This section discusses the determination of channel depths H₁ and H₂ in venting screws, with emphasis on the pump ratio Ω (Ω = H₂/H₁). The pump ratio directly influences the risk of vent flooding and extrusion stability. A theoretical optimum Ω of 1.5 is derived for Newtonian fluids, while for non-Newtonian polymers like polyethylene an Ω of 1.75 yields maximum die pressure. In practice, most designs adopt Ω values between 1.5 and 2.0. The article also clarifies that the concept of a "second compression ratio" is invalid for venting screws, as the venting section is not fully filled.

This section outlines the functional characteristics of venting screws in extrusion. It identifies three main sources of gases in raw materials—entrained air, adsorbed moisture, and internal volatiles—and describes their detrimental effects on product quality and properties. While conventional methods rely on pre-drying or feed-throat venting, these approaches increase costs, risk contamination, and are often insufficient for high-speed extrusion. The text concludes that vented extruders offer superior performance in effectively removing these gases.

This article analyzes the economics of extruder screw design, focusing on energy consumption, service life, and manufacturability. It argues that design choices—such as specific energy, screw speed, L/D ratio, and mixing element complexity—must be systematically evaluated from an economic perspective rather than purely technical one.

Welcome to Visit Ningbo Superior Machinery at Chinaplas 2026Ningbo Superior Machinery is pleased to announce our participation in CHINAPLAS 2026, the world’s leading plastics and rubber trade fair. We welcome customers, partners and industry friends from all over the world to visit our booth for fac

Celebrate the Spring Festival with new hope and endless opportunities!May this brand-new year bring you steady growth, successful cooperation, and prosperous business. Wishing you and your family health, joy, and all the best in everything you do!Ningbo Superior Team

As the new year dawns with renewed vitality and all things take on a fresh look,all colleagues at Ningbo Superior extend our sincere New Year wishes to our domestic and overseas customers and partners who have always supported us!In the past year, we have focused on the field of plastic and wood pro