What are the characteristics of coated sand so that steel castings foundries like it

 Coated sand is a commonly used casting process in cast steel foundries, and its application range is also very wide, and the process methods are also different. Whether it is core making or modeling, the basic process requirements for coated sand casting are: the heating temperature should be between 200-300, the curing time should be between 30-150, and the sand shooting pressure should be between 0.15-0.6Mpa, except for wet manual casting. The specific parameters need to be adjusted according to the type, type and weight of the core, its complexity, and the type of coated sand. The principle of adjustment is: if the sand core shape is simple, good fluidity or coated sand particle size is coarse, you can choose a lower injection pressure; for a thinner sand core, you need to choose a lower heating temperature; when the heating temperature is lower, The manufacturer should appropriately extend the curing time, and vice versa.

So what are the characteristics of coated sand for steel casting? Next, Xiaobian will give you a brief introduction:

Coated sand raw material

1. Coated sand has good fluidity, and the type and core made by it have clear outline and compact structure, which can make more complex sand cores, such as cylinder liner core and cylinder head.

2. Coated sand has strength properties suitable for real objects, so it can be made into high-strength shell core coated sand, medium-strength hot core box coated sand, and low-strength non-ferrous alloy coated sand.

3. The coated sand used in the steel casting plant can cast a sand core with good surface quality. In the case of less or no coating, can obtain better surface quality of steel castings, surface roughness RA = 6.3~12.5 microns, dimensional accuracy CT7 ~ CT9.

4. Coated sand has many advantages, less casting defects. However, the same coated sand has high cost and high energy consumption, which will produce irritating odor in the process of modeling, core making and casting, and may cause caking and other problems when stored for a long time in high temperature or high humidity season.

5. The coated sand has good collapsibility and the casting is easy to clean.

The sand core has strong anti-moisture absorption ability and long existence time, which is more conducive to storage, transportation and use.

Coated sand raw material

China's coated sand technology began in the mid-50s and stopped in the 1960 s. In the 1980 s, due to the demand for products in the machinery industry and the rapid development of the industry, higher requirements were put forward for the quality of castings in the industry, which promoted the rapid development of coated sand production and application technology. At present, coated sand has become an indispensable casting process for steel casting foundries.

Simply put, the coated sand is sand or core sand whose surface is covered with a layer of solid resin film before modeling. There are two coating processes: cold method and hot method: cold method dissolves resin with ethanol, and in the sand mixing process, adding tropics, so that the two are coated on the surface of sand particles, and ethanol volatilizes to obtain coated sand; Hot method preheats the sand to the corresponding temperature, adds resin to melt it, stirs the resin to coat the surface of sand particles, adds wuluo aqueous solution and lubricant, cools, crushes and screens to obtain coated sand.