In-barrel drying is an innovative technique in plastic injection molding that involves drying polymers directly within the barrel of the injection molding machine. This method eliminates the need for separate drying equipment, streamlining the production process. It is particularly beneficial for moisture-sensitive polymers, including polyamides (nylons) and polyethylene terephthalate (PET), as it minimizes the risk of defects caused by moisture absorption.
Certain polymers, particularly those that are moisture-sensitive, require very careful drying before they can be injection molded. To address this, some injection molding machines are equipped with in-barrel drying functionality, which dries the polymer directly within the machine’s barrel before injection.
The barrel, a cylindrical component of the injection molding machine where the plastic material is melted, mixed, and prepared for injection, serves as the drying chamber. By utilizing the machine’s heating system, the polymer’s moisture content is reduced to acceptable levels. This process minimizes the risk of defects such as bubbles, voids, splay marks, decreased mechanical strength, and poor surface finishes in the final molded parts. In-barrel drying streamlines production, improves material quality, and eliminates the need for separate drying equipment.
Here is an injection molding machine with this feature in our plastic injection molding facility:
Highly hygroscopic polymers are materials that readily absorb moisture from the environment which can negatively impact their processing and performance if not properly dried. Here are some common examples:
If you are using an injection mold press that does not have in-barrel drying, the alternative is to use an external dryer that uses hot air to dehumidify the polymer. As you can see from our own facility, this large and bulky piece of equipment (shown here) sits next to the injection mold press and may not be practical for every facility, let alone affordable.
In-barrel drying offers several significant benefits in the plastic injection molding process, particularly for moisture-sensitive polymers.
Talk To Us About Your Tooling And/Or Plastic Injection Molded Parts Project
In-barrel drying is an innovative technique used in plastic injection molding to prepare polymers by drying them directly within an injection molding press machine’s barrel. We use this to eliminate the need for separate drying equipment like hot air dryers. This approach simplifies the plastic injection molding process and is especially valuable for moisture-sensitive polymers, such as polyamides (nylons), PET, and others, as it reduces the risks of defects.
Some polymers must be specially dried before being injection molded, and some machines include In-barrel drying functionality that dries the polymer before it is injected.
The drying occurs in the barrel (the cylindrical component of the injection molding machine where the plastic material is melted, mixed, and prepared for injection into the mold), leveraging the heat and vacuum environment of the machine. This drying reduces the polymer’s moisture content to acceptable levels, reducing the risks of defects such as bubbles or voids in the part, splay marks, reduced strength, and poor finishes.
Here is an injection molding machine with this feature in our plastic injection molding facility:
Hygroscopic polymers that attract and absorb moisture will benefit from drying. They are very commonly used. Some examples include:
If you are using an injection mold press that can’t dry polymers itself, then the alternative is to use an external dryer that uses hot air to dehumidify the polymer. As you can see from our own facility, this is a large and bulky machine (on the right) that sits next to the injection mold press and may not be practical for every facility, let alone affordable.
There are a few obvious benefits that make utilizing injection molding machines that can dry polymers in their barrels desirable:
