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.
The process starts with the melting of plastic. Then it is formed in a parison or preform, which is used for injection stretch and injection procedures. The parison is a piece of plastic shaped like a tube that has a hole at one end in which the compressed air is able to pass through. This is then clamped to a mold and air is blown inside of it. The pressure from the air is enough to push the plastic out to match with the mold. Once it has cooled and hardened, the mold will open and the part can be ejected.
Two men are considered the first to have employed this practice: Enoch Ferngren and William Kopitke. These two also built a device for this practice and sold it to Hartford Empire Company in the year 1938. The concept of the process itself is based on that of glassblowing. The selling of the machine led to the commercial use of this practice.
There was limitations in number and variety of products that led to a slower popularity. As soon as the production and variety rates improved, the amount of goods increase as a reaction. In America’s soft-drink industry, plastic bottles being produced in 1977 were at zero. This number greatly increased to approximately ten billion by the year 1999. In the modern world, so many products are being made in this way and this number is expected to grow even 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.
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.
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 plastic pallets manufacturers then he recommends you visit his friends at PTM: Custom Plastics Injection Molding Company.
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What To Know About Blow Molding
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