Comparison Of Extrusion And Injection Molding Processes

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    China extruder machine has made great progress after years of development. Some domestic plastic machinery enterprises have seized the great opportunity in recent years and achieved leapfrog development, not only occupying a large domestic market share, but also a considerable number of products. Export to foreign countries.

    With the development of industrial technology and the improvement of people’s living standards, people’s requirements for the type and quality of plastic products are increasing. In-depth study of Film Extrusion Line molding equipment and its related control technology, so as to overcome defects in products and improve product quality, is of great significance for the improvement of injection molding technology. Among the plastic molding equipment, china extruder machine and injection molding equipment are the most widely used. Therefore, this paper introduces the control technology of these two equipment in detail.

    Comparison Of Extrusion And Injection Molding Processes

    Concept comparison


    china extruder machine extrusion molding is also called extrusion molding in plastic processing. In non-rubber extruder processing, the hydraulic press is used to press the mold itself to extrude it. It refers to a processing method in which the material passes through the action between the extruder barrel and the screw, is heated and plasticized, and is pushed forward by the screw, and continuously passes through the head to make various cross-sectional products or semi-products.

    Injection molding:

    The injection molding machine uses the properties of plastic to be melted into a liquid after heating to a certain temperature. The molten liquid is injected into a closed mold cavity with high pressure. After cooling and shaping, the mold is ejected to obtain the desired plastic product.

    Raw material comparison

    1. The difference in liquidity

    Injection molding requires high fluidity, especially for thin-walled products and large-scale products. Extrusion is a little looser on the requirements, because the extrusion is open and there is no huge resistance to the reverse of the die.

    2. Melt strength

    Injection molding is formed in a mold, and there are geometric limitations of the mold composition, which does not require high melt strength. Although extrusion molding also has geometric limitations of the die, it is not fully solidified after exiting the die. In this free state, sometimes due to low melt strength, it cannot be formed well (such as spinning).

    After china extruder machine is extruded, it is often accompanied by subsequent processing and molding in free state, such as thermoforming and hollow blow molding. During these molding processes, there are often different degrees of melt stretching. If the melt strength is low, it is easy to Pull out. So injection molding generally does not require high melt strength, while extrusion is generally required.

    3. Export expansion

    Injection molding generally does not have strict requirements on outlet expansion, and extrusion outlet expansion can cause great problems. Therefore, the viscoelasticity control of injection and extrusion materials will also be different.

    4. Applicable raw materials


    Most thermoplastics and some thermosetting plastics, such as PVC, PS, ABS, PC, PE, PP, PA, acrylic resin, epoxy resin and melamine resin, etc.


    With the exception of very few thermoplastics, almost all thermoplastics can be formed by this method. Injection molding can also process some thermosetting plastics, such as phenolic plastics.

    china extruder machine

    Feature comparison

    1. Extrusion

    • The production process is continuous, plastic parts of any length can be extruded, and the production efficiency is high.
    • The mold structure is also relatively simple, the manufacturing and maintenance are convenient, the investment is small, and the effect is fast.
    • The internal organization of the plastic parts is balanced and compact, and the dimensions are relatively stable and accurate.
    • Strong adaptability, except fluoroplastics, all thermoplastics can be extruded, and some thermosetting plastics can also be extruded. By changing the die of the die, the cross-sectional shape and size of the product can be changed accordingly, so that various plastic parts of different specifications can be produced.
    • Wide application range, simple operation equipment, low investment, quick effect, hygienic production environment, low labor intensity, suitable for mass production.

    2. Injection molding

    • Can be injection molded plastic products with complex shapes.
    • The product structure and size are more accurate and the surface quality is better.
    • Injection products can be standardized, standardized and serialized.
    • The operation is relatively simple, the molding die is easy to adjust and update, and it can be fully automated with high production efficiency.
    • The investment of injection molding equipment is relatively large, the cost of mold manufacturing is high, and the molding process conditions of products need to be strictly controlled.
    • Short production cycle and high production efficiency.

    Application comparison

    1. Application of china extruder machine extrusion molding

    china extruder machine extrusion is used in the processing of thermoplastics and rubber. It can be used for batching, granulation, rubber filtration, etc. It can be continuously produced to manufacture various continuous products such as pipes, profiles, plates (or sheets), films, etc. ,high productivity.

    2. Application of injection molding

    Injection molding is a method of producing shapes for industrial products. Injection molding can also be divided into injection molding and die casting. Injection molding machine (referred to as injection machine or injection molding machine) is the main molding equipment for making thermoplastic or thermosetting materials into various shapes of plastic products using plastic molding molds. Injection molding is achieved by injection molding machines and molds.

    • Plastic injection molding

    Plastic injection molding is a method of plastic products. The molten plastic is injected into the mold of plastic products by pressure, and the desired plastic parts are obtained by cooling and molding. There are mechanical injection molding machines dedicated to performing injection molding. The most commonly used plastic today is polystyrene.

    The resulting shape is often the final product and no further processing is required before installation or use as a final product. Many details, such as bosses, ribs, and threads, can be formed in a single injection molding operation.

    • Rubber injection molding

    Rubber injection molding is a production method in which the rubber compound is injected directly from the barrel into the mold for vulcanization. The advantages of rubber injection molding are: although it is an intermittent operation, the molding cycle is short, the production efficiency is high, the blank preparation process is cancelled, the labor intensity is small, and the product quality is excellent.

    China JWELL extruder machine Extrusion molding and injection molding are more common methods of plastic processing. Extrusion molding is mostly used in the processing of thermoplastics and rubber, while injection molding plastics and rubber can be used. It is the most commonly used thermoplastic. The processing method of thermosetting plastics is mostly injection molding. Judging from the molding process and molding equipment of the extruder, the extruder is not suitable for the processing of thermosetting plastics. It has its own advantages and disadvantages. Adding a new process can make it better.

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