Mold Tech

Analysis of Plastic Extrusion Die Design

• 2024-09-19

The market for plastic products is expanding, with a growing variety of extruded products such as pipes, sheets, films, and profiles playing a significant role in various applications. The extrusion process involves heating and melting raw materials before shaping them through extrusion and then cooling and solidifying the material. This requires the extrusion equipment to have the functions of melting, shaping, and solidifying.

The quality of the extruded products depends largely on the quality of the molds and the uniformity of the molten material flow from the extruder to the molds. The shape of the extruded products can be altered by using special devices or operating methods, such as embossing or blow molding, especially for special cross-sectional shapes.

In recent years, there has been a development in co-extrusion methods where multiple plastics are extruded together, as well as co-extrusion with other materials such as aluminum, iron, and wood. This has led to increasing complexity in the structure of extrusion molds.

Mold design plays a crucial role in extrusion equipment, as it shapes the molten material supplied continuously at pressures up to 3MPa by the screw, into the desired cross-sectional shape of the extruded product. The flow path of the molten material within the mold needs to be designed to ensure smooth and unobstructed flow during the transition from the circular or rectangular entrance to the final extruded product.

The non-Newtonian flow characteristics of the molten material, with its viscosity and elasticity, must be considered when designing the mold. Factors such as pressure distribution, flow resistance, and shear stress need to be carefully analyzed to achieve high-quality extruded products.

The structure of the extrusion mold consists of four parts: material distribution, adjustment, buffer, and shaping. Each part plays a specific role in ensuring uniform pressure and stress distribution to achieve consistent and high-quality extruded products.

Temperature adjustment is also essential in extrusion mold design to maintain the mold temperature within a specified range. This is typically achieved by using heaters installed on the mold.

Analyzing and calculating the flow conditions of molten material in various cross-sectional shapes is crucial for ensuring the rationality of extrusion mold structure design.

Overall, the design and operation of extrusion molds require careful consideration of material flow characteristics, pressure distribution, temperature control, and stress uniformity to produce high-quality extruded products.

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