Within the world of custom injection molding, there’s a wide range of new vocabulary terms for many first-timers. Plastic molding is a detailed and thorough process, one that requires a high degree of training and expertise, so it’s no surprise there are a number of terms that may be confusing for those without such training.

At EnviroTech Custom Injection Molders, we’re proud to offer not only a wide range of custom injection molding and similar services but also friendly professionals who are happy to explain the ins and outs of our processes to our clients as needed. We may not be able to turn you into an injection molding pro overnight, but we’ll absolutely take the time to detail certain important factors that relate to your project. With this theme in mind, this two-part blog will go over some of the simpler terms you might hear from our team – what they mean, what you need to know about them and how they might impact your project.


You need raw material to create a finished part within plastic injection molding, and resin is this material. It’s available in numerous styles and formats, and one of the key elements of any injection process will be selecting the proper resin that fits your needs. This is an area where our team will provide a consultation that leverages our expertise in this realm.

Mold and Mold Cavity

These projects also require a hollow form for plastic to be injected or inserted into, and this is generally referred to as a mold. Molds are most commonly made from stainless steel, but can also come from other materials in some cases. Molds have to be made with detail and accuracy to ensure precision in the final build.

The actual hole itself, one that’s shaped to fit the desired part, is known as the mold cavity. Multiple cavities can be made in a given mold – the more cavities, the greater the cost tends to be. Generally speaking, for projects of our scale and detail, it’s recommended that you create one mold per part, rather than “family molds” that have different cavities for different parts.


When it comes to the color of a given project, a colorant pigment system – usually either pellets or liquids – will be mixed with the resin to create the color you want. This involves a color matching process where we’ll help you develop a specific color concentrate for your project.

Wall Thickness

There are many factors that impact the cost of an injection project, and wall thickness might be the most significant one. Usually, companies strive to mold the thinnest wall possible, but here at Envirotech, we exceed the bounds of common design techniques and have created a proprietary technology that allows us to mold cross-sectional wall thicknesses up to 5 inches.

Flash and Burrs

These are terms that mean the same thing: They refer to thin, wafer-like protrusions that may show up on a finished part. They’re caused by melted resin that escapes from the mold cavity, most common among parting lines or ejector pins. In most cases, simple process optimization will fix a flashing issue; in those where aged or poorly designed molds are the cause, however, a redesign might be needed.

For more on the vocabulary associated with custom injection molding, or to learn about any of our services, speak to the staff at EnviroTech Custom Injection Molders today.