Pellet mills are widely used in the feed industry, the biomass energy industry and pharmaceutical industry and many other fields.
As the core component of the pellet mill, the performance and service life of the ring die seriously affect the product quality and production cost. However, the problem of the ring die wears quickly and even cracks, which reduces the molding rate of the product and greatly increases the production cost.
It can be seen from the current situation of the industry that there is a large gap between the actual service life and the design life of the ring die. If the output of the ring dies drops significantly by more than 20% under normal production conditions, it can be determined that the ring die basically fails.
The ring dies inner wall is worn by micro-cutting usually caused by abrasive wear, as well as by fatigue wear, which causes the material on the surface to be lost faster. Die holes' inner walls are seldom worn, while the entrance part of the die hole wears mainly.
Hard impurities in raw materials may form wear between the inner wall of the ring die and the roller shell during the extrusion process, which causes the inner wall of the ring die to deform. When the diameter of the hard particles is slightly larger than the die roll gap, they will be pressed into the material surface or crushed to form irregular particles during extrusion, leaving obvious pits on the inner wall of the ring die.
The wear of the ring die near the feeding port is more serious than that of the other parts. This is because after the material enters from the feeding port, it has entered the working area between the die rolls without being evenly distributed by the scraper, so the material on the side of the feeding port will be relatively thick, which increases the working strength of this area, to speed up the wear rate of the ring die. Therefore, improved material distribution can help extend the life of the ring dies.
Ring Die Wear Improvement Suggestions
Impurities removal for raw materials.
The scraper is optimized to make the material evenly distributed in the granulation chamber, and prevent the ring die from being worn out prematurely.
Improve the material preparation process, reduce the wear effect of the material on the ring die, and increase the output of the pellet mill.
Improve heat treatment process. Improve the hardness of the wear layer on the inner surface of the ring die, improve the wear resistance of the ring die, thereby prolonging the service life.
