Development of Lost Foam Casting Process
Lost Foam Casting (LFC) is a new casting technology with precise forming, which has been developed rapidly in recent years. Compared with traditional sand casting, this technology is more competitive in the market. The lost foam casting process is showing its strong vitality and is known as ‘the casting technology of the 21st century’ and ‘green revolution of foundry industry’.
Why use lost foam to produce cooling staves
The cooling stave is an important part of the blast furnace cooling system, which is installed in the body, waist, bosh, hearth and other parts of the blast furnace.
It plays an important role in supporting refractory materials, cooling furnace shell and maintaining reasonable furnace shape. The cooling stave not only bears high temperature, but also bears the grinding of furnace burden. The erosion of slag and the erosion of gas flow must have good comprehensive properties such as thermal strength, thermal shock resistance, and resistance to rapid cooling and heating.
The material and performance of the cooling stave determine its working life and even the life of the blast furnace shaft. The production situation of iron and steel enterprises at home and abroad proves that one of the keys to the longevity of blast furnace is to realize the longevity of cooling stave.
The traditional casting method is often used for the manufacture of cooling staves. Now resin sand casting is widely used, but the operation is complex, which is difficult for workers, and it is difficult to meet the market demand due to high operation level, high mold cost, long production cycle and low production efficiency.
Dry sand lost foam casting, the process can not only simplify the operation, shorten the production cycle and reduce the cost, but also improve the surface quality of castings and production efficiency.
However, problems such as shrinkage porosity and shrinkage cavity, sand sticking on the surface, box collapse and cold lap wrinkle often occur in medium and large castings produced by lost foam process.
The key factors of these problems are the quality of white mold, coating performance, gating system design, vacuum degree and molding pouring mode.
Fused ceramic sand helps lost foam casting
Fused ceramic sand of 20 ~ 40 mesh is used, the thickness of bottom sand is 200 mm, and it is vibrated and leveled. Use special lifting tools to lift the model into the sand box, and connect the pouring system and add sand and vibrate in 3 ~ 4 times.
In production practice, appropriate EPS module is selected, fused ceramic sand and qualified coating are used, and reasonable gating system and related molding workers are designed to get the planned target.
To sum up, it is completely feasible to produce blast furnace cast iron cooling stave by lost foam process and has great advantages.