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Plastic Injection or Blow Molding For Food Packaging?

November 30, 2015

Plastic packaging for food and beverage products comes in all shapes, sizes and colors.  But which standard plastic parts-forming process — blow-molding or plastic injection molding — is the right one for your product?

The answer is, of course, “it depends”.  On what, you ask? On a multitude of variables that include (but are not limited to) these parameters:

  • How big is your product, and its corresponding packaging?
  • How is it going to function?  (Will it need to bend, work with other parts, etc.)
  • Is its weight critical to how it works?
  • Will it need to withstand extreme heat or cold?
  • Will it hold solids or liquids?
  • Can it be flexible? Or does it have to be rigid?

Of course, answering these questions when designing and manufacturing any item is important. But if you’re talking about plastic food packaging, they are even more vital.  Because we haven’t even started to talk about types of plastic yet, which will also have an impact on whether you choose plastic injection molding or blow molding for your project.  As with most manufacturing processes, one millimeter size difference can make the product usable or unusable. So both accuracy and creative solutions are mandatory.

That said, there are many inherent advantages to plastic injection molding. Chief among them is that once your mold is completed (which, granted, can take a while), you are well on your way to mass production.  You inject the plastic, the mold does its molding thing, and you repeat until you either have as many as you need or the mold breaks — which could be years in the future.

Not so with blow-molding. There are many other concerns with this manufacturing process, such as:

  • pinholes
  • seal leaks
  • strength
  • velocity or pressure of blown air into the plastic bag
  • speed of the mold closing
  • temperature needed for manufacturing
  • wall thickness
  • consistent product sizes

If all of these concerns can be alleviated, then blow-molding might be a more cost-effective alternative than traditional plastic injection molding. But that’s a big “if”!




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