Before the 1980s, the restriction ofpatent limited the use of dry sand lost foam casting without binder in production to a great extent, and the development of lost foam was quite slow. After the 1980s, the patent technology of lost foam casting failed, the quality of expandable polystyrene raw material beads and model combination binder has been greatly improved, and high-quality coatings have also been successfully developed. These have promoted the rapid development of lost foam casting technology and quickly been widely used all over the world.
In 1980, Ford Motors began to use lost foam casting process to produce aluminum alloy engine intake manifold castings in Essex, which significantly improved the quality of castings. 4 years later, Ford Motors spent $11 million to install the automatic lost foam casting production line in the same workshop. The annual output of the intake manifold reached 3 million and the reject rate was only 5%. Most of the waste products were caused by foam pattern damage.
In 1982, G. motors built a fully automatic lost foam casting production line for aluminum alloy cylinder heads, intake and exhaust manifolds and other castings. Five years later, its subsidiary Saturn introduced a lost foam casting production line from fata company in Italy and Vulcan company in the United States to produce engine block and rear axle castings, with a production efficiency of 80 cases per hour.
In 1984, an automatic lost foam casting production line for producing gray iron castings was built in Robinson casting company and put into operation. The daily output of castings can reach 50t.
In 1990, GM spent a lot of money to introduce three lost foam casting production lines from fata company in Italy, which are respectively used to produce aluminum alloy four cylinder block, aluminum alloy cylinder head, nodular iron crankshaft and differential housing.
In 2001, SmCo affiliated to General Motors built a lost foam production line for the production of six cylinder cylinder cylinder and cylinder head of sports cars. The daily output of both products reached more than 2000 pieces, and the total scrap rate was less than 12%. SmCo’s lost foam casting production line is the most advanced and largest in the world. Its completion marks the maturity of lost foam casting Technology in the United States.
Up to now, the lost foam casting technology in the United States is still the most advanced in the world, and the total output of lost foam casting has always been in the forefront of the world. According to statistics, the total output in 1997 increased by 27% on the basis of 1994, reaching 140000 tons, of which aluminum alloy castings accounted for about 60%; By 2001, the total output of lost foam casting castings was about 210000 tons.
In 1997, the American Foundry Association conducted a survey on the lost foam casting industry. It is considered that the lost foam casting industry in the United States has experienced three stages: the first stage is from the late 1950s to 1990, which is a difficult and long “period of technological innovation”; From 1990 to 2004, it was a “growing period”. During this period, lost foam casting has developed rapidly in application scope, casting output and process level; It is expected that in 2005, 2007 and 2013, aluminum castings, iron castings and steel castings in North America will enter the “mature period” respectively, accounting for 29%, 15% and 9% of the total output of metal castings respectively.