If the surface of the extruded material is rough, there are bubbles or melt fractures, it may be necessary to increase the temperature near the feeding port area appropriately to promote better melting and plasticization of the material; If the shape of the extruded material is irregular and the size is unstable, it may be necessary to check whether the temperature of the machine head and the area near the machine head is appropriate, and fine adjustments may be needed to improve it; If the product exhibits casting, as mentioned earlier, focus on checking and adjusting the temperature of the machine head and nearby temperature zones; If there are cold spots or insufficient local plasticization in the product, it may be due to low rear end temperature, and the corresponding temperature zone needs to be appropriately raised; If there are signs of excessive burning or discoloration in the product, it may be due to certain temperature zones, especially those near the machine head, being too high and requiring appropriate reduction. At the same time, it is necessary to comprehensively judge and adjust factors such as material characteristics and screw speed.
So, how should we analyze the cause of extrusion when the extrusion machine produces casting?
Excessive temperature: The extrusion temperature is set too high, which leads to excessive melting of the material, excessive fluidity, and easy occurrence of casting phenomenon.
Excessive screw speed: This causes the material to extrude too quickly, making it difficult to form and cool, resulting in casting.
Unreasonable mold design: For example, excessive gap between the mold openings can cause excessive material flow and flow.
Material characteristics: Some materials have strong fluidity and may be more prone to flow under specific conditions.
Insufficient cooling: The cooling device is ineffective and cannot timely shape the extruded material, resulting in casting.
Excessive pressure: Excessive extrusion pressure may also cause excessive material extrusion and flow.
Where should we start to solve the problem of flow extension when it occurs?
Temperature adjustment: Carefully check the temperature of each heating zone, reduce the temperature appropriately, especially in areas related to casting, and find the appropriate temperature balance point.
Control screw speed: Reduce the screw speed to make the material extrusion speed moderate and avoid being too fast.
Optimize the mold: Conduct maintenance and adjustment on the mold, such as reducing the gap between the mold openings, to ensure that the mold design is reasonable.
Replace materials or adjust the formula: If the material itself has strong fluidity and is not suitable, consider replacing other materials or adjusting the material formula to improve its performance.
Enhance cooling effect: Check and maintain the cooling device, such as increasing cooling air volume, improving coolant circulation, etc., to ensure sufficient cooling.
Pressure adjustment: Reduce the extrusion pressure appropriately according to the actual situation to avoid excessive pressure causing flow elongation.
Cleaning impurities: Ensure that there are no impurities in the material to avoid affecting the extrusion molding.
Stable process parameters: Maintain the stability of other process parameters such as traction speed, and reduce the impact of fluctuations on extrusion.