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Clearance between screw and barrel

Por Cathy Lin September 27th, 2024 vistas 8
‌‌ The definition and importance of clearance between screw and ‌ barrel ‌‌

Screw and barrel clearance refers to the space distance between the screw and the inner wall of the barrel. This clearance has an important effect on the performance of ‌ extruder. The size of the gap is directly related to the output of the extruder, the plasticizing effect and the energy consumption. Reasonable clearance design can reduce leakage flow, improve extrusion efficiency, reduce the wear of screw and barrel, and extend the life of equipment.

‌ Influence of clearance on working performance of extruder ‌

The size of the clearance between screw and barrel directly affects the leakage rate of extruder. Leakage rate refers to the flow of melt in the gap between screw and barrel, which directly affects the output of extruder. The leakage flow is proportional to the cubic of the gap between the screw and the barrel, so reducing the gap can effectively reduce the leakage flow and increase the output. In addition, the gap also affects the heat transfer and shear rate of the melt, which affects the melting effect of the material.

‌ The selection principle and influencing factors of gap ‌

The selection of the gap between the screw and the barrel needs to consider a number of factors, including the nature of the material to be processed, the resistance of the head, the material of the screw barrel and its heat treatment, the machining conditions and the diameter of the screw of the injection molding machine. In general, the larger the diameter of the screw, the larger the clearance should be selected; Conversely, the smaller the diameter of the screw, the smaller the gap should be selected. In addition, heat-sensitive materials require a smaller gap to reduce heat loss, while non-heat-sensitive materials can appropriately increase the gap.

‌ gap adjustment and maintenance methods ‌

In the actual use process, the adjustment and maintenance of the clearance between the screw and the barrel is the key to ensure the stable performance of the extruder. Common adjustment methods include regularly checking and adjusting the mating accuracy of the screw and the barrel to ensure that the concentricity and perpendicularity meet the requirements. In addition, it is also necessary to regularly clean the barrel and screw to prevent clearance changes caused by carbon accumulation or impurities.
Important parameters of barrel screw
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Important parameters of barrel screw
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Screw and barrel matching requirements
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