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.
More than one typology is associated with the practice. EBM, or the extrusion process, relates to the plastic that is melted and then extruded in tubes that hollow it. The process might be considered continuous or intermittent. The types of goods produced through this method: automotive ducting, shampoo bottles, polyethylene hollow products, milk bottles, watering cans and more.
IBM, or the injection process, is used for producing hollow glass and plastic goods in large quantities. With this, the polymer is injection molded on core pins, which are then rotated onto a station for inflation and cooling. This is the process that is used the least in different types. There are two main techniques associated with injection stretch practice: two stage and single.
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.
More than one typology is associated with the practice. EBM, or the extrusion process, relates to the plastic that is melted and then extruded in tubes that hollow it. The process might be considered continuous or intermittent. The types of goods produced through this method: automotive ducting, shampoo bottles, polyethylene hollow products, milk bottles, watering cans and more.
IBM, or the injection process, is used for producing hollow glass and plastic goods in large quantities. With this, the polymer is injection molded on core pins, which are then rotated onto a station for inflation and cooling. This is the process that is used the least in different types. There are two main techniques associated with injection stretch practice: two stage and single.
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 injection moulding services then he recommends you visit his friends at PTM: Custom Plastics Injection Molding Company.
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