Roller Shells of Pellet Mills
Pellet mills are now familiar to many people and they can make feed pellets, wood pellets and other pellets. However, some people may not be clear about how pellet form its shape.
For a ring die pellet mill, there is a single or double roller shells installed on an eccentric rotating shaft. When feed is forced through the die holes at a high speed, the mutual pressure between the ring die and roller shells will work to overcome the resistance. Under their effect, materials become tight layers. Then they can be further processed as pellets.
Also, the roller shells only turn as feed between rolls and pellet press dies develops friction. Only with friction, we can see roller shells operate in extremely harsh conditions. During the working process, massive forces are transferred from the die face through the bearings to the roll support shaft. The friction thus causes fatigue crack on the surface. As a result, the fatigue crack occurs in a certain depth later and service life of the shell will be longer accordingly.
The roller shell is the surface where raw materials are pressed against the die. Since the roller shells and the die are closely related in the pelletizing process, the life of roller shells is quite crucial for the performance of the die. A good roller shell should be made of alloy or stain. There are four roller shells: tungsten carbide roller shells, corrugated roller shells, indented roller shells and coin slotted roller shells. Among them, roller shells with corrugation are the most popular ones, since they can reduce slipping and offer resistance to plugging the die during pelletizing process.
When choosing a pellet mill, roller shells must be taken into consideration. The suitable roller shells should be designed to match the life of the die.