How to judge the quality of die in pellet plant

In addition to the huge mechanical stress, the die of pellet plant would also be affected by the heat, which would cause thermal stress. The die steel used in the pellet machine is required to have high hardness, strength, red hardness, abrasion resistance, toughness as well as good high temperature strength, thermal fatigue resistance, heat conductivity, corrosion resistance and high hardenability to ensure the consistent mechanical properties of the whole section. In addition, it should also have good manufacturability, such as small heat treatment deformation, good processing performance, good repair welding performance and stable size and shape, etc. 



Therefore, the die of pellet plant should use medium carbon alloy steel with moderate carbon content. More alloying elements need to be added in steel smelting to become eutectoid or hypereutectoid steel, so the price is expensive, which is several times higher than that of ordinary carbon steel. Therefore, when choosing pellet plant, users should not only pay attention to the price, they should be more concerned about the quality of pellet plant, especially the quality of the die in pellet plant.
 
Then, how to judge the quality of die in pellet machine?
1. Check whether the surface processing of die is fine: the die of high quality pellet plant is produced by CNC machining center, so the surface finish is higher, the texture of cutting tool is uniform and the surface is flat and smooth, while the common die is produced by ordinary machine tool with low surface roughness, uneven texture of tool and rough surface due to the need to save the processing costs.
2. Check whether the shape of die is completely consistent: the die of high quality pellet plant is processed by CNC machining center. The size of all dies is clamped once and processed by unified program. Its high accuracy and consistency of processed products is unmatched by ordinary machine tools. The consistency of die ensures the uniform molding pressure, stress and the interchangeability of die, which makes the replacement and maintenance of the die more convenient.
3. Check the hardness of die: the die of high-quality pellet plant is made of special alloy steel through complex multiple heat treatment process and the hardness can reach the Rockwell hardness 60 degrees. All kinds of machining tools, including drill and tap, can not cause the slightest damage to it. Thus, it is quite difficult for straw and other biomass materials to make the die wear. While the hardness of ordinary carbon steel die is only 45 to 50 degrees so that the drill and tap can make the die damaged.
4. Check the strength and toughness of die: the steel used in the die of high quality pellet plant is processed with repeated forging and its molecular arrangement is more compact and the tissue density has been improved greatly. The strength toughness is 2 ~ 3 times of ordinary carbon steel plate so that the die of pellet plant would never deform under high strength and stress state for a long time.

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