There are numerous procedures that go into manufacturing various goods. Blow molding is among those and is meant to produce hollow parts using plastic materials. Generally, there are three kinds done in this process: injection stretch, injection, extrusion.
This practice begins with melting plastic. This is then formed into a preform or parison. The former is used for injection and injection stretch procedures. Parison refers to plastic in a tube shape that includes a hole at the end for compressed air to pass through. This is clamped to the mold and the air is blown inside. Pressure from said air is strong enough to push plastic to fit the mold. After it has cooled and hardened, the mold opens and is ejected.
William Kopitke and Enoch Ferngren are credited as the first to have used this process. The concept behind the technique is nothing new and is based off glassblowing. The two men built a blow-molding device and in the later half of the 1930s, sold it to the Hartford Empire Company. This move would lead to the eventual popularity of the process commercially.
Because of the limitations of number and variety in products, this practice did not become more popular until later. Once the production rates and variety increased, so did the number of goods created. In the US soft-drink industry, the amount of plastic bottles made went from zero during the late 1970s to approximately ten billion in 1999. Nowadays, even more of these products are blown and the number is only expected to increase more.
There are multiple typologies with this practice. Extrusion process, also known as EBM, involves the plastic being melted and later extruded in a tube that is hollowed out. The process might be intermittent or continuous. The kinds of products typically made with this approach: watering cans, automotive ducting, milk bottles, polyethylene hollow products, shampoo bottles and more.
The injection process, also referred to as IBM, is used in production of plastic goods in bulk and hollow glass. During this procedure, polymer is directly injection molded onto core pins. The pins are rotated to a station for the steps of inflation and cooling. The process is actually the least common of the three types. When it comes to injection stretch, the main techniques: single and two-stage processes.
All three kinds of this molding have disadvantages and advantages. Additionally, these are each used for the manufacture of varying products. This practice, overall, is very common today and seen in many industries.
This practice begins with melting plastic. This is then formed into a preform or parison. The former is used for injection and injection stretch procedures. Parison refers to plastic in a tube shape that includes a hole at the end for compressed air to pass through. This is clamped to the mold and the air is blown inside. Pressure from said air is strong enough to push plastic to fit the mold. After it has cooled and hardened, the mold opens and is ejected.
William Kopitke and Enoch Ferngren are credited as the first to have used this process. The concept behind the technique is nothing new and is based off glassblowing. The two men built a blow-molding device and in the later half of the 1930s, sold it to the Hartford Empire Company. This move would lead to the eventual popularity of the process commercially.
Because of the limitations of number and variety in products, this practice did not become more popular until later. Once the production rates and variety increased, so did the number of goods created. In the US soft-drink industry, the amount of plastic bottles made went from zero during the late 1970s to approximately ten billion in 1999. Nowadays, even more of these products are blown and the number is only expected to increase more.
There are multiple typologies with this practice. Extrusion process, also known as EBM, involves the plastic being melted and later extruded in a tube that is hollowed out. The process might be intermittent or continuous. The kinds of products typically made with this approach: watering cans, automotive ducting, milk bottles, polyethylene hollow products, shampoo bottles and more.
The injection process, also referred to as IBM, is used in production of plastic goods in bulk and hollow glass. During this procedure, polymer is directly injection molded onto core pins. The pins are rotated to a station for the steps of inflation and cooling. The process is actually the least common of the three types. When it comes to injection stretch, the main techniques: single and two-stage processes.
All three kinds of this molding have disadvantages and advantages. Additionally, these are each used for the manufacture of varying products. This practice, overall, is very common today and seen in many industries.
About the Author:
Henry A. Parker has taught plastics molding techniques for over 15 years. He specializes in injection molding and thermoforming. If you are interested in learning more about premium plastic solutions then he recommends you visit his friends at PTM: Plastic Injection Molding Services.
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