Different Methods of the Blow Molding Process


bottle blow molding machine

Manufacturing companies use different blow molding processes to make parts and components for their customers and in-house applications. Using thermoplastic material, this process creates both shaped and hollow products. While some blow molding manufacturers focus solely on the injection or extrusion process, most perform both services.

Regardless of the bottle blow molding machine, both manufacturing processes involve plastic, either as a melted polymer or a preform. They also produce stellar finished products. However, it’s how the machines perform that makes them unique.

Extrusion Blow Molding

The manufacturer begins by melting the specific type of polymer required inside a vat. There, a screw-style piston extrudes the material into a hollow tube referred to as a parison. Then, this blow molding equipment moves the polymer until it reaches a cold mold. In this case, the parison closes off so that only a certain amount of material passes through.

This mold serves as one of two purposes. First, it gives the material its shape as is. Second, a rod pushes air into the somewhat cooled material to create a hollow interior and expand it to create the shape of the product. For this bottle blow molding machine, the mold opens and ejects the product once it’s completely cool.

Now, there are a couple of variations that blow molding manufacturers offer specific to the extrusion process.

  • Continuous Extrusion Blow Molding – As the name implies, this means the machine runs constantly. As such, melted polymer continually flows through the different stages. That requires an operator to manually remove excess material from the part or component as it’s manufactured. Unfortunately, that leads to waste.
  • Intermittent Blow Molding – Using the same extrusion blow molding equipment, this has a rotating screw that only allows a certain amount of material through to get processed.

Injection Blow Molding

In this case, a preform gets blown into a PET container. Formally called polyethylene terephthalate, this material can vary in weight, shape, color, and even the finish of the neck. Manufacturers first make a preform based on a customer’s specifications. Then, they use the appropriate blow molding equipment to transform it into a viable product.

First, you would make an injection molded preform. That then travels through the bottle blow molding machine on a core rod until reaching the blow mold station. There, compressed air goes into the core rod, lifting the material off of it while producing the shape of the finished product.

Providing Customers with Superior Blow Molding Equipment

Whether your company utilizes an injection or extrusion bottle blow molding machine, you can rely on us for a superior product. At Pet All Manufacturing Inc., our entire staff dedicates itself to providing customers with the service they deserve. Give us a call to learn more.

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