Screening machine used for big volumes and complex processes. It is suitable for classifying powder or granule product particles by size or for checking them before processing. The product is conveyed by a metering screw that enters the sieving chamber. There, the slightly inclined blades of the shaft push it (by centrifugal force) the nylon screen mounted on a stainless steel support. Fine particles pass through the screen whereas bigger particles are separated and taken to the discharge outlet.