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Why do the biomass pellets produced by the pellet machine have cracks?

In production, wood pellets with abnormal appearance sometimes appear, and experienced wood pellet machine manufacturers will know what causes this situation and can quickly eliminate it. For less experienced or new wood pellet producers, sometimes you can't find the crux of the problem, only ask the help of the pellet machine manufacturer. The following pellet machine manufacturer will explain why there are cracks in the pellets produced by the pellet machine:

Why do the biomass pellets produced by the pellet machine have cracks?(图1)

1. The wood pellets are curved and have many cracks on one side.

This phenomenon is usually produced when wood pellets leave the ring mold. In production, when the position of the cutter is adjusted far from the surface of the ring die and the edge is blunt, the particles are easily broken or torn by the cutter rather than being cut when being extruded from the die hole. At this time, some wood chips are bent. There are many cracks on one side and the other side. Such wood chips tend to break from these cracks as they enter the cooler for cooling or transportation, resulting in excessive production of wood pellets or too short particles.


2. Horizontal cracks traverse the entire wood pellets

Similar to the phenomenon in Case 1, the crack occurs in the cross section of the wood pellets, but the particles are not bent. This may occur when granulating fluffy wood pellets containing more fibers. Such wood chips are often used to squeeze wood chips into the granulation holes of the ring mold. Since the fibers contain fibers longer than the pore diameter, when the particles are extruded, the particles are traversed in cross section due to the expansion of the fibers. Produces the appearance of Bark-like wood pellets.


3. Wood pellets produce vertical cracks

Some customers in the production process, due to the choice of dryer type, can not evenly dry the wood chips, resulting in uneven moisture content of the raw wood chips, after the ring die compression granulation, due to the role of water and the raw materials themselves The elasticity is bounced off, creating vertical cracks.


4. Wood chip particles generate radiant cracks from a source point

The main reason for this is that the wood chips contain relatively large wood chips. Raw materials of similar fiber content will cause them to squash each other when granulating, such as the presence of larger fibers, which affect the interaction between the fibers. He does not soften easily like other finer materials, and when cooled, due to the difference in softening degree, the difference in shrinkage is caused, resulting in radiant cracks.


The inner wall of the ring mold aperture is inconsistent. Due to the inconsistent mold hole finish, the resistance and squeezing force of the granules during extrusion are different, and the color changes are inconsistent. In addition, some of the ring mold holes have burrs on the wall, and the particles may scratch the surface when extruded, so that the surface color of the individual particles is different.