AIM Processing Small Plastic Parts Blog

In plastic injection molding, one of the most important aspects of the mold design is how and where it is gated. The “gate” is the opening in a mold through which the molten plastic is injected into the final part.  It is the boundary between part and scrap. The location, size, and shape of the gate can have a significant effect on everything from the structural integrity to the visual appearance of a finished piece.

Elastomeric overmolding (sometimes called “elastomer overmolding” or just “overmolding”) is a process in which a softer layer of material is bonded to a harder functional or structural component of a part. It can be used to improve functionality, to change the look of a part, or both. An example that most people are familiar with is a toothbrush handle with a soft, grippable section or covering. Other examples of overmolded parts include:

It would make sense that the thicker the walls of a part are, the stronger it is. However, that’s not always the case. That statement is based on the assumption that the walls have a uniform density. Unfortunately, thicker walls have the potential for voids or hollow spaces within them. This means you may not be getting the consistent depth, or the strength, you were counting on.

Insert molding, or more accurately “plastic injection insert molding,” is a process in which viscous plastic is injected into a mold around one or more items. When the plastic cools and hardens, the result is an integrated assembly that incorporates these “inserts.” The items can be metal, ceramic, or any other type of material that can withstand the heat of the melted plastic and the pressure with which it is injected into the mold.

Plastic injection molding is a very cost-effective way to produce high-quality parts. Even so, there are a number of things you can do to save even more money on a project without sacrificing anything in the finished product.

Structural foam molding is a process in which an inert gas is added to a melted polymer which is then injected into the standard injection molding tool. In this process, the blowing agent activates and pushes resin uniformly into the cavity pockets.  As the part cools, a solid skin forms against the mold. On the interior, the foaming action produces a honeycomb structure and reduces post-mold shrinking.

The color of your plastic part can be an important aspect of its perceived quality. In this industry, many of the materials (or resins) that are used are off-white, translucent, or yellow and those bland colors can have a negative impact on the appearance of your end product and your customers' opinion of the piece. Consequently, you should give serious consideration to the color of your parts.

If you’ve spent a significant amount of time in the plastics industry like us, you may have noticed a recent trend that’s picked up speed over the last few years. The utilization of lasers in plastic etching and engraving isn’t something completely new; the technology has actually been around for quite some time. It’s the recent improvements to the technology that has caught the eye of customers and plastics professionals alike.

Like most technical specializations, plastic injection molding has a vocabulary all its own. In some cases the terms are unique, in others they may be common terms but used in a unique way in our industry. All in all, there are probably hundreds of words in the plastic injection molding lexicon.

You’ve been asked to source small plastic parts for your company’s product (we define “small” as the size of your fingernail to the size of your hand), but are unfamiliar with the plastic injection molding process. Here’s a quick overview to give you a baseline understanding. And, of course, we’re always happy to answer your questions on the phone or via email.