The Ceramic sand (Also called Ceramsite sand) shell molding process mainly uses the coated sand with the Ceramic sand as the original sand and is a special casting process in which the sand shell is poured by the core shooting machine. Compared with the traditional shell molding process with silica sand resin-coated foundry sand, ceramic sand has the following advantages:
- Refractoriness
The refractoriness of Ceramic sand is above 1800℃, and the refractoriness of silica sand is generally around 1600℃, especially in casting of stainless steel, high-alloy steel and heat-resistant steel and other materials with high angular temperature. The advantages of using ceramic sand are very obvious. Resin coated foundry sand made of ceramic sand can effectively reduce sand sticking and other defects caused by insufficient refractoriness of molding sand.
The high refractoriness of Ceramic sand allows the sand mold to be non-sticky without painting refractory coating, which ensures the air permeability of the molding sand and saves the cost of coating and labor cost for the process.
- The amount of resin added and the amount of gas generated by the coated sand
Ceramic sand is a ball-shaped spherical foundry sand. When the coated sand is hardened, molding sands are bonding point to point. Comparing with the bonding of silica sand resin-coated sand is with side by sideway, the strength of the sand mold can increase more than 100% by adopting ceramic sand with the same consumption of resin.
In the same way, if we want to get the same sand strength adopting the two kinds of sands. The amount of resin added in the coated sand of Ceramic sand can be reduced by at least 30%-40%, and the amount of gas generated by the molding sand can be reduced by at least half (the new silica sand itself will also generate a certain amount of gas during casting). By using ceramic sand, coated foundry sand in shell-molding can effectively reduce the porosity of castings caused by the large amount of gas generated by the molding sand.
- Consumption of molding sand
The strength of Ceramic sand resin-coated sand is about twice that of silica sand, and the consumption of molding sand is generally reduced by about 30%-40%. According to the 1:1 ratio of iron to sand in the conventional shell molding process, to manufacture 1000 tons of castings, the consumption of Ceramic sand coated sand can save 200-300 tons of sand compared with silica sand coated sand, thereby effectively reducing the cost of molding sand and the amount of molding sand turnover.
- Casting quality
Silica sand often gets thermal expansion during the pouring process. The thermal expansion of new silica sand is 5.5×10-7/°C (0~1000°C), which is easy to form micro-cracks on the surface of the casting, which may even lead to defects of the casting in severe cases. The expansion rate of ceramic sand is 1.3×10-8/°C (0~1000°C), and the thermal expansion rate is much smaller than that of silica sand, which can effectively improve the quality of castings, reduce the rejection rate of castings, and reduce the time required for deburring repair during post-processing.
- Labor cost and production process
Ceramic sand is a kind of spherical foundry sand. Compared with the polygonal sand of silica sand, it has good fluidity. The sand shell is easy to fill during shell making, sand is filled tighter with ceramic sand. Defect castings can be effectively reduced due to insufficient sand strength.
When open the sandbox after casting, ceramic sand can shake out naturally. No need to remove sand by workers thus saving labor costs. According to the feedback from our customers, the cleaning staff can be reduced by more than 1/3, which effectively saves labor costs.
- Clean and environmentally friendly
Silica sand has the defects of weak and making many dusts, which not only causes serious pollution to the surrounding environment, but also easily causes occupational diseases such as pneumoconiosis to operators. Ceramic sand doesn’t break at high temperatures. This advantage can solve disease problems by developing a better working environment. In the meantime, avoids the disadvantages of finer and finer molding sand during repeated use. Thus ceramic sand is an eco-friendly foundry sand.