There are many different processes involved with manufacturing. Blow molding is the term used to describe one of those processes in which hollow parts made of plastic are formed. Generally speaking, there are three kinds of this: extrusion, injection and injection stretch.
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 different typologies when it comes to this practice. EBM, or the extrusion process, involves plastic being melted and then extruded into a hollow tube. These processes might be continuous or intermittent. Types of products made from this practice: milk bottles, automotive ducting, shampoo bottles, watering cans, polyethylene hollow products and more.
Injection, or IBM, is employed for production of hollow glass, as well as plastic objects in big quantities. With this process, polymer is injection molded on a core pin, which is rotated to another station to be inflated and later cooled. This is the least used process of the three different kinds. There are two different methods commonly used for the injection stretch process: single and two stage.
Advantages and disadvantages come with each of these different processes. Furthermore, they might be utilized for the making of different goods. The practice itself has become more popular and is used in many different industries in operation today.
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 different typologies when it comes to this practice. EBM, or the extrusion process, involves plastic being melted and then extruded into a hollow tube. These processes might be continuous or intermittent. Types of products made from this practice: milk bottles, automotive ducting, shampoo bottles, watering cans, polyethylene hollow products and more.
Injection, or IBM, is employed for production of hollow glass, as well as plastic objects in big quantities. With this process, polymer is injection molded on a core pin, which is rotated to another station to be inflated and later cooled. This is the least used process of the three different kinds. There are two different methods commonly used for the injection stretch process: single and two stage.
Advantages and disadvantages come with each of these different processes. Furthermore, they might be utilized for the making of different goods. The practice itself has become more popular and is used in many different industries in operation today.
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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