The machine is mainly used for the metal beneficiation production process, according to the different speed of mineral particles settling, the 14-325 mesh ore size classification, can also be separated from the mine or used for sludge dewatering. According to the different spiral number, there are single helix and double helix points, as well as the weir-and sinking-type distinction, such as the overflow side weir higher than the screw axis centerline, and below the overflow end of the spiral diameter Weir type; such as the overflow side weir higher than the spiral axis of the center line, while also higher than the overflow end of the spiral diameter of the sinker type: weir-type grading machine is generally used for 100 mesh size below Of the classification; sinking classifier is generally used for 200 mesh size grading. C-behalf of the sinking; G-behalf of the weir-type; 2F- on behalf of the double helix; F- on behalf of a single spiral.