.
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Title Annotation:replacement of ferrous materials with aluminum and composite materials
Author:Bex, Tom
Publication:Modern Casting
Date:Feb 1, 1992
Previous Article:Environmental: 'what's hot and what's not.' (environmental and occupational safety regulations covering foundries)
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