ALUMINIUM 

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Aluminum And Vehicles

Transport is the biggest single user of aluminium, accounting for nearly one third of all the metal used in Europe.

One good reason for this is that moving weight costs energy In the average car today, for example, there is about 50 kg of aluminium, in components from engine cylinder blocks to radiators. It has been calculated that the resulting 100 kg weight reduction compared with iron, steel and copper saves some 1,500 litres of fuel over the life of the vehicle.

aluminum vehicle

In urban transport systems like buses and trains, which are constantly accelerating and decelerating, weight saving counts for even more. Aluminium is today the natural choice for public transport coachwork. Commercial vehicles and earth-moving equipment with aluminium bodies can carry greater payloads. Aluminium alloy wheels are now being widely adopted for road trucks, as the pay-offfrom dead-weight saving becomes more widely appreciated.

A further contribution to road transport is made by aluminium as the universal material for road signs, and by its increasing use in motorway parapets and bridges.

At sea, aluminium alloy super structure on ships lowers the centre of gravity, improves stability and allows for more accommodation as well as saving on maintenance. In offshore structures, every tonne saved above water saves much more weight and cost in support structure, and the ability to pre- assemble much larger units saves off shore fabrication. Masts on small craft are almost invariably of extruded aluminium these days. About 70 per cent of the weight of a modern aircraft is accounted for by aluminium alloys, and it is difficult even to imâgine how modem air transport could have developed without the light metal.

It is not only aluminium's lightness which makes commercial llying possible; unlike most steels, aluminium alloys do not suffer from embrittlement at the very low temperatures met with in the strato- sphere. On the other hand even Concorde, which by virtue of its great speed is subjected to consider able friction heating, is a virtually all-alloy aircraft, the wing leading edges being cooled by intemal cir culation of fuel. Perhaps the most significant advance in this field since the development of Duralumin (Al-Cu alloys) is a range of aluminium-lithium alloys which are ten per cent lighter still, as well as stiffer They promise airframe weight reductions of 15 per cent or more in future.

Aluminum Conductors

aluminum conductor

In view of aluminium's excellent electrical conductivity it is not surprising that about one-tenth of Europe's consumption is in the electrical and electronics fields. Perhaps the most familiar application is the overhead supply grid, almost universally of stranded aluminium. Because of the long life of these systems, the annual usage may not be immense, but it is likely that the amount of metal hanging up there is at any time greater than that in any other single application. Not only would the cost of the equivalent in copper be prohibitive, but the greater weight would mean bigger, heavier and more obtrusive pylons to carry it.

Aluminium is used in underground cables and busbar systems, and for motor windings. The typehead of many printers moves as part of a linear motor with an aluminium stator bar, and such devices on a larger scale are coming into use as the motive power for rapid-transit systems, sometimes combined with magnetic levitation. In electronics, aluminium is found in chassis, chips, transistor heat sinks, data storage disks and strong, impact-resistant cases for electronic equipment of all kinds, from mobile radios to microcomputers.

Engineering With Aluminum:

High strength: weight ratio, resistance to corrosion and ease of fabrication combine to give aluminium and its alloys unique advantages in mechanical applicacations. Light weight means that larger single components can be easily handled, while the ease of manufacture to fine limits makes for precision assembly of large structures from standard units.

Complex sections, often snugly interlocking, can be extruded in a way quite impossible with almost any other metal, to form effcient structures - helicopter landing pads are a good example - in which the metal is distributed exactly where it is required.

As the speed of mechanical operations increases, especially in motive power units and in autömated and robot operations, low mass and therefore inertia become more important if precision is to be maintained and energy saved.

Gearboxes, engine blocks and cylinder heads can be cast, or die cast, in the most complex shapes, with fewer components and assembly operations, and fewer joints to leak or affect alignment. The adoption of aluminium as the basis of crankshaft bearings has virtually eliminated failure in service.
 
 

aluminum wheel

aluminum castings

 

Aluminum And Energy Saving

From 1950 to 1986 technical innovation has significantly reduced energy consumption required for the production of aluminium by some 30%. In the Western World, 61% of the electricity required comes from inexhaustible and ecologically friendly hydro power Aluminium is an "Energy Bank'; unique in storing the energy used for its production as its products can be recycled indefinitely.

Countries producing aluminium have the unique opportunity to export one of their natural resources energy in form of aluminium ingots. Today, some 35% of the total aluminium consumption in Europe is reclaimed from scrap with an energy saving of 95% compared to primary production. To evaluate the energy balances, the total energy requirement within a given product application system and the total energy saving during a product's lifetime must be considered rather than just the product or comparing a kg of one material with another.

