DETROIT - Ford Motor Co. has decided to put ultra-lightweight metal matrix composite (MMC) driveshafts into the police cruiser versions of its standard-size Crown Victoria cars, which are ticketed for production and sale in volumes up to 65,000 annually--a record for MMC driveshafts in North American-built passenger cars, according to auto industry sources here.

MMCs have a high elastic modulus, which allows driveshafts made of the material to operate at higher speeds.

The aluminum MMC driveshafts will be installed in the Crown Victoria Police Interceptor models, as Ford calls them. The automaker will buy the shaft assemblies from its subsidiary, Visteon Automotive Systems, Dearborn, Mich.

Ford sources said that Visteon would put the driveshafts together using seamless extruded and drawn aluminum matrix composite tubes weighing 6 or 7 pounds apiece from the Extrusion/Tube division, Lafayette, Ind., of Alcoa Inc.

The facility will acquire the MMC billets as the raw material for the tubes from the Duralcan USA unit, Novi, Mich., of Alcan Aluminium Ltd. The billets are the products of the Duralcan plant in Dubuc, Quebec.

Most driveshafts use steel tubes, which are the principal components of the assemblies. Some, however, use conventional aluminum tubes, and some of those, in turn, employ graphite fiber wrappings for strength.

Most aluminum matrix composite tubes that have been put into use up to now were going into pickup trucks, but passenger car applications began showing up here and abroad a few years ago. General Motors Corp.'s Chevrolet Corvettes, which started using them in 1997, employ the units as standard equipment in volumes of 26,000 to 32,000 per year--more than any other known car application to date.

The Ford Police Interceptor applications, which are virtually certain to outnumber the Corvette installations, will start to be used this year, although Ford sources did not give an exact launch date.

The second-largest domestic automaker expects the Police Interceptor models, which differ from the regular Crown Victorias only in the rear-axle ratio and the specialized equipment they have on board, to account for 85 percent of all police pursuit vehicle sales in the United States and Canada for the foreseeable future.

Duralcan's Dubuc plant, which has a rated capacity of 30 million pounds per year, is regarded as the largest aluminum MMC ingot and billet manufacturing facility in the world.

The MMCs Duralcan makes for driveshafts and other wrought products contain up to 20 percent aluminum oxide particulates. Those composites also are used in the Corvette driveshafts (AMM, March 4, 1996).

Most of the new applications for MMCs that have been launched in the auto industry around the world started in the 1990s. Most of the materials are aluminum composites, which usually save weight even compared with conventional aluminum extrusions, castings or forgings. In addition to driveshafts, the applications for MMCs include brake rotors and drums, engine cylinder sleeves and sprockets.

Numerous other parts made in high volumes by or for the auto industry, including engine piston components and connecting rods, are regarded by auto engineers as candidates for aluminum MMCs as the automakers turn out lighter-weight vehicles with lower emissions characteristics and higher fuel economy in the future.

The new MMC parts are expected to be made in a variety of ways, including high-pressure die casting, gravity semi-permanent mold casting, extruding, rolling and forging.