Sieves and screens used in grain milling

It is not always clear to someone unfamiliar with agriculture the significance of milling equipment when preparing feed for animals and birds. But any village resident knows that unground grain is poorly digested, resulting in a significant portion directly going into manure. Ground feed is required for almost all types of farm animals and most birds. The milling process is particularly important for preparing compound feed mixtures, the technology involves not only grinding the grain component, but also pelleted raw materials, as well as mineral additives and bran.

Milling levels and quality determination

Sieves and screens for mills are selected according to the feed mixture recipe, and three levels of milling are distinguished, determined by the diameter of the matrix holes:

1. for coarse grinding from 6 to 8 mm;
2. for medium - from 3.5 to 5 mm;
3. for fine (fine) - from 2 to 3 mm.

When using ground grain in its pure form, coarse grinding is primarily used for feeding poultry, specifically adult birds. When raising cattle and pigs, medium-ground grain is more commonly used, and in some cases, pig farming technology requires the use of finely ground grain. Pet food for dogs and cats, specialized (extruded) fish feeds, and pelleted pre-starter feeds for piglets are produced using fine-ground grain.

The quality of grinding is determined by testing residues on laboratory sieves with different hole sizes. When fine-ground grain is sieved through holes of 2 mm diameter, the residue should not exceed 5%; for medium-ground grain with 3 mm holes, the normal indicator is less than 12%. Coarse-ground grain leaves up to 35% of the total mass when sieved through the same holes, and when the hole diameter is increased to 5 mm, the residue from coarse grinding should decrease to 5%.

Advantages of perforated sheet

The milling technology imposes significant loads on all components of the milling unit, therefore special requirements are placed on sieves regarding strength and durability. Perforated screens, made from perforated sheet - the optimal choice, sheet material possesses the necessary strength, and holes arranged at equal distances from each other and a flat surface ensure even sieving across the entire working surface. Using perforated screens significantly increases the mill's productivity and improves the quality of the finished product.

Depending on the application field, sieves for mills can be manufactured from cold-rolled and hot-rolled steel sheets, from stainless steel and galvanized steel sheets, as well as from aluminum alloys. Items made from stainless steel and aluminum are more commonly used in food production, while for agricultural purposes, mills are equipped with components made from black or galvanized material. The holes in the sheet can have various shapes, and the choice of hole shape determines the purpose of the sieve and the structural features of the mechanism.