The grading cylinder is used for classifying and separating the rice according to its thickness. It can be used for the selection of all seeds which require to be processed very accurately or which have to be divided into various fractions (sunflower, soya, beans etc.).

The cylinder consists of a rotating drum which is lined with a number of replaceable indented graders. The entire unit is protected by an external metal fairing the base of which is formed by a number of autonomous delivery chutes for the separate collection of the product coming from each calibrator sector. Each hopper has a deviation valve which allows the flow of material to be directed to one of the underlying delivery chutes. The cylinder is suitably tilted to permit the seeds to move forward within it.

The quantity of seed which enters the cylinder due to the effect of the inclination and rotation, moves along the drum and for the entire distance it remains constantly in contact with the calibrators. The desired classification is obtained by varying the size of the holes in the calibrators.

From the delivery chutes the broken parts of seeds are bagged or sent on for further processing. The cleanliness of the calibrating sectors is guaranteed by a series of rotating brushes which continuously operate on the said sectors.