During wood pellet production, wood pellet machines occasionally discharge a significant amount of powdered raw material along with the pellets. In severe cases, it can appear as though raw materials are leaking directly from the die holes, presenting a serious operational challenge. This issue not only compromises the quality and market value of fuel pellets but also reduces the output efficiency of the wood pellet making machine. Let’s examine the underlying causes of why the wood pellet machine may produce excessive powder instead of forming pellets and explore the appropriate solutions
No.1 The moisture content of the raw materials is too low, resulting in overly dry material.
The optimal moisture content for raw materials used in wood chip pellet machine is typically between 13% and 18%, with 15% being ideal. Excess powder in the pellets often indicates that the raw materials are too dry, with insufficient moisture content, making extrusion and pellet formation challenging and leading to excessive powder. Conversely, if the moisture content is too high, powder levels may decrease; however, the wood pellets produced will be low in hardness and density, and the ring die may become blocked, preventing normal operation of the wood pellet making machine. If excessive powder is due to low moisture content, simply adjust the moisture level of the raw materials. This can be achieved by maintaining moisture content within the 13% to 18% range, either by mixing dry and wet sawdust or by lightly spraying water mist
No.2 The fiber content in the raw material is too low for the wood pellet mill.
When the fiber content in the raw material is too low or the material consists primarily of fine powder, pellet formation becomes difficult. Excessively fine particles or high powder content can prevent proper pellet formation, especially if the material comes from MDF processing, where the particles are often very fine. In such cases, increasing the moisture content or using a flat die pellet machine can improve results. For ring die pellet machines, it is generally necessary to adjust the composition of raw materials, such as blending with other wood chips in suitable proportions before pelleting. This approach effectively reduces powder generation and supports optimal pellet formation.
No.3 The compression ratio of the biomass pellet machine ring dies is too low.
The compression ratio of the wood pellet machine ring die may be improperly configured, or the pressure may be set too low. Different raw materials—such as hardwood, softwood, straw, and rice husks—require specific compression ratios for optimal pellet formation. If the compression ratio is too low, insufficient pressure will result in loose pellets with weak bonding, making them prone to breaking into powder. Additionally, if the pellet mill die internal finish is rough, the pellet machine die holes are not smooth or vertical, the inlet slope angle is too shallow, or the ring die of the pellet machine is out of round, these issues can prevent pellets from being properly formed. Conversely, if the compression ratio is too high, pellets may become overheated, blackened, or carbonized, and the machine may experience blockages. Choosing a professional wood pellet machine manufacturer is essential, as we can provide custom wear-resistant accessories tailored to specific raw material requirements. Therefore, if excessive powder in the pellets is due to an inappropriate pellet ring die compression ratio, this issue can be resolved by selecting the correct mold.
No.4 The pellet machine model or operating speed may be unsuitable.
Different raw materials and production schedules require specific biomass pellet machine types. For example, vertical ring die pellet machine are better suited for processing coarse fiber fuel pellets, while horizontal ring die pellet machines, with their higher speeds, are ideal for producing easily compressed feed pellets. Small flat die pellet machines with rotating molds are suitable for feed pellets only, whereas heavy-duty flat die machines with rotating press wheels can produce cattle and sheep feed pellets, fuel pellets, and fertilizer pellets. Choosing an appropriate machine model is essential for the stable and efficient operation
No.5 Significant wear on the wood pellet-making machine ring die or roller shell
Significant wear on the wood sawdust pellet making machine ring die or roller shell can impact the pellet quality. When internal components such as the roller shell and ring die are heavily worn, the die holes may flatten, their diameter may enlarge, and the extrusion force on the pellets becomes uneven. This reduces pressure during wood pellet formation, lowering the pellet forming rate and causing excess raw powder to mix with the pellets. If ring die or flat die wear is the issue, simply replacing the pellet machine roller shell and pellet machine die will resolve it. The pellet mill die and roller should be replaced every a few months based on the actual condition.
No.6 Damage of the pellet machine’s roller bearing or spindle bearing caused by a worn seal ring.
Damage to the roller bearing or spindle bearing can result from a worn seal ring in the wood pellet machine. When the seal ring is compromised, raw material dust can infiltrate the bearing chamber, leading over time to significant dust buildup in the spindle bearing chamber and causing bearing damage. To prevent this, it’s advisable to inspect the seal ring weekly for signs of wear or deformation and replace it immediately if any issues are detected.”
These are some effective methods for improving wood pellet quality in wood pellet machines during production. We hope you find them helpful. For your convenience, we’ve also created a simplified table below for quick reference. Please feel free to take a look!
| TROUBLE | SHOOTING |
| biomass pellet density too low | Change the ring die to a bigger press rate |
| biomass pellet density big and capacity low | Change the ring die to a smaller press rate or adjust the moisture content a little higher |
| The bearing life of the pellet machine roller is short | Please use high-quality bearings and high-quality lithium-based grease, and replace the oil seal regularly |
HOW TO MAINTAIN THE WOOD PELLET MACHINE
Routine wood chip pellet machine maintenance is essential to ensure optimal performance. Under normal operating conditions, we recommend a maintenance and inspection check every 1-2 weeks. Regular inspections can significantly extend the machine’s service life.
