The development of foundry binder has experienced a long historical process, which has developed from the initial clay binder to other inorganic, organic or inorganic and organic combination of a series of binders. The basic material of clay mold (called pottery mold in ancient times) used in ancient China is clay with strong bonding ability. With the development of technology, there are a large number of sand particles in the clay mold, and gradually the sand is the main material, so the clay becomes the binder. Clay is even still widely used today.
Later, a variety of inorganic and organic additives appeared, such as vegetable oil, rosin, dextrin, sodium silicate, etc. In 1943, German J. Croning invented using phenolic resin as binder to manufacture thin shell sand mold. L. Petrzela from Czechoslovakia in 1947 uses water glass as molding sand binder, which is hardened by blowing CO2 gas to make sand mold and core. The application of these two kinds of binders opened up a new way for the chemical hardening of sand mold and core. Since the late 1950s, various countries have successively adopted furan resin binder, and the core can be hardened after 1 ~ 2min of core making in the heated core box.
The application proportion of organic, inorganic and clay binders in various core making and molding methods has also increased with the advancement of the times. A survey was conducted abroad, and the proportion of clay materials used in modeling was about 63%, using other inorganic binder materials accounted for 13%, using organic binder materials accounted for 24%. In the core making, in terms of the method, firstly, various core making methods using inorganic binders are integrated, accounting for 21.6% of the total. Cold synthetic resin accounted for 26.3%, while the heat hardening method accounted for 51.6%.
As an important part of sand casting, the cost of binder also accounts for a large proportion. The use of fused ceramic sand, because it is close to the spherical shape, will greatly reduce the use of binder, so as to achieve the effect and requirements of cost saving.
Major Parameters of Fused Ceramic Sand
1. Shape: Sphere
2. Angle Factor: ≤1.1, very spherical
3. Bulk Density: 1.95-2.05 (g/cm3)
4. Refractoriness: ≥1790℃
5. Thermal expansion: 0.13％ (10 minutes at 1000℃)
More Advantages of Fused Ceramic Sand Are as Follows
1. Solid sphere: The shape of Fused Ceramic Sand is spherical with smooth surface and less surface area and offering a very good flow ability and filling ability. To compare with other sands else, less binder is used at the same mold strength and higher venting ability. It also offers the excellent collapsibility.
2. Lower thermal expansion rate: Fused ceramic sand makes the dimensions of castings better, less crack and defect and higher output.
3. Lower breakage rate: Fused Ceramic Sand has a higher density and a very lower breakage rate at the reclamation. It makes a better reclamation rate to reduce the waste sand to be favor to the environment.
4. High refractoriness: Fused ceramic sand’s major chemistry is Al2O3. PH appears neutral. It belongs to the refractoriness of the series of Aluminum and Silicon which has a very good refractory performance. It is suitable for all kinds of metal and alloy castings.