In previous entries to this multi-part blog series, we’ve gone over a number of important terms and areas to be aware of within the injection molding world. Whether you’re a client making an order from an injection molder, a molding professional or anyone in between, a general knowledge of molding terminology makes the entire process simpler and easier to navigate.

At EnviroTech Custom Injection Molders, we’re happy to offer not only numerous plastic injection molding and related services, including machining areas like finishing, but also expertise and information on any of our materials, products or services that our clients might require. Today’s final entry in our series will cover a few other terms it’s good to know when running in injection molding circles of any kind.

End-of-Arm Tooling

Within the injection molding process, our team is always looking for ways to improve speed and efficiency – which improve your cost savings as a client. One of the key tools at our disposal here is robotics.

There are a few different robotics pieces that may be used in injection molding. Maybe the most well-known is referred to as End-of-Arm Tooling (EOAT), a complex system that’s assembled alongside electronics, pneumatics and sensors to hit specific processing needs or goals. There are also other simpler forms of robotics used in molding, such as spruce pickers.

Hopper and Barrell

Injection molding also requires some storage capabilities for the process to be completed, and both a hopper and barrel will often be used here. The hopper stores the plastic that will be eventually used in the process, and may have a dryer unit included to dry the plastic for processing and keep external moisture away. In other cases, the hopper will contain small magnets to stop the wrong metallic particles from entering the machine.

Plastic will be taken from the hopper and then melted using heater bands, injected into a mold cavity. The material is melted in the barrel we mentioned above, where it’s controlled and then eventually injected into the machine mold.


Finally, various injection molding presses will be rated based on their tonnage, or the amount of clamping pressure they are able to generate. Also known simply as press force, tonnage within injection molding can range all the way from under five tons to over 4,000 in some cases.

The higher a machine’s tonnage is rated, generally the larger the machine will be. Tonnage will be considered alongside material chosen, part size and other variables when determining how to proceed with a given injection mold.