Analysis of factors affecting feed pellet forming rate
Home news-posts Analysis of factors affecting feed pellet forming rate
Abstract: Addressing the current issues of unstable pellet quality, poor pellet integrity, and severe wear of the main components, particularly the ring die, in pellet mills, along with the rapid development of the feed industry in China, which presents both opportunities and challenges, this paper analyzes the factors influencing the pellet formation rate based on the performance of pellet mills equipped with different ring die characteristics. This analysis is significant for optimizing the structure of pellet mills, improving the quality of feed pellets, reducing wear on critical components of the pellet mill, and lowering processing costs.
With the increase in livestock product consumption and the intensifying pressures of resource utilization and environmental protection, the feed industry faces new opportunities and challenges. In the coming period, the feed industry needs to fully extend the industrial chain and integrate resources to achieve significant development in the entire industry chain model. Simultaneously, feed processing machinery will enter a transformative development stage, shifting from quantity expansion to quality and efficiency improvement. This requires continuous enhancement of the operational efficiency of individual machines and the automation control level of complete equipment sets, improving equipment safety, reliability, ease of promotion, and reducing operational costs.
I. Factors Affecting Feed Pellet Quality
Feed processing involves major steps such as raw material reception, cleaning, crushing, batching, mixing, pelleting, cooling, crumbling, screening, and final product weighing and packaging, along with auxiliary processes like ventilation, dust removal, fat addition, and enzyme addition. Common raw materials include corn and bran, supplemented with soybean oil, phytase, vitamins, and trace elements. Typically, the moisture content of the prepared raw material is 12-15%. The quality of feed pellets is influenced by various factors, including the composition of feed ingredients, moisture content, particle size of the crushed material, pellet mill structure, conditioning effectiveness, and cooling results. Different raw material ratios result in varying bulk density, particle size, friction, and preservative qualities, leading to differences in starch content, fat content, protein, and fiber components, and consequently, variations in pellet stability and quality. Finer particle sizes increase the surface area of raw materials, allowing for uniform and rapid steam absorption, resulting in higher starch gelatinization and better pellet quality. Better conditioning prior to pelleting enhances starch gelatinization, improving adhesion and water resistance of the feed pellets.
II. Structure of the Ring Die Pellet Mill
The ring diepellet mill is the dominant model in the feed industry, widely used in large and medium-sized aquaculture farms, feed processing plants, and livestock and poultry farms. Its structure mainly consists of a feeder, conditioning chamber, pelleting chamber, and frame. The structural performance of the pellet mill significantly impacts feed pellet quality, involving factors like die structural characteristics, adjustment of the gap between the ring die and roller,ring die rotation speed or roller speed, number and diameter of rollers, and cutter structure.
During operation, the feeder continuously and uniformly transports powder to the mixing chamber and regulates the flow of powder. The conditioned powder then enters the pelleting chamber, where it is drawn into the working surface between the die and cylindrical roller by the action of the ring die and roller. The rotating die compresses the material into the compression zone, with the roller being passively rotated by friction between the ring die and the material, forcing the material through the die holes. Under intense compression, the material overcomes the resistance of the die walls and is continuously extruded from the die holes in strips.
III. The Impact of Ring Die Characteristics on Pellet Quality
The ring die, being the core component of feed pelleting operations, is also a primary wear part. The appropriate structural parameters of the ring die are directly related to the stability of the pellet mill, pellet quality, energy consumption, and processing costs. These parameters affect the service life of the ring die, the output and production efficiency of the pellet mill, and consequently, the overall processing cost. The ring die is a thin-walled, ring-shaped mold with many uniformly distributed small holes. Its main characteristics include the die hole shape, length-to-diameter ratio of the die holes, hole arrangement, open area ratio, working area, effective height, and wall thickness. Among these, the length-to-diameter ratio of the die holes, the height of the ring die, and the rotation speed of the ring die have a direct impact on the pelleting effect.
During the use of the pellet mill, different structural parameters of the ring die and varying rotation speeds are employed to observe and measure the feed pellet formation rate. Analysis reveals that the length-to-diameter ratio of the die holes has the greatest impact on the pellet formation rate, followed by the ring die rotation speed, while the height of the ring die has the least effect.
Length-to-Diameter Ratio of Die Holes: If the ratio is too small, the extrusion pressure on the raw material as it passes through the die holes is insufficient, resulting in loose pellets that are difficult to form. If the ratio is too large, it can cause material slippage, leading to blockages. In this case, the raw material undergoes greater extrusion pressure as it passes through the die holes, producing high-quality pellets. However, the more compact pellets are prone to breaking during cutting, thus reducing the formation rate. Additionally, a higher length-to-diameter ratio increases equipment energy consumption, accelerates ring die wear, and raises pelleting costs.
Ring Die Rotation Speed: The design of the rotation speed must be reasonable. Excessive speed reduces the pellet formation rate, while too low a speed hinders pellet formation, resulting in poor pellet quality.
Ring Die Height: This factor has a relatively small impact on the pellet formation rate. Generally, as the height of the ring die increases, the pellet formation rate improves. This is mainly because a higher ring die reduces the likelihood of powder spilling out from the top of the ring die before it is compressed into pellets. Therefore, within structural limits, increasing the effective height of the ring die can enhance the pellet formation rate, though attention must be paid to the increased processing cost of the ring die.
IV. Conclusion
This paper analyzes the factors influencing the pellet formation rate based on feed processing technology and the performance of commonly used ring die pellet mills. The findings have significant implications for optimizing the structure of pellet mills, improving the quality of feed pellets, reducing wear on critical components of the pellet mill, and lowering processing costs. By understanding these factors, the feed industry can achieve better efficiency and product quality, ensuring sustainable and cost-effective production practices.
