The working principle of the drum granulator is to tumble the materials in the rotating drum, usually in the presence of binders. The binder makes the fine particles sticky, allowing them to absorb more fine particles, forming clumps in a process called agglomeration. The tumbling action helps to round the agglomerates and form a homogeneous mixture.

Generally, in order to prevent materials from sticking in the cylinder, several flexible rubber sheet linings are installed along the circumference of the cylinder inner wall, and are fixed each other to the cylinder wall by flat steel battens and bolts. Several breathing holes are set behind each flexible rubber plate and on the cylinder wall to ensure that when the cylinder rotates upward, each rubber plate will automatically sag and deform due to its own weight and the gravity of the sticky material, and the sticky material will crack and fall off, thereby removing the sticky material on the cylinder wall.