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Believe it or not, if you think about our history, the industrial science of transforming plastic resins into useful things impacted our lives greatly. This is the polymer extrusion and how it creates products. This process began when it was designed in the 1930's and was the base of metal die casting designs and produces 100% American made products . Today the benefits of Injection molding include alternative methods toward manufacturing methods. Minimal losses of scrap pieces, since Injection Molding scraps can be melted and recycled. The difference between Injection Molding and metal casting molten metal's can be poured, plastic resins but be injected by force. Pretty interesting and unusual, I thought the same thing.

So all this talk about injection molding let's see the process beginning to start! The injection molding process uses large injection molding machines. They produce products from Halloween plastic decorations to computer parts. It's a very complex machine, but has only two basic elements.

The machine itself is quite simply made of two parts. Which are the Injection unit and the clamping unit. The parts of the machine are self explanatory in their actions. This is an interesting note, molten plastic cannot be poured like molten metal it must be injected.

This process begins with a mold, which is clamped under pressure to the injection and cooling process. The resins are fed into a machine and falls in to an injection barrel where they are heated to their melting point. Then screwed or rammed into the mold.

Next comes something called the dwelling phase. The dwelling phase is when molten plastic are within the mold and mechanically or by strength of hydraulics, forced down to fill all cavities of the mold. The plastic is the allowed to cool inside the mold.

As it opens injection pins help it escape the mold. It may not look perfect with items called runners all over the product. But those are simply shaved and recycled down for the next cycle. A cycle can last from anywhere from 10 to 100 seconds. Pretty interesting, a factor you would never think of.

That all depends on the cooling time and whatever the company's policy is. This is interesting; every type of resin has a shrinkage value that must be factored into the melting equation. If the equation is wrong the exterior shutters will be the wrong size or shape. Warpage is also a problem that needs to be avoided.

Temperature always needs to be monitored due to each different type of resin having a different shrinkage value. All temperatures must be factored. If not the product may be over size or shape and not be any use. When temps are too high it sets an uneven surface on the plastic. The mold may not be properly filled as a result from the temperature as well.