To sort products by size, traditional sieving machines are often used. Unfortunately, the pores of these sieves are easily obstructed or blinded. Therefore, we developed rotating drum sieving machines to overcome this difficulty. The pores of these rotating drum sieves are kept clean by a brush that is placed outside of the sieving drum. The rotating drum sieving machine can sort large amounts of bulk products with very little consumption of energy. Our rotating drum sieve works on the following principle: the bulk product is delivered to the first sieving drum via a vibrating duct. The particles whose diameters are smaller than the width of the mesh size can pass those and are separated from the rest. These past particles fall into a second sieving drum whose mesh size is smaller than those of the first sieve, and so on. The particles that are larger than the smallest mesh size are collected separately after they have passed the last sieving drum. Usually, two to four different sieving drums are used for the fractionation of bulk products. The use of a sieving drum is recommended for the sorting of volumes from 30-50 litres per hour upwards. For the sorting of very sensitive products or of products that are easily electrically charged when handled, we offer drum sieving systems that are optimized for these purposes including systems which can even sort wet products.

Apart from sorting according to size it, for certain products it is necessary to sort according to sphericity. A very efficient way to separate perfectly spherical product from those which are not is provided by sorting via our  Vibrational Sorting Table.