Introduction to Operating Temperature and Working Pressure Parameters of Sheet Extrusion Machines

The operating temperature and working pressure of sheet extrusion machines are critical parameters in the extrusion molding process, directly impacting product quality and production efficiency. Below is a detailed introduction to these two parameters:

I. Operating Temperature Parameters

The operating temperature of sheet extrusion machines primarily involves several aspects, including barrel temperature, die temperature, and cooling temperature.

Barrel Temperature: The barrel temperature is one of the main sources of plastic melt temperature. It depends on the type of plastic and the design of the extrusion machine. Different types of plastics have different melting temperature ranges, so the barrel temperature needs to be set according to the characteristics of the plastic. For example, for PC materials, a drying temperature of 65°C is maintained during the preheating stage, followed by a continuous increase in temperature to the molten state. In the extrusion molding process of acrylic materials, the temperature range of the rear part of the barrel is 150~230°C, the middle part is 180~220°C, and the front part is 180~200°C.

Die Temperature: The die temperature has a significant impact on the shape and dimensional stability of the extruded material. The die temperature is usually set based on the melting temperature and fluidity of the plastic. For example, the die temperature for PC materials is generally 140°C; while the die outlet temperature range for acrylic materials is 180~230°C.

Cooling Temperature: Cooling temperature refers to the temperature when the extruded material leaves the die and is cooled by a cooling device (such as a cooling wheel). The control of cooling temperature is crucial for the dimensional stability and surface quality of the product. For example, on a PC sheet extrusion production line, the roller temperature needs to be preheated to 80~110°C (depending on the product molding requirements).

II. Working Pressure Parameters

The working pressure of sheet extrusion machines primarily involves two aspects: extrusion pressure and die head pressure.

Extrusion Pressure: Extrusion pressure refers to the pressure that the plastic is subjected to during the extrusion process. It depends on factors such as the fluidity of the plastic, the structure of the barrel and die, and the rotational speed of the screw. The magnitude of extrusion pressure affects the quality and yield of the extruded material. For example, the extrusion pressure range for acrylic materials is 2.8~12.4 MPa.

Die Head Pressure: Die head pressure refers to the pressure when the extruded material leaves the die. It has a significant impact on the stability and density of the extruded material. Increasing die head pressure can improve the mixing uniformity and stability of the extruded melt, but excessively high die head pressure can affect yield. For example, in the production of polystyrene foam sheets, the pressure at the outlet of the first extruder is generally controlled at 1015 MPa, and the pressure at the die head of the second extruder is generally 1018 MPa, but it should not exceed 20 MPa.

In summary, the operating temperature and working pressure parameters of sheet extrusion machines need to be set according to the type of plastic, the design of the extrusion machine, and the requirements of the product. Reasonable temperature and pressure parameters can ensure the smooth progress of the extrusion process, improving product quality and production efficiency.

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