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Extrusion Process Conditions for Rubber Extruders

Time：

2018-12-29

When operating a rubber extruder, the key factors to monitor are temperature and speed. Proper temperature control ensures smooth extrusion, increases production output, and enhances the quality of the extrudate—resulting in a smooth surface, dimensional stability, precise dimensions, and a low expansion ratio. If the extrusion temperature is too low, the extrudate may exhibit a rough surface, an enlarged cross-section, and increased electrical load; conversely, excessively high temperatures can lead to scorching and foaming. Therefore, an appropriate temperature profile must be employed throughout the extrusion process. Typically, different sections of the extruder should maintain distinct temperature settings: the barrel is usually set at a lower temperature, while the die head operates at a higher temperature; moreover, the barrel itself may be divided into one or more zones.

When operating a rubber extruder, the primary factors to monitor are temperature and speed. Proper temperature control ensures smooth extrusion, boosts production output, and enhances the quality of the extrudate—resulting in a smooth surface, dimensional stability, precise dimensions, and a low expansion ratio. If the extrusion temperature is too low, the extrudate may exhibit a rough surface, increased cross‑sectional dimensions, and higher electrical load; conversely, excessively high temperatures can lead to scorching and foaming. Therefore, an appropriate temperature profile must be employed throughout the extrusion process. Typically, different sections of the extruder require distinct temperature settings: the barrel is set at a lower temperature, while the die head operates at a higher temperature. The barrel itself may be divided into one or more temperature zones, with the screw temperature consistently maintained above that of the barrel.

The feeding section of a rubber extruder typically operates at a relatively low temperature, which facilitates feeding and enhances extrusion uniformity. For most rubber compounds, a temperature setting of 43–60°C is sufficient; for harder compounds, the temperature can be slightly increased to 49–60°C.

High temperatures at the die and die‑land of a rubber extruder offer two advantages: first, they can reduce the swell ratio of the extrudate; second, they can lower die pressure, thereby helping to increase extrusion output.

A lower barrel temperature in an extruder can increase the viscosity of the rubber compound. Therefore, in practical operation, maintaining a barrel temperature lower than the screw temperature is beneficial for boosting production output. However, the temperature differential between the extruder barrel and the screw must be kept within an appropriate range. If the temperature difference is too large, although it may enhance throughput, it can degrade the quality of the extrudate, leading to defects such as micro‑porosity and spiral marks; conversely, if the temperature difference is too small, production output will decline.