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.
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.
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 injection molding services then he recommends you visit his friends at PTM: Innovative Plastic Solutions- Premium Plastic Solutions.