Differences in Particle Quality and Application Effects between Flat Die Granulators and Ring Die Granulators

Nov 26, 2025

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The physical qualities of pellets vary significantly. In terms of density, pellets processed by flat die pellet mills have a lower density, typically between 1.1-1.3 g/cm³, with a relatively loose structure and a lighter feel; pellets processed by ring die pellet mills have a higher density, typically between 1.4-1.6 g/cm³, with a denser structure and a heavier feel. Regarding soaking resistance, flat die pellets have a shorter soaking time, typically between 10-20 minutes, suitable for direct consumption by livestock and poultry but not for aquaculture; ring die pellets have a longer soaking time, reaching 30-60 minutes, meeting the needs of aquatic animals for slow feeding in water and reducing uneaten feed contamination. In terms of formation rate and uniformity, flat die pellets have a formation rate of approximately 85%-90%, with uneven pellet size, a rough surface, and a tendency to break; ring die pellets can achieve a formation rate of over 95%, with uniform pellet size, a smooth surface, and a breakage rate of less than 5%. In terms of storage stability, ring die pellets have high density and low moisture content (usually below 12%), making them less prone to moisture absorption and mold growth during storage, with a shelf life of over 6 months. Flat die pellets, on the other hand, have relatively higher moisture content, making them more susceptible to moisture absorption and mold growth during storage, with a shelf life typically less than 3 months.

The nutrient retention and digestibility of pellets also differ. Flat die pellet mills operate at lower extrusion temperatures, typically between 70-90℃, resulting in less damage to heat-sensitive nutrients (such as vitamins and amino acids) and a relatively high nutrient retention rate of approximately 85%-90%. However, due to their loose structure, the digestibility of flat die pellets by aquatic animals is relatively low, at approximately 60%-70%. Ring die pellet mills operate at higher extrusion temperatures, typically between 90-110℃, resulting in greater damage to heat-sensitive nutrients and a nutrient retention rate of approximately 80%-85%. However, due to their denser structure, starch in the feed is fully gelatinized, and proteins are fully denatured, leading to a higher digestibility of ring die pellets by aquatic animals, at approximately 75%-85%. Actual farming cases show that broilers fed with ring-die pellets experienced a feed conversion ratio (FCR) reduction from 1.8:1 to 1.5:1, shortening the time to market by 3 days. Shrimp fed with ring-die pellets showed a 20%-30% increase in weight gain and a 0.3-0.5 decrease in feed conversion ratio.

The application effects vary significantly across different farming scenarios. In livestock and poultry farming, flat-die pellets meet basic feeding needs and are suitable for small-scale farmers, but their loose texture and tendency to generate dust can lead to respiratory diseases in livestock and poultry with long-term use. Ring-die pellets, with their dense structure and low dust generation, reduce the incidence of respiratory diseases and have high digestibility and absorption rates, making them suitable for medium- to large-scale livestock and poultry farms. In aquaculture, flat-die pellets lack sufficient foam resistance and cannot meet the requirements; ring-die pellets are the only option. In pet farming, ring-die pellets offer better uniformity and palatability, increasing pets' appetite and providing balanced nutrition, making them suitable as a staple pet food. In ruminant farming, ring die pellets can effectively process high-fiber raw materials. The dense pellet structure can prolong the residence time of feed in the rumen, improve digestion and absorption, and the farming effect is better than that of flat die pellets.