The aluminum from the CASH 3 line will help Ford reduce the overall vehicle weight of the SuperDuty by up to 350 lbs (159 kg), improving fuel economy and towing capacity.

During the past five years, Novelis has expanded its ability to serve the North American automotive market by installing and commissioning the three automotive finishing lines in Oswego. This $400-million investment also includes the closed-loop recycling program. The Oswego plant is Novelis’ only fully integrated, wholly-owned facility in North America; production includes:

• Remelt/recycling
• Ingot casting
• Hot rolling
• Cold rolling
• Finishing

Novelis is the only automotive supplier producing high-strength, military-grade aluminum on all three major auto-producing continents—North America, Europe and Asia—in Oswego, NY; Kingston, Ontario; Sierre, Switzerland; Nachterstedt and Gottingen, Germany; and Changzhou, China. Novelis automotive aluminum is featured in more than 180 vehicle models currently in production by the world’s leading automakers.

Aluminum, automotive and CASH. Aluminum is a relatively recent discovery, as mainstream metals go. First isolated in 1825 and widely commercialized only after the invention of the Hall-Heroult production process in 1886, aluminum has become the second-most heavily used metal in the world after iron/steel.

A study recently released by the Aluminum Association found that the US aluminum industry contributes more than $75 billion to the national economy. When supplier and induced impacts are taken into consideration, the industry is responsible for nearly 713,000 jobs and $186 billion in economic impact—more than 1% of national GDP.

Although certain segments of the domestic aluminum industry have struggled in recent years—with major job losses particularly in the upstream segment of the business—these losses have been offset by gains in downstream sectors such flat-roll products, extruded products and foundries. Demand growth for the metal has continued including a near doubling of aluminum shipments to the transportation sector since 2009.

Aluminum’s use in autos and commercial vehicles is accelerating because it offers a cost-effective way to increase performance, boost fuel economy and reduce emissions while maintaining or improving safety and durability.

Because aluminum is lighter, it allows automakers to increase dent resistance—they can make body panels thicker while still lowering weight. A lower weight vehicle has better acceleration, better braking and better handling. In addition, lighter vehicles can haul and tow more because the engine isn’t carrying unneeded weight.

This metal is now a leading material for use in powertrain and wheel applications and continues to gain market share in hoods, trunks, doors and bumpers—and complete vehicle structures.

Aluminum is produced in two phases: refining the bauxite ore into aluminum oxide, and then smelting the aluminum oxide to release pure aluminum. Aluminum can be alloyed with magnesium, silicon, copper, zinc, and other elements to improve desired such as formability, strength, or corrosion resistance.

The chemical composition limits for alloys are reviewed and registered by The Aluminum Association, Inc.

• 5000-series alloys are used in structural and architectural products.

• 6000-series alloys are easily formed, machined and are used in auto structural and non-structural components.

• 7000-series alloys can be hardened to the degree that they are useful in aerospace.

Aluminum can be rolled, forged, cast or extruded. Rolling produces plate, sheet or foil. Plate is used in applications such as airplanes and building envelopes; sheet is used in products such as car bodies, cans and trailers; foil is used in food and beverage packaging as well as heat exchanges.

Aluminum sheet is is rectangular in cross-section and form, and of > 0.0079" (0.20 mm) thickness through 0.249" (6.3 mm) thickness. It may be produced in coiled or flat form, or in a variety of special shapes or fabrications. Novelis Oswego’s CASH lines work with coils.

Rolling—the initial production of sheet from an aluminum ingot—is done either hot (with heated, softened aluminum) or cold (at room temperature).

• Hot rolling has at least two significant metallurgical effects: it welds pores left by the casting of the ingot, creating a denser, stronger metal; and it breaks up and distributes hard constituents of iron and silicon which have formed at grain boundaries. This action transforms brittle cast alloy into ductile wrought alloy.

  Rolling temperature also influences appearance and structure of the final product. Lower hot-rolling temperatures yield relatively brighter product surfaces and elongated alloy grains, while higher hot-rolling temperatures can induce recrystallization in the metal. The rolling temperature is selected according to the product properties that are to be achieved.

  Because too high a temperature can weaken grain boundaries and cause boundary cracking, the rolling temperature is kept 10˚ to 50°C below the “solidus” or solidification temperature — of each alloy.

