The polygonal screen basket ensures continuous turning of the material, which significantly improves the separation of impurities. A square screen basket, as installed in the WIPA MD, offers a higher degree of cleaning compared to round screen baskets. More corners mean more friction and thus a better cleaning effect. Screen change has never been so easy and cost-effective as with the new screen design of the WIPA MD series. The screening elements are simple, inexpensive perforated plates, which are screwed onto a skeleton. All panels have the same dimensions, which saves storage and spare parts costs, as the elements can be interchanged or simply replaced. To change the sieve elements, only the clamping elements holding the sieves on the skeleton have to be loosened by means of 3-5 screws (depending on the size). In the intake area of the machine, the screening elements are subjected to greater stress than in the rear part of the machine, which results in higher and faster wear of these. Due to identical dimensions of the sieve plates in the front and rear part of the machine, it is possible to change the sieve elements from front to rear. This saves on spare parts costs, as the screen plates can be used for longer. Separate sieve elements additionally allow the use of different sieve perforations. Thus, for example, a larger screen perforation can be installed in the feed area of the machine than in the rear area of the machine. Sieve elements with thicknesses of 2-12 mm are available. The screen perforation can be individually adapted to the material. Round screen perforations between 2 and 3 mm are used as standard. However, other sieve bars with e.g. conical or angular perforations, as well as special sieve elements for e.g. the preparation of fibers or big bags can be supplied. The new screen design provides a much larger screening area than comparable equipment, significantly increasing separation, washing and drying results.