In compounding, various materials (polymers, additives, etc.) are mixed and melted—generally in an extruder of some type—then pelletized. Most compounding extruders purchased nowadays are of the twin-screw corotating/intermeshing variety, though counterrotating twins are used for some applications. Compounding extrusion lines are typically equipped with gravimetric feeding systems that dose materials into the extruders at very specific rates. In certain applications, extruders are equipped with vent ports that pull unwanted moisture and other volatiles from the polymer stream.

How to Configure Your Twin-Screw Extruder -- Part 2

Follow these tips to configure your twin-screw elements to promote feeding and solids conveying.

Compounding: Essential Reading

What to Know About Your Materials When Choosing a Feeder

Feeder performance is crucial to operating extrusion and compounding lines. And consistent, reliable feeding depends in large part on selecting a feeder compatible with the materials and additives you intend to process. Follow these tips to analyze your feeder requirements.

How to Configure Your Twin-Screw Barrel Layout

In twin-screw compounding, most engineers recognize the benefits of being able to configure screw elements. Here’s what you need to know about sequencing barrel sections.  

Improving Twin-Screw Compounding of Reinforced Polyolefins

Compounders face a number of processing challenges when incorporating a high loading of low-bulk-density mineral filler into polyolefins. Here are some possible solutions.

The Path to Pellet Perfection

In underwater pelletizing, numerous variables in the equipment, process and material affect pellet shape, consistency and quality factors such as fines. Defining the “perfect” pellet depends on the conditions of end use, and achieving that ideal requires understanding  of the causes of imperfections.

10 Ways to Improve Twin-Screw Compounding Performance

There are many techniques known to operators and plant engineers for increasing the performance of a twin-screw compounding extruder.


FAQ: Compounding

How can I optimize my twin-screw compounding process?

We identify problems in compounding as “chronic” if the results are the same every time a particular formulation is run. For these problems, the treatment requires redesigning the screw configuration or modifying the compounding process. This is the only way to cure such problems.

Many new players have emerged in the biopolymer space with new materials and many new formulations. Co-rotating twin-screw extruders provide excellent material mixing capabilities for all polymers, including biopolymers. You should consider your machinery supplier as a development partner to achieve your goals in the areas of melt and mix quality, production rates, and other parameters, regardless of formulation. Make sure your machinery supplier has the facilities and the know-how to help you test material formulations and improve your processes.

Pelletizers are essential components in resin manufacture, compounding, masterbatch production, and recycling. A high-volume system that is appropriate for a polymerization plant will be very different from one that suits the needs of a toll compounder. One that can produce micropellets for use in masterbatch may not be the best choice for processing post-consumer regrind. Here are some different types of pelletizers.


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