• Cold rolling makes the metal stronger and harder. When metal is deformed, as it is in flat rolling, regions of the crystal lattice structure slip past each other along glide planes. Cold rolling increases the number of dislocations which resist force and make the metal stronger and harder. This effect is deliberately induced as “work hardening” to strengthen aluminum alloy products.

  Work hardening has a natural limit for each alloy because it is straining the alloy toward its strength limit. The number of dislocations which a crystal lattice can develop is limited and, therefore, so is its maximum strength. As work hardening increases, the metal can withstand increasing force without breaking; but it retains less reserve against additional force.

  The heat of annealing relieves the distorted, dislocated lattice structure and allows it to reform in relatively undislocated planes again, restoring ductility at the cost of the acquired strength.

Full annealing heats the alloy hot enough and long enough to soften the product completely—i.e., to achieve full recrystallization. Partial annealing—as used at Oswego—by contrast, applies patterns of temperature and time to develop properties in between fully soft and fully work hardened. Process control parameters are determined by the alloy being finished and customer requirements.

In sheet annealing, uncoiled sheet is passed through a furnace so that its entire surface contacts and is heated by the hot furnace atmosphere. This heats the sheet rapidly, permitting the development of a finer alloy grain structure. Oswego anneals its uncoiled sheet with as continuous sheet passed through the furnace from coil to coil.

Top. Uncoiled sheet heading for the furnace (made by Ebner)—the structure at the back of the photo. Once in the furnace, the sheet rides on a bed of air to prevent touching rollers (called a “floater furnace”). (The large vertical ducts arrayed down the right side of the photo source the air for the blowers.) Once out of the furnace, it loops down for cooling and an acid bath treatment. Bottom. Sheet “floating” on air through the furnace. Click to enlarge.

Novelis’ new CASH 3 line essentially uses the same technology as it two sibling lines, with the inevitable tweaks and process control enhancements enabled by experience with the first two.

The line operates at two levels. Sheet is uncoiled at one end, raised to a second level where it enters the furnace (492 - 560 ˚C, depending upon alloy). It then is cooled, and loops down to the lower level for chemical treatment and rewinding. Processing of a single coil takes between 30-60 minutes, depending upon the alloy.

CASH is a continuous process; coils are joined to enable a continuous ribbon of aluminum sheet to run through the finishing process. This mechanism above enables the line to keep running at the top level while the coils are stitched at the bottom; the orange tensioner moves up or down depending upon whether or not it needs to feed the “buffer” sheet wound around the rollers while the end of the coil sheet is stationary for joining to the next. Click to enlarge.

Closed-loop recycling. Working together with Penske as the logistics provider and manager and Ford as the customer, Novelis has implemented a closed-loop recycling process to produce aluminum bound for Ford trucks.

The closed loop program is relatively simple to describe:

• Specially designed Penske tractor-trailers collect aluminum stamping scrap from Ford Dearborn. The scrap is segregated by alloy at the collection point, and blown into the custom trailers designed by Penske. The alloy type is identified with the trailer.

• The trucks drive the scrap to Oswego, where it is unloaded and remelted for ingots for processing. Because of the careful segregation and management of the different alloy types, little extra processing is required on the Novelis end.

• The now-empty trailers, which are multi-function by design, are now loaded with new aluminum coil, and drive back to Dearborn. The loop runs 24 x 7 x 365.

Realizing the program took several years of work and design, however, especially on the design of the tractor-trailer and the overall collection and transportation process.

Penske’s tractor-trailer for the closed loop program. The trailer is multi-functional, with a motorized, retractable roof. At Ford Dearborn, aluminum scrap is blown into the trailer, avoiding the energy and time costs of baling and unbaling scrap. The retractable roof is rugged and watertight; moisture contamination of the scrap is important to avoid, and the route from Dearborn, Michigan to Oswego, New York, sees more than its share of rain and snow. At Novelis, the trailer is raised to tip the scrap for recycling. The roof is then retracted, allowing cranes to load the trailer with coils for transport back to Ford. Note the triple-axle on the back of the tractor to accomodate the multiple functions. Penske currently has 144 trailers and 50 tractors dedicated to the program. Click to enlarge.

Resources

• Rolling Aluminum: from the Mine through the Mill