Differences between Blow Molding and Injection Molding

15 November, 2023 by
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Molding Process

Blow Molding: It is a process where high-pressure air is used to blow plastic raw material into hollow products.
Injection Molding: It involves injecting plastic raw material into a mold, allowing it to cool and solidify to form the product.

Material Selection

Due to the differences in the molding processes, the characteristics and performance requirements of the plastic materials used are also different.
Blow Molding requires thermoplastic materials with certain expandability and plasticity. Injection Molding requires plastic materials with good flowability and melt stability.

Application Areas

Blow Molding: It is primarily used for manufacturing hollow products such as plastic bottles, containers, and toys. Since these products require internal space, blow molding is the most suitable method.
Injection Molding: It is suitable for various shapes and sizes of plastic products, including parts, casings, accessories, toys, and household appliances. Injection molding offers greater flexibility and can produce a wider range of products.

Blow Molding Production Process

  1. Material Inputting:
    Depending on the machine type, plastic is inputted and heated through a screw.
  2. Plasticization and Extrusion:
    The plastic is heated to a temperature within the plasticity range. The machine extrudes the plastic into a parison and closes the mold, covering the parison.
  3. Blow Molding:
    High-pressure air is injected into the parison, causing it to inflate and cling to the mold's interior, forming its shape.
  4. Mold Release after Cooling:
    After the plastic has cooled, the mold can be opened, and the finished product can be removed.

Injection Molding Production Process

  1. Plasticization:
    The plastic raw material is heated to a high temperature inside the barrel, melting it into a molten state.
  2. Injection:
    Using a screw, the molten plastic material is injected into the mold.
  3. Holding Pressure:
    After the plastic raw materials are filled into the mold, continue to pressurize the space in the mold.
  4. Mold Release after Cooling:
    The product is rapidly cooled and solidified within the mold. The mold can be opened, and the molded product can be removed.

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