Why casting is so important？
Casting is an important method to provide blanks for the machinery industry, and it plays an important role in the "made in China 2025" strategy. However, casting is a highly polluting industry, which will bring problems such as air pollution and solid waste pollution in the process of casting production. With the increasingly stringent requirements of environmental protection, it is of great significance to develop green and pollution-free casting materials and technologies. Casting materials mainly include raw sand, binder, curing agent, additives and coatings, which play an important role in casting production, directly affect the quality and production efficiency of castings, and are also the main source of pollutants. In the whole sand-casting production, the organic matter in the casting material (resin binder, curing agent, coal powder, etc.) burns or volatilizes under the thermal action of high-temperature metal liquid, producing harmful gases.
Recycling procedures make a great contribution to environmental protection
At present, foundry waste sand can be recycled in foundry enterprises through recycling technology, but about 20% of the waste sand is still discarded. Due to the small particle size and complex composition of casting waste ash, it is difficult to recycle. Generally speaking, most of the pollutants produced in the casting process come from casting materials, which play a decisive role in the cleaner production of foundry. Starting from the raw sand, binder, coating and other casting materials for casting, if they can be recycled and meet the new progress of green environmental protection casting materials, this is the future development trend of environmental protection.
The use of fused ceramic sand is beneficial to environmental protection and improves the working environment of foundry workers.
Artificial special sand (Fused ceramic sand, ceramic sand, etc.) has a wide application prospect in green casting because of its round particles, high controllability, and good regeneration effect, which meets the development requirements of green casting. However, at present, the application of artificial special sand in the domestic market is less, so we should strengthen the research of artificial special sand, improve the output of artificial special sand, reduce the cost, and promote its application in China. In addition, because of the good fluidity and permeability of Fused ceramic sand, its application in lost foam casting process can improve the quality and production efficiency of castings, and improve the working environment.
The rapid popularization and application of Fused ceramic sand benefits from the following casting process advantages:
1. Nearly spherical particles, smooth surface - low binder consumption, low gas generation, good fluidity, good filling, and good collapsibility after pouring.
2. Low thermal expansion rate - the thermal expansion rate of Fused ceramic sand is comparable to that of zircon sand, which is 1/5 of that of silica sand1/2 of chromite sand. The castings produced have high dimensional accuracy, few defects and high yield; Using Fused ceramic sand to prepare mold and core sand can basically eliminate the expansion defects such as casting veins.
3. Good crushing resistance - Fused ceramic sand has compact material, strong crushing resistance, and low crushing rate when reused, which greatly improves the recycling rate of core sand, reduces the discharge of waste sand, and is conducive to cost reduction and environmental protection;
4. High fire resistance - reduce sand sticking, reduce cleaning workload, and improve the surface quality of castings. At the same time, it is especially suitable for the production of sand cores and steel castings with complex shape and small cross-sectional area;
5. The bulk density is relatively small - the bulk density of Fused ceramic sand is about 2 g/cm3, which is less than 2.5-2.9 g/cm3 of chromite sand. The manufactured sand core is lighter and easy to handle, which can reduce the use of core sand.
6. Good process applicability for binder and casting alloy - the main component of Fused ceramic sand is Al2O3, which is a neutral material. Acid and alkali binder systems can be used, and it is suitable for all kinds of casting alloys.
7. Fused ceramic sand has a wide range of grain size - it can be mixed according to any combination according to requirements to meet different needs of customers.
8. High cost performance - the price of Fused ceramic sand is about 1/3 of that of zirconium sand. Although the unit price of raw sand is higher than that of silica sand, comprehensive evaluation shows that under certain conditions, the use of Fused ceramic sand not only has certain economic benefits, but also has significant environmental benefits.