A parallel twin-screw and barrel assembly consists of two identical screws placed side-by-side with constant center-line distance throughout their length, housed within a matching figure-8 barrel bore. Unlike conical systems, the screw diameter remains uniform from feed to discharge, providing consistent volume capacity and shear control along the entire length. Key Technical Specifications Design Type: Parallel Twin-Screw (Co-rotating or Counter-rotating)Diameter Ratio: Constant screw outer diameter ($D$) across the entire length/D Ratio: Typically ranges from 22:1 up to 36:1 or higher, depending on processing needs Material & Treatments: High-grade alloy steels (e.g., 38CrMoAlA), nitrided, bimetallic alloy linings, or hard chrome plated for high wear and corrosion resistance Primary Applications PVC Processing: Extrusion of rigid and flexible PVC pipes, profiles, sheets, and foam boards Compounding & Masterbatch: High-output blending, filler reinforcement (calcium carbonate/glass fiber), and color compounding Recycling: Pelleting and re-granulation of post-consumer or industrial plastic waste High-Output Lines: Preferred for continuous, large-scale production requiring uniform plasticization and pressure stability Core Advantages Uniform Shear & Temperature Control: Constant diameter ensures consistent shear distribution and thermal history along the barrel. High Throughput: Delivers high output rates per hour compared to equivalent-sized conical systems. Modular Versatility: Screws can often feature segmented mixing and kneading elements customized for specific resin formulations. Extended Wear Life: Bimetallic barrel construction provides strong protection against abrasive additives and corrosive gases. Are you looking for specific sizing recommendations, material grades, or processing guidelines for a particular polymer?
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