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How to Tell a Product was Made by Plastic Injection Molding

Believe it or not, many of the items around you in your day-to-day life are created through a process called plastic injection molding, but how can you tell which ones they are?

Once you know what to look for its easy to see!

Due to the way plastic injection products are created, there are often small identifiable marks left on them that point to their creation method. Often, these marks will be caused by feed points or ejection points. So, what do these marks look like? A feed point looks like a dimpled circle and an ejection point looks like a circle. Take for example this picture of plastic water bottles.

While the bottles themselves may have been created by plastic injection molding or blow molding, the caps were most definitely made through plastic injection molding. See the telltale dot in the centre of the cap? That's evidence of an ejection point. The larger circle surrounding the dot could be a design choice, or it could have been caused by a feed point.

So why are there always telltale marks on plastic injection molded products? Well, it has to do with the way in which the melted plastic is pushed into and out of the mold and the way the mold is designed.

If you look at plastic cutlery, you'll notice that there is usually a sharper edge along the sides of the utensils. This sign of injection molding can be caused by the parting lines Mold halves are never perfectly aligned and do not have sharp corners. This creates a natural parting line in the plastic.

When injected plastic has cooled in a mold it then needs to be pushed out of the mold. This is done using ejector pins. Just like on the water bottle lids above, this pushing motion with the ejector pins leaves a circular mark. Something similar can be said for the feed point marks, these marks are formed when the screw has injected all the plastic into the mold. The tip of the screw leaves a little circular divot.

Look around, now that you know the telltale signs of plastic injection molded products, we're sure you'll see them all around you! If you're looking to get plastic injection molds to create plastic products, just visit our contact us page!


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