The Versatility of Extrusion Processes

Extrusion, an essential process in modern industries, is widely applied to the forming of various materials. Examples include aluminum extrusion (metal extrusion) for products such as aluminum window frames and automotive part casings; food extrusion for items like pasta and candies; ceramic extrusion for manufacturing ceramic filter cores used in filtration systems; rubber extrusion for products like seals and rubber tubes; and plastic extrusion for items like sheets (films) and plastic pipes.

Extrusion processes are heavily utilized in plastic molding and, along with injection molding, represent the two primary methods of plastic forming. In extrusion, plastic pellets are heated and softened through an extruder mechanism, transforming them into a pliable liquid state. This material is then subjected to high pressure and forced into a mold or die, creating objects with specific cross-sectional shapes. This process offers high production efficiency and remarkable flexibility. The critical component in extrusion molding is the "extrusion die."

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What is an "Extrusion Die"? What are its Types?

Based on the shape and application of the mold, extrusion dies can be categorized into the following types:

1. Aluminum Extrusion Die

    Aluminum alloy is currently one of the most widely used metals in the industry. Therefore, this type of die is specifically designed for manufacturing aluminum and alloy parts.

    Applications include the aerospace, automotive, marine, construction, motor housing, and mechanical framework industries.

 Aluminum extrusion dies are primarily used to produce aluminum alloy components, widely applied in construction and structural frameworks.

Die casting dies are similar to aluminum extrusion dies but are used for forming a wider range of metal materials, such as zinc, magnesium, and copper alloys. These dies are commonly applied in the production of gears, automotive interior components, valves, and other mechanical parts.

The difference between die casting dies and aluminum extrusion dies lies in their application scope. Die casting dies handle a wider variety of metal materials and are used to produce many types of mechanical components.

2. Profile Extrusion Dies

Profile extrusion dies are mostly used for producing various types and sizes of pipes, such as plastic pipes and hoses. They are also used to manufacture construction materials like plastic door frames, wood-plastic flooring, and roofing materials.

A similar type of die is the hollow profile extrusion die, which may refer to aluminum extrusion dies designed for producing hollow aluminum alloy products. It can also refer to profile extrusion for creating plastic window frames, wood-plastic flooring, or hollow plastic sheets (also known as corrugated sheets). For easier distinction, the latter is often referred to as "hollow flat sheets."

(Left) Profile Extrusion Dies are specifically designed for producing pipes. (Center) Hollow Profile Extrusion Dies are used for manufacturing metal or plastic frames.(Right) Another type of hollow die, also known as a hollow flat sheet extrusion die, is used for producing hollow plastic sheets.

3. Multi-Layer Coextrusion Dies

Products made from multi-layered plastics can be produced through different processes, using two types of multi-layer film dies: blown film dies and flat multi-layer dies (also called multi manifold die). The differences between these two are as follows:

(Left) Blown Film Die: Primarily used for producing various flexible packaging materials, such as plastic bags. (Right) Flat Multi-Layer Die: Used for producing high-precision optical films.

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4. Flat Extrusion Die 

Flat extrusion dies are composed of two or more flat steel plates joined together. Due to the internal flow channel design often resembling a T-shape, they are sometimes referred to as T-dies. However, in practice, as plastic materials evolve rapidly, the flow channel design has expanded beyond the single T-shape to include structures such as coat-hanger shapes, fishtail designs, and multiple cavity designs to ensure uniform plastic flow within the die cavity.

The die structure can also be tailored to practical requirements and may incorporate automated control systems, width adjustment systems, and thickness adjustment systems. These dies are widely used in production lines for sheets, films, lamination, hollow sheet, foaming materials, and filament extrusion.

 Flat extrusion dies, to meet diverse applications, can be equipped with systems such as automatic control, width adjustment, and thickness adjustment.

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Flat extrusion dies, due to varying application fields, have evolved into meltblown and spunbond dies. The former is used for producing meltblown fabric (also known as nonwoven fabric), commonly applied in mask filter layers and filter cores. Additionally, coating dies—another derivative—are utilized in critical coating processes for new energy industries (such as solar energy, energy storage batteries, and lithium batteries), semiconductors, and medical products. These dies are characterized by extremely small slit openings and are often referred to as slot dies.

Extrusion dies, due to varying application fields, have evolved into coating dies (left, also known as slot dies) and meltblown dies (right).

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