Casting sand has the following performance:
1) breathable type
After the high -temperature metal solution is poured into the casting, the type is full of a large amount of gas. These gases must be discharged smoothly from the casting shape. The type of sand can make the performance of the gas through the permeability. Otherwise, it will cause defects such as pores and insufficient watering. The permeability of the casting is affected by factors such as particle size, clay content, moisture content, and sand -shaped tightening. The finer the granularity of the sand, the higher the clay and moisture content, the higher the tightening of the sand, and the worse the breathability
2) strength
The ability to resist external force destruction is called strength. Sand must have sufficient strength to cause collapse in the process of shape, handling, and boxing, and it will not destroy the cast surface when pouring. The strength of the sand should not be too high.
3) Fire resistance
High -temperature metal liquid has a strong heat effect on the casting shape. Therefore, the ability to resist high temperature and thermal effects is to resist fire resistance. If the fire resistance of the modeling material is poor, the castings are prone to sticky sand. The more SIO2 in the sand, the larger the sand particles, the better the fire resistance.
4) Pooplastability
Finger sand is deformed under the action of external forces, and after removing the exogenous force, it can maintain the existing shape. The shape of the modeling materials is good, the shape is convenient, and the shape of the sand is accurate and the outline is clear.
5)
When the casting is condensed, the volume is shrinking. The type sand should have a certain ability to be compressed, which is called the concession. The coordination of the sand type is not good, and the castings are prone to internal stress or cracking. The firmer of the sand, the worse the concession. Adding wood chips and other objects to type sand can improve the concession.