1. Feeding way: ring die pellet mill adopts machine forced feeding, materials enter the granulating chamber with high speed rotary and distribute through scraper to ensure feed evenly; while the flat die depends on the materials weight, it directly enters into the suppress room, it can feed evenly.

2. Pressure: in the same diameter mould, the pinch roller of ring die is limited by the mould diameter, so the pressure is restricted; however, the flat die can add the inside the bearing space, choose a big bearing to increase the bearing capability, which not only improve the press power of pinch roller, but also prolongs the life.

3. Discharging way: ring die belongs to high rotary speed, the materials percentage of damage is high, while the percentag eof damage of flat die is low.