On alkali phenolic resin sand
Sodium silicate self-hardening sand, furan resin self hardening sand and alkali phenolic resin self hardening sand are widely used in the production of steel castings. With the discovery and popularization of Fused ceramic sand and the improvement and maturity of old sand recycling technology, alkali phenolic resin self hardening sand gradually shows its advantages in mass production of steel castings, and increasingly becomes the choice of molding process for new and rebuilt steel casting plants.
Advantages and disadvantages of alkali phenolic resin sand
Advantages of alkali phenolic resin sand: during pouring and cooling, no nitrogen, phosphorus, sulfur and other elements that can enter the molten steel and affect its quality are produced, so there are basically no defects of sulfur infiltration and needle like pores in the surface layer of steel castings produced by furan resin. In the process of sand mixing, molding, core making, pouring and sand cleaning, toxic and pungent gases are rarely released, which has little impact on the operating environment. Alkaline phenolic resin is strongly alkaline, and the acid consumption value of raw sand is not high. Alkaline raw sand can be used, such as chromite ore sand in large steel castings.
The main problems of alkali phenolic resin sand are: the strength of alkali phenolic resin is relatively low, and the amount of resin added in molding sand is large, resulting in high production cost. The regeneration rate of alkaline phenolic resin used sand can only reach about 70 ~ 80%, which increases the amount of new sand, increases the discharge of old sand, increases the cost and pollutes the environment. The shelf life of alkali phenolic resin is relatively short, generally within 6 months.
What benefits will fused ceramic sand bring when it is applied to alkali phenolic resin sand?
1. Fused ceramic sand is spherical with smooth surface. Under the same strength requirements, the amount of resin can be reduced by 30-40% compared with the use of silica sand, and the air emission of mold / core sand can be greatly reduced.
2. Fused ceramic sand has high fire resistance and is neutral. It can be used for casting all kinds of casting alloys, including stainless steel, manganese steel and chromium steel.
3. Fused ceramic sand has good fluidity and is easy to fill. It can make sand cores with complex shapes and small local cross-sectional area;
4. Fused ceramic sand has high strength, low crushing rate, high durability and high regeneration recovery rate, and the regeneration recovery rate is as high as 98%.
5. Fused ceramic sand has a low expansion coefficient, which can reduce casting defects such as veins caused by sand (expansion);
6. Environmental protection advantages: less casting waste (waste sand) and less waste gas are produced, which is known as the green casting material of the 21st century.
7. Fused ceramic sand also has the advantages of high thermal conductivity of core sand, good air permeability and good collapsibility after pouring.