The pellets of the wood pellet machine are bent and have many cracks on one side, which usually occurs when the wood pellet machine leaves the ring die. In production, when the cutting position is far away from the surface of the ring die and the knife edge is blunt, when the particles are extruded from the die hole, they are easily touched or torn by the cutting knife instead of being cut. At this time, some sawdust particles are bent on one side, and many cracks appear on the other side.

The wood pellet machine produces radial cracks from one source point. The main reason for this situation is that the wood pellet machine contains relatively large wood chips. Raw materials with similar fiber degrees can only be extruded and fused with each other when pelletized. For example, large fibers will affect the interaction between fibers. It is not as easy to soften as other finer raw materials. When cooling, due to the different degrees of softening, the difference in shrinkage will result in differences in the amount of shrinkage, resulting in radial cracks.

Horizontal cracks traverse the entire wood pellet machine, cracks occur in the cross-section of the wood pellet machine, but the particles are not bent. This can happen when pelletizing fluffy wood chips that contain more fibers. Some customers cannot evenly dry the sawdust during the production process because of the selected type of dryer. Raw sawdust has uneven moisture content. After the ring dies compression granulation, due to the effect of moisture and the elasticity of the raw material itself, vertical cracks will occur.