To take an actual example, using aluminium instead of steel in a dump truck involves an energy penalty of 70,000 kWh. But the energy saved due to weight reduction over a five-year life is no less than 250,000 kWh - nearly four times the initial extra cost: and of course the dump truck inevitably uses irreplacable fossil fuel, whereas the smelter's power mayjust as well come from hydro-electric, tidal, nuclear or other sources.

Similar but even more dramatic, comparisons can be drawn from the use of light aluminium alloys in rail and other forms of transport. And even assuming that aircraft could get off the ground without aluminium, the fuel penalty there would be quite unacceptable.

Aluminum Recycling

Aluminium's high scrap value encourages recycling, with the result that it is not a significant contributor to waste disposal problems because it can be collected before waste. Scrap from manufacturing processes is invariably reprocessed. One third of all aluminium comes from scrap, and as much as 70% of the metal used in electrical engineering, building and transport is re-used, often again and again. An aluminium can may become another can within a few weeks. A window frame may enjoy its reincarnation only after fifty years.

ACRE (European Can Recycling Association) reports that 37% of UBC (used beverage can) is recycled every year. It is expected the recycling rate will increase to 50% in near future. 

On the other hand, recycling rate of UBCs in the US reached 66.5% in 1997. (Aluminum can production increased by 6.5% totaling 100.5 billion units.)

aluminium recycling

In Scandanavian Countries recycle 90 % of cans. The avarage recyclig rate of all aluminum cans in Western Europe reached 57% in 2006. (Source: BCME)

Aluminum And Enviroment

All industrial processes impinge on the environment in one way or another. Aluminium's record is a good one. None of the aluminium manufacturing processes involves significant hazards to health or to the environment.

For many years the aluminium industry has dealt with environmental problems and acted correspondingly. This has lead to great successes as for example the halving of the fluor emissions or a reduction of the dust by 75%. Electrolytic cells have been encapsulated to collect and clean emissions. Very often the achieved rates for environmental protection range below the legislative limits. The continually measured emission rates of the aluminium smelters exclude a health hazard.

Unlike some raw materials, there is no question of enjoying the benefits of aluminium today at the expense of future generations.

 

Sources Of Aluminum

As the third most abundant element in the Earth's crust, there is potentially enough aluminium to last as long as human life itself.

Known reserves of the current predominant source, bauxite, would alone keep us going at the present rate of consumption for three thousand years, and new deposits are being discovered at about twice the current rate of consumption. And research into altemative sources, such as kaolin-based materials, proceeds apace.

Bauxite is mined by open-cast working, and it is routine to prepare plans for restoration of the landscape before digging begins, so that the land is recovered for reafforestation or whatever form of restoration is environmentally appropriate.

It is economically sensible to reduce the bauxite to alumina before shipping it to the smelters, creating local industry and employment in the predominantly developing countries where it is found.

Aluminum And Future

The accelerating advance of industrial technology has been matched by the growth in the use of aluminium, and the role of the aluminium industry will expand just as the advantages of stronger, lighter, more efficient, economical, attractive and long-lasting products of all kinds become more apparent.

 

In every form of transport, including space travel, in more attractive buildings and bridges, in energy transmission, in domestic products and packaging, in general engineering, aluminium will become more and more indispensible.

The aluminium industry in the world is devoting huge resources to the development of improvements in raw material recovery, production and manufacturing techniques, to the creation of new alloys, to product design and quality control, as well as devising advantageous new ways of using the metal.
 
 

Aluminum And Quality

Primary Aluminum's quality is closely related to the quality of the bauxite ore and the operational conditions of the reduction cells of the smelter.

Extruded and rolled products that will be used for architectural and decorative purposes should prefarably made of the grade Al99.7 for the best anodizing properties to ensure Fe (iron) content not to exceed 0.25%. This is also important for the "filiform corrosion" phenomenon that is encountered in painted aluminum in certain conditions.

ESTAL (European Aluminum Surface Treatment Association) has issued two separate specifications and quality labels, QUALANOD and QUALICOAT for the anodic oxidation coating and painted aluminum respectively, for architectural use.

TSE logo

QUALANOD logo

QUALICOAT logo

 

In Turkiye, TSE (Turkish Standarts Institute) and AYID (Aluminum Surface Treaters' Association in Turkiye) are cooperating in this field to inspect anodizing and powder coating plants and grant QUALANOD and QUALICOAT labels as well as TSE's own quality label. 

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Timur Ulucak
Metallurgical Engineer(M.Sc)
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