Brief Introduction of 1. Ceramsite sand
Baozhu sand, also known as electrofused ceramsite, is a high substitute for quartz sand.
Ceramsite sand microscopic photo:
The advantages of quartz sand are widely distributed and low cost; but its disadvantages are also quite obvious: first, the expansion coefficient is large, and the casting precision is low; second, the surface of the casting is seriously sticky sand, and it is difficult to clear sand. The reason is that Shi Ying will have a variety of homogeneous and heterogeneous crystals at different temperatures, with large volume changes. Limited by the refractoriness (the refractoriness of quartz sand is between 1400-1700 ℃), the local parts of the casting (holes, grooves, and parts where hot joints are concentrated) stick to sand seriously, making it very difficult to clean. The above disadvantages are particularly serious in the production of large steel castings.
Ceramsite sand can overcome these shortcomings, thereby greatly improving the quality of castings.
Baozhu sand is made of high-quality bauxite as raw material, through calcination, electric melting, granulation, screening and other processes.
Physical and Chemical Properties of 2. Jewel Sand
Characteristics of 3. jewel sand
The thermal expansion coefficient is small, the performance can be comparable with zircon sand, with its preparation of sand, castings will not produce expansion defects.
The sand is spherical, with good fluidity, easy pounding and good air permeability.
The surface is smooth and the structure is dense, so that the adhesive can cover evenly.
Ceramsite sand is a neutral material, acid and alkali binders can be used.
. Good recycling and regeneration performance, high cost performance
Compared with chromite sand and zircon sand, its price is only 25-50% of zircon sand and chromite sand. At the same time, because the sand particles are spherical and its surface area is small, the amount of resin added can be reduced by 30-50%, the amount of water glass added is less than or equal to 4%, and the casting defects caused by the binder are reduced, and the finished product rate of the casting is improved.
High fire resistance, easy to collapse
The mullite phase of the jewel sand is much higher than that of the sintered product and has good fire resistance
. Thermal conductivity, good stability, no cracking
. Wide range of applications
Polishing and cleaning of water glass sand, resin sand, precision casting and copper and aluminum parts
Comparison of main properties of jewel sand, chromite sand and zircon sand:
Application of 4. jewel sand in large castings
At present, the Ceramsite sand is widely used in resin sand (furan resin, phenolic resin), water glass sand (organic grease, CO2 hardening), coated sand. Suitable for all kinds of metal castings, such as: carbon steel, alloy steel (high manganese steel, high chromium cast iron), cast iron, cast copper, etc.
After long-term exploration with foundry manufacturers, it is concluded that the thickness of surface sand should be 10-20mm (tight pounding thickness); For complex shapes, thick parts and corners, the thickness shall be appropriately increased, and ordinary quartz sand shall still be used for back sand.
The sand can also be mixed with quartz sand, the proportion according to the size of the casting, steel change and change, also achieved non-stick sand, easy to collapse effect.
Application Prospect of 5. Jewel Sand in Automobile Parts
For a long time, the automobile industry has been the largest market of the foundry industry. In recent years, the development of my country's automobile industry has continuously driven the foundry industry into a new period of development, and its rapid development has also led to the rapid expansion of the foundry industry market. And give it broad development prospects.
Application conclusion of 6. jewel sand
Baozhu sand is a kind of non-Shi Ying artificial sand, which is suitable for various casting methods. For example: V method, VRH, lost foam, investment mold, general sand mold (clay sand, sodium silicate CO2 hardening), resin sand, etc., suitable for casting production of various binders and various metal materials, not only can greatly improve the casting quality, but also sand cleaning is easy, and sand mixing process is simple and convenient (large-scale steel foundry single-casting plant small batch local sand, A small amount of sand manual mixing can be), for most castings can save coating, especially suitable for the production of high quality requirements of castings.
It is worth noting that in the use of water glass CO2 hardening sand, the core and type of blow-dry should not be dried in the kiln (such as drying must control the heating speed). With the development of the foundry industry and the requirements of social environmental protection, more and more manufacturers will use Ceramsite sand partially and completely. It has been hailed as an environmentally friendly (GREEN BEADS) casting material and has a good prospect of promotion and use. Jewel sand effectively solves the problems of high casting cost and poor casting quality.
Lost foam casting enterprises have been affected by many factors in recent years, resulting in the production of castings finished product pass rate is not high, among which, the high production cost of castings, high defective rate, low quality and other characteristics have become the three giant mountains in the domestic lost foam casting enterprises. How to solve these problems and improve the cost performance of casting products as soon as possible has become one of the primary tasks of domestic casting enterprises. As we all know, the choice of medium-sized sand in the casting process is a crucial link in the whole process. Once the sand is not properly selected, the whole situation will be affected. Therefore, lost foam casting enterprises should make more efforts in the selection of molding sand.
According to relevant data, at present, most foundry enterprises in China have made improvements in the selection of molding sand, abandoning the traditional low-cost quartz sand or magnesium olivine sand and adopting a new type of Baozhu sand to improve the casting problem. This new type of sand is the product of school-enterprise combination, which focuses on the advantages of high fire resistance, good fluidity and high air permeability, and solves the defects in casting production to a certain extent, therefore, it has been widely concerned by the international foundry industry and has become the new favorite of lost foam casting. The three major problems of casting cost, defective rate and quality of lost foam casting enterprises have been effectively alleviated, and jewel sand has also been loved by many enterprises.