Introduction of Common Defects of Clay Sand Castings

The following common defects in clay sand castings are basically directly related to the old sand. Part of the problems that occur in the production process, clay sand old sand due to the thermal decomposition of each component in the process of recycling, changes in physical properties, such as not to be used, will make the quality of sand instability. The following are several common defects related to the quality of clay sand molding:

1. Air holes, less than pouring, cold isolation

Derivatives together become the fine powder of the old sand. If the content of micro-powder exceeds the limit, the micro-powder will block the gap of gravel, which will cause poor permeability of molding sand, and the water absorption capacity of ineffective clay is stronger than that of clay, thus taking water from clay. Therefore, when the content of invalid clay is more, the amount of water required to achieve uniform mixing will have to be increased, increasing the amount of water added to the sand, and to some extent, the amount of gas emitted from the sand will be increased. Due to the increase in the amount of gas emitted, the permeability will decrease, and the resistance of the liquid collected during casting will increase. It will inevitably lead to the formation of defects such as invasive pores, less than pouring, and cold isolation.

2. Poor surface finish (including sand holes, burrs, sand scarring)

A large amount of ineffective clay causes poor tensile strength, low toughness and poor permeability of molding sand. Increase the brittleness of the sand, so that the sand is easy to collapse the box, sand, sand particles are easy to fall during casting to form sand holes, burrs, slag scarring and other defects, thus affecting the quality of castings.

3. Sticky sand

4. Sand falling and box collapse during modeling

Dead clay has no cohesive force, and a large amount of dead clay causes poor molding sand, which makes the molding sand easy to collapse and drop sand.

5. Sticking mold

6. The phenomenon of porcelain in the old sand is more and more

7. Simple artificial sieve sand

Many enterprises adopt double sand system, simple manual screening, adding a large amount of new sand and more auxiliary materials mixed for surface sand, back sand is regularly screened, there are many problems.