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Plastic Molding: Why It’s Still The King in Manufacturing

Plastic Molding: Why It’s Still The King in Manufacturing
February 8, 2018 sdcdesign
Plastic molding machine with blow molded bottles

Plastic Molding: Why It’s Still The King in Manufacturing


Plastic molding is the most important process in modern manufacturing for creating high-quality, durable plastic products. Because the items made through plastic molding are both strong and cost-efficient, it’s worth understanding the specific processes that fall under that umbrella term.



In extrusion, a chamber (the extruder) is fed with plastic beads, pellets, and powder. A long metal screw within the extruder constantly churns, liquefying the plastic through mechanical friction. The chamber then forms the plastic into the desired final product, after which it is transferred to a conveyor belt and cooled with water. Then any rough edges on the plastic are trimmed or sanded, and the finishing touches are put on the item. This process is most commonly used in the production of simple plastic items such as pipes and sheets, products without a large variety of angles and ridges.


Injection Molding

Injection molding involves a hopper, a chamber where liquid plastic is pooled (it can be poured in as liquid or liquefied here via an outside heat source). From here, the plastic is forced into a metal mold under intense pressure until the mold is filled with no air bubbles remaining in the plastic. Once this is complete, the item is allowed to cool before being removed from the mold, cleaned, and finished. This method is best for solid plastic items that are more complex in shape than pipes or flat sheets—toys, plastic silverware, and car parts are examples of products best made with injection molding.


Blow Molding

The blow molding process for manufacturing is similar to injection molding in that it uses liquid plastic and a metal mold. The difference is that blow molding is designed to create hollow objects such as water bottles. Rather than being forced directly into the mold, the plastic is poured into a plastic tube called a parison. The parison is sealed at each end, a blow tube is inserted, and air is forced into the plastic so that it expands and takes the shape of the mold. Once this is complete, the item is removed, and excess plastic pieces (‘flash‘) from the ends of the parison are cut off to create the finished product.



Using these three processes, plastic can be formed into nearly any object a person might need to use. If your company needs molded plastic products made in the USA, Valencia Plastics is here to help.  Contact us for more details on making high-quality, cost-efficient goods.





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