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Metal Casting Technologies : June 2007
TECHNICAL FEATURE 24 www.metals.rala.com.au These figures indicate large numbers of vehicles, and an overall figure distinctly getting larger by the hour. According to the China Council for International Co-operation on Environment and Development (CCICED), there are currently 800 million passenger vehicles on the world's roads, with many more expected to be added by demand from China (and India), which presently has a very low car ownership rate when compared to industrialised countries. By 2030, it is expected that this figure will increase to 2 billion cars, with the greater part of the increase expected to come from both South Asia and Far East Asia. Correspondingly, the Energy Information Agency (EIA) states that much of the increase in world demand for oil comes from the transportation sector, which accounts for 50% of projected demand to 2030. In the US, a full two-thirds is used for transportation (primarily passenger cars), while for the rest of the world it is used for heating and power generation; the US is currently responsible for 37% of global GHG transportation sector emissions. FUEL CONSUMPTION STANDARDS Fuel consumption standards are but one of the weapons in an armamentarium to achieve reduction and stablisation of GHG emissions. For example, China's standards for lightweight vehicles, modelled on the EURO standard, was introduced in 2005 - it will introduce Euro III in July 2007, and Euro IV in 2008. (See Table 2). Some Chinese commentators regard the country's fuel consumption standard as 'aggressive'. With around 100 automotive manufacturers now comprising its industry, with a reliance on oil importation where once it was self-sufficient, thereby placing it in international competition with countries such as the US and India, underlined by its attempts to repair the environmental damage inflicted on itself with three-decade long development-at-all-costs economic policies, it is correctly seen by some quarters as a measure to force consolidation of the industry. Understandably. Al AND Mg COMPONENTS WELL ESTABLISHED Attempting to realise reductions in GHG emissions vis-à-vis increasingly stringent fuel consumption standards, international car and automotive components manufacturers have been exploring another weapon -- substitution of steel with lightweight metals such as aluminium and magnesium. Use of aluminium has been recorded as far back as the 1950s, with piston manufacture; according to the Aluminum Association (US), wider industry use has been pursed more vigorously since the late 1970s to mid-1980s. International use of aluminium components within automotive manufacturing has since then become well-established. (See Table 3). As substitute, aluminium possesses numerous favourable characteristics: it is highly recyclable, possesses small density, strength, hardness, elasticity (absorbing more crash energy than steel) and has good anti-corrosive qualities. Aluminium use also translates into compelling environmental effects. Substitution of steel with 10% aluminium decreases energy consumption by 8%, saving up to 0.7 litres of petrol. A 50% decrease in car weight results in a subsequent 13% decrease in CO2 emissions, while a 25% reduction in weight results in reduction of CO2 by 0.15 billion tonnes (with similar rates for NO2 and SO2 ) with a corresponding saving of 850,000 barrels of oil. Magnesium use within the automotive industry also has a colourful history. The German manufacturer, VW, had used it from 1939 to 2003 within its iconic Beetle, in 25kg casting transmission housings for its air-cooled engine. And the present-day automotive manufacturing industry continues to be the largest user, in drive train, engine, trimmings and steering wheel applications. Magnesium's characteristics are well-known. It has two-thirds the density of aluminium and is lighter; however, it still suffers corrosion resistance and strength second to that of aluminium. ENGINE BLOCK PRODUCTION Until now, examination of the environmental effects of lightweight materials such as aluminium and magnesium seem to have been considered in isolation from the entire production process. That's why the work of Tharumarajah and Koltun is particularly instructive. Table 3: International automobile aluminium content (kgs) Year Country/Region US Europe Japan China 2006 144.5 117.3 113.7 2010 330 Source: Aluminum Association (US) Liu 2005 Table 2: Present and proposed passenger vehicle fuel consumption standards Country/Region Litres/100KMS US 9.4 China 6.8 (2005) Australia 6.8 EU 5.3 (2008) Japan 4.9 (2010) Source: Lamb 2006