Abnormal moisture content in raw materials is one of the most common causes of extruder shutdowns. For a single-screw pet food extrusion machine to function properly, the moisture content of the raw materials needs to be controlled between 12% and 15%. This range ensures sufficient frictional heat generation within the extrusion chamber while preventing clumping and blockage. If the moisture content is too high (above 15%), the raw materials will clump together within the extrusion chamber, hindering smooth feed and gradually clogging the feed inlet and extrusion chamber. This causes a sharp increase in the extruder load, triggering the overload protection device and ultimately shutting down the machine. For example, when making homemade fish feed, if raw materials such as corn flour and soybean meal are not fully dried and have excessive moisture, they are prone to clogging and shutdown after being fed into a mini extruder. Conversely, if the moisture content is too low (below 12%), the friction between the raw materials and the screw and extrusion chamber walls will be insufficient, failing to generate stable extrusion pressure. Furthermore, excessive material flowability may lead to uneven feeding, which can also cause the equipment to shut down due to unstable load.
Inappropriate particle size or excessive impurities in the raw materials can also cause the twin-screw fish feed extruder machine to shut down. Extruders require raw materials to be ground to a particle size of 60-100 mesh. If the raw material particles are too large, or if incompletely ground lumps or impurities are mixed in, these large particles can become stuck between the screw and the extrusion chamber, or clog the die orifice, hindering the material's feed and causing a sudden increase in the extruder's load, thus triggering a shutdown protection mechanism. This is especially true when processing low-cost raw materials such as cottonseed cake and grass meal; if these materials are not rigorously screened, the impurity content will be even higher, significantly increasing the risk of shutdown. Furthermore, the presence of hard impurities such as metal shavings and stones in the raw material can not only cause shutdowns but also severely damage the extruder's screw, die, and other core components, resulting in even greater losses.
For downtime caused by raw material issues, the following solutions can be adopted: First, strictly control the moisture content of the raw materials. Before production, use a moisture meter to test the moisture content. If the moisture content is too high, sun-dry or oven-dry the materials; if the moisture content is too low, spray a small amount of warm water to adjust. Second, optimize the raw material pretreatment process to ensure that the raw material particle size meets the standards. Thoroughly screen impurities using a vibrating screen to prevent large particles and hard impurities from entering the equipment. Finally, if a blockage has already occurred, immediately disconnect the power for cooling, disassemble the extruder's feed hopper and die, use specialized tools to clean the blocked raw materials and impurities, and check the screw and extrusion chamber for damage. Restart the equipment only after confirming there are no problems. Establishing a raw material pretreatment inspection mechanism in daily production can reduce such downtime failures at the source.
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