Twin-screw extruders are classified into co-rotating and counter-rotating types based on the screw rotation direction. These two configurations have distinct characteristics due to differences in rotation direction and screw geometry.

Counter-rotating Twin Screw Extruders
Generate lower shear stress, making them suitable for materials that need to avoid excessive heat generation caused by shear.

Co-rotating Twin Screw Extruders
Feature high shear stress between the screws, enabling powerful mixing.

Co-Rotating Twin Screw Extruders

①　Screw Rotation Direction

The two screws rotate in the same direction. As the screws intermesh and rotate, materials flow effectively between the screws.

②　Mixing Performance

Co-rotating twin-screw extruders offer high shear force between the screws, enabling powerful mixing. They are especially suitable for applications requiring uniform mixing of complex materials or high-performance mixing.

③　Applications

Used in the production of polymer composites, development of new materials, and applications requiring strong mixing capabilities. For instance, they are ideal for dispersing fillers in nanocomposites such as carbon nanotubes (CNTs) or cellulose nanofibers (CNFs).

　

Counter-Rotating Twin Screw Extruders

①　Screw Rotation Direction

he two screws rotate in opposite directions. As the screws rotate, materials are drawn into the intermeshing zone and transported.

②　Mixing Performance

Compared to co-rotating extruders, counter-rotating extruders have lower shear force, making them suitable for processing materials that need to avoid shear-induced heat generation.

③　Applications

Ideal for processing materials like PVC, where shear-induced heat must be minimized. Commonly used in applications requiring low-speed, stable extrusion.

　

Key Characteristics of Counter-Rotating Twin Screw Extruders

Counter-rotating extruders excel in processing materials with poor thermal stability and low flowability, such as rigid PVC. Their lower shear stress allows extrusion at lower temperatures, making them suitable for manufacturing products like PVC pipes, sheets, and profiles.

The calender effect between the screws enhances dispersion mixing of additives such as pigments and lubricants. The intermeshing screw sections act like calender rolls, providing compression and extension effects for efficient mixing.

Twin Screw Extruders by Technovel
– A Dedicated Japanese Extruder Manufacturer

　

As a world-first innovation, we have developed a new type of horizontal multi screw extruder. Our Quad screw and Octa screw extruders are already being utilized across various industries. Even in the field of conventional twin screw extruders, we offer a wide lineup ranging from ultra-compact models—such as the world’s smallest 6 mm diameter screw and our best-selling 15 mm model—to large-scale production machines.

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