How Injection Molding Works

Assembling The Materials

First things first, we need some kind of initial material to construct the plastic with. Most companies find that using recycled or ground up plastic is not only easier, but also safer for the environment. The ground up plastic is referred to as polymer resin, or pellets. The pellets then must be fed into some kind of hopper. There are several types of hoppers, the two main types being covered and uncovered hoppers. Quite self-explanatory, the open hoppers are open and the closed hoppers are, well, closed.

Crushing The Pellets!

The next step in the injection molding process is converting the raw plastic pellets into a more usable form. This is typically accomplished by feeding the pellets into a barrel. An electric motor feeds the pellets up through the grooves of a device called an auger. The auger may contain a reciprocating screw to aid in the feeding process. These devices crush the plastic down so it’s easier to be liquefied.

Increasing The Temperature!

Now this is probably the most fun step of them all. Melt the plastic! The melting temperature differs for the different types of plastic. High density polyethylene, for example has a melting temperature of 266 degrees Fahrenheit (130 Celsius)! That’ll give ya a gnarly burn!


This is where the magic really happens. The plastic is injected into a mold in some form. Now you see how it gets the namesake. Most modern-day plastic molds are made out of tough chromium-steel. These molds are massive! But also very precise… down to the nearest hundredth of a millimeter in fact. The next step in the process is the dwelling phase. This phase basically consists of looking at te mold and making sure that all the voids are filled. Failure to comply with this step could result in a distorted or incomplete finished product. The temperature is then brought back down so the liquefied plastic can harden again.

As always there pros and cons with this process. Most companies like the fact that there is an ability to keep up with high levels of production. This process allows for quite a bit of detail and can also be done in a relatively short amount of time. However, this process is ideal only for larger companies with capital behind them, as the machines and molds can be quite expensive. But if you have the ability to do so, the pros definitely outweigh any other cons.

Enjoy The Finished Product!

And there you have it. So next time you see a plastic product, think of all of the work that went into making it!

Post time: 05-14-2017