What is Blow Moldings and What’s it Good For?


Large plastic containers

What is blow molding, and who can use blow molded containers? Read on to find out more about how blow molding works, what types of blow molding there are, and who can use blow molded containers:

  • What is blow molding? Simply put, this is a way of manufacturing plastics that creates hollow plastic containers. The plastics industry in the United States currently employs about a million people, and the industry is adding $375 billion the economy every year. Plastics are in high demand because they are so useful, and the answer to the question “who can use blow molded containers” is “nearly anyone!” Only two pounds of plastic can make containers capable of holding 10 gallons of liquids like soda, medical supplies, or shampoo, to name just a few. It would take three pounds of aluminum to achieve the same result, or eight pounds of steel, or 40 pounds of glass! Blow molding allows us to make all kinds of custom plastic bottles.
  • What types of blow molding processes are there? Three of the big ones are injection blow molding, stretch molding, and extrusion molding. Injection blow molding makes plastic containers in large quantities by injecting a polymer onto a core pin, which is then inflated and cooled. This type of blow molding is used for small single-serve bottles, particularly for medical applications.
    The extrusion method first melts the plastic, which is then extruded into a hollow tube. The tube is then placed into a metal mold and cooled. The mold is then opened and the cooled plastic ejected. The stretch method involves molding the plastic into a preformed shape, which is then fed onto an extrusion machine. This method is typically used to make things like the necks of bottles, which can later be attached to the rest of the bottle from the extrusion blow molding machine.
  • Who can use blow molded containers? People in America are using 2.5 million plastic bottles every hour, and nearly all of them are made with the blow molding method. Every state in the country has injection molding facilities, and there are nearly 16,000 in total. Blow molded plastics are used for dairy products, shampoo, ductwork in cars, cleaning chemicals, and all kinds of drums. In fact, the vast majority of bottles, barrels, drums, and plastic containers are made using blow molding.


Blow molding was first used to make glass containers, but in the modern world, it is now used far more often with plastics. Whether you need customized plastic bottles or are just buying milk from the store, chances are you run into blow molded products all day, every day. Now you know how we get them!


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