Plastic containers are used for everything today. The process of how plastic containers are created today is known as blow molding and originated in December 1942. The use of plastic bottles has continually increased, but plastic blow molding has stayed fundamentally the same.
Why was Blow Molding First Developed?
Blow molding was first developed to produce celluloid baby rattles, but this turned into the beginning of the plastic bottle industry. From plastic baby rattles, the industry began to manufacture hollow plastic parts and then plastic bottles.
Plastic Blow Molding Rapidly Went High Tech
The technique of blow molding has developed into an extremely high-tech industry that dominates the manufacturing of plastic bottles. The format allows each bottle to be uniform in thickness, and an infinite number of outside body shapes can be produced.
The Basic Process of Plastic Blow Molding
There are four methods of blow molding that are commonly used in the plastic industry: Injection, Stretch, Extrusion and Reheating.
- The resin used is thermoplastic, and is heated until to a liquefied state.
- It is then forced through a die head to form a parison or a hollow tube.
- The parison is then dropped into a mold with two halves while it is liquid.
- Then the two halves close around it, and the parison is inflated.
- As the polyethylene is cooled, it turns from liquid to a solid.
- The mold is opened, and a solid, plastic bottle is removed.
Today, blow molding is the most common method of making polyethylene bottles. Plastics are a huge industry, and in the U.S. alone over 40 billion plastic bottles are produced every year.