portable diesel air compressor

It is important to know that the shape of the sand has an important impact on the surface finish of the casting. Circular sand is better than triangular sand because the triangular sand has a large gap, which is easy to lead to defects such as porosity; According to the nature of the casting, the sodium silicate quartz sand is selected to form a spalling layer, and combined with the characteristics of cooling and shrinkage of the casting, the surface defects are reduced. Coating a protective layer on the surface of large castings, such as the film on a coated sand mold, can improve the surface finish of the sand mold and reduce the surface defects of the casting.  

...