large pellet machine ring die

Ring die pellet machine belongs to large pellet machine, which is widely used in the industrial making of biomass fuel pellets from wood waste or agricultural waste, and also fertilizer pellets. For different raw materials, the core part ring die is different. It plays an important role in increasing pellet quality and output (the pelleting step takes about 30-35% of total production energy consumption), decreasing energy consumption, and cutting down production cost (the wear and tear of ring die takes about 25%-30% of the whole production workshop maintenance cost), etc. Besides, ring die is the most easy to wear part in a large pellet machine. As a result, it is wise to know about the design of ring die, and learn about how to select, use and maintain it.

Design of ring die

Ring die rotate speed

The diameter of ring die for pellet machine manufactured by GEMCO is mainly 350, 420 and 508mm. The rotate speed of ring die relates to the geometrical parameter (number of roller, die hole diameter, die hole depth, etc.) of the pellet machine itself. According to the technical data obtained from some main pellet machine manufacturers and the test of sample equipments from other countries, for a ring die pellet machine that adopts 2 rollers, the proper ring die line speed is 4-8m/s.

This line speed directly affects not only the thickness of raw material in the pressing zone but also the time that raw material goes through die holes, ultimately influences the large pellet machine yield and pellet quality. Too high will decrease yield and pellet quality, while too low will produce good quality pellets, but the yield is also decreased.

Ring die material and heat treatment

Usually ring die is made from carbon structural steel, structural alloy steel, or stainless steel and processed by forging, stamping, cutting, drilling, heat treatment and other procedures. The material of ring die and every processing step affect its service life and pellet quality and yield.

• Carbon structural steel is mainly 45# steel, whose heat treatment hardness is HRC45-50, but its wear and corrosion resistance is poor. So it is no longer applied.
• Alloy steel is mainly composed of 20CrMnTi, which is processed by heat treatment of surface carburizing. Its hardness is >HRC50 and has good comprehensive mechanical properties. Its wear resistance is better than 45# steel (carbon steel), but it does not have good corrosion resistance. And the production cost per ton is higher than stainless steel. As a result, it is gradually disused.
• Stainless steel mainly applies 4Cr13, which has good rigidity and tenacity. The heat treatment is integral quenching. The hardness of this kind of steel >HRC50, and its wear and corrosion resistances are both good. Besides, they can be used for a long time and have low production cost. GEMCO large pellet machines apply stainless steel for the ring die to guarantee low price and best quality.

How to choose ring die for large pellet machine

The size of ring die for the large pellet machine is determined by the hour capacity you need, so here we only discuss the compression ratio, which is the ratio of the depth of die hole over its diameter.

To choose a right compression ratio for the ring die is quite important for large pellet production. The larger compression ratio it is, the higher density and smoother surface pellets will have. If the compression ratio is too low, the pellets will not be dense, and easy to break. The proper compression ratio depends on the natural status of the biomass raw material. So, for your own raw material, manufacturer will advise the most suitable compression ratio for your large pellet machine ring die.