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Metal Casting Technologies : September 2008
TECHNICAL FEATURE Figure 3. Casting (Left) and foam patterns (Right) of an aluminum intake manifolds produced by FAW, (Courtesy of Zhenjia Xia, FAW) be seen in Figure 3. The thinnest wall measures only 4 ± 0.5 mm. The material is ASTM6876 (319) aluminum alloy. About 400,000 of intake manifolds had been manufactured before this product went to the end of its life cycle as auto engine design was changed. FAW is the only major auto maker in China that has stepped into making aluminum parts by lost foam process. Lost foam technology has also been widely used for art castings in China, following its origin when it was first developed in the US.5 Aluminum, bronze and iron are popular for usage in this market. Although the absolute market value is limited, the technical challenge is even higher than mass production in industry. A competition on lost foam art castings was held several years ago by the China Lost Foam Association. The big bell in Shenzhen stock exchange market, one of the only two stock exchange markets in China, was made from the lost foam process. Prototyping is another big application of lost foam technology in China, although this application is not normally presented to the lost foam industry. In fact, prototyping has been carried out to make tooling for foam patterns for lost foam process. As mentioned above, the full mold process has a big market share in China. Forging molds or dies is the largest application for full mold castings.6 These castings normally are big in size and are high value added. As the domestic automobile market grows in China, demand for these castings increases at a double-digit percentage rate. China is the third largest automakers in the world, following the United States and Japan. China manufactured 5.85 million automobiles in 2005 and 7.2 million in 2006. The demand for castings of forging molds or dies was 110,000 ton in 2005, only 50% to 60% were produced in China. It is predicted that automobile production in China will be 10 million units in 2010. The corresponding demand for castings of forging molds or dies will reach up to 200,000 ton in 2010. 68 www.metals.rala.com.au Investor’s opinion Lost foam technology has been promoted by the Chinese government as an alternative “green” casting process in hope of reducing pollution that can come to the environment from the casting process. The most attractive feature of the lost foam process for investors is its relatively lower investment compared to conventional sand casting and other processes. The complicated equipment for core and mold making for sand casting are replaced by foam molding and gluing machines which are cheaper. In addition, sand reclamation is easier for the lost foam process than that for sand casting. Foam molding and gluing are labor intensive. Foam molding and gluing machines are manually operated in many lost foam foundries in China. This is an additional advantage of the lost foam process for China. Although the economic advantage of the lost foam process is achieved only if the quantity of castings poured reaches an adequate amount, quite a lot of investors jumped into lost foam casting industry just because of the lower initial investment for equipment. A lot of these investors were fortunate and successful, as can be seen in figure 1 by the rapid increase in casting tonnage by the lost foam process in recent years. This has been beneficial to the advancement of this technology in China since its early development stage. As the whole industry has been gaining confidence with this technology, some investors are expanding their lost foam facilities and several more investors are planning to apply this process for mass production. But some investors were less fortunate, they failed completely when they found out that they could hardly produce qualified castings because they had not acquired the most advanced knowledge on the technology itself and they are even more in need of experience on process control.