During screening, materials are partially cleaned of foreign substances and divided into different fractions. Specified grain sizes are used in the further sorting process for better sorting quality. The purpose of sieving is also to separate particles from a granular substance that are smaller than the sieve opening from those that are larger. This is not as easy as it sounds and the difficulty increases when the opening gets smaller. Sieving can be done dry or wet, depending on the material, different sieve inserts are required.