More than five thousand years ago in ancient time, metal processing began from casting and melting.In 1250,history of human development from the Stone Age,Bronze Age and later is Iron Age.Now goes into the plastic,aluminum era.The history of casting begins from copper alloy,iron,steel,to aluminum.The initial casting metal may be copper and gold,because oxide copper can be simply restored by fire,and gold has a natural presence of gold.That two kinds of metals can be melted by fire,melting crucibles and molds containers are available everywhere found by clay and sand.Iron castings temperature is higher than copper alloy,therefore iron casting started until 1812,only lasted less than 200 years.These may be mastered with the melting temperature.Whereas the application of aluminum so late,not due to the melting temperature,but without melting electrolysis from bauxite ore is not able to get aluminum.Aluminum melting point is lower than iron.It is light in quality,but heat resistance is its biggest drawback,which is unable to meet the high temperature of the occasion.But recently significant progress in the main components of the engine with aluminum cylinder is obviously,not because of improvement of the heat resistance,but the progress of cooling,and the casting result of technological progress.
With the advancement of science and technology, modeling technology has undergone tremendous changes.Special casting has been widely used in the production,such as investment casting,die casting,ductile iron casting,alloy casting,vacuum casting,precision casting.Sand casting,due to the development of new modeling materials,silicate sand,cement double quick sand,limestone sand, flowing self-hardening sand and resin sand,also gained wide application.New modeling techniques such as high pressure molding,lost foam casting, vacuum-sealed molding,magnetic-type shape,shell casting techniques are evolving in practice,so that the traditional sand casting process has a new vitality.But overall,the clay sand molding with greater flexibility, adaptability and economy,it is still the highest yield and the most widely used modeling technique so far.Types of casting are wet,dry,surface drying type,self-hardening sand,sand coated metal type.
The material characteristics of castings
1,steel is like carbon steel,are made of steel ingot smelting plant comes.
2,the steel ingot is melted again through the casting, the casting process which inevitably has defects such as change of composition, grain coarsening, easy to produce shrinkage, porosity and other casting defects, so the higher the rejection rate,mechanical performance than poor.
3,steel castings is made in accordance with the requirements of the designer's model casting,and can be made into complex shapes, there are special requirements of the parts
4,in machining,steel castings is already rough,you can go directly processed into parts.
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