This article explains the differences between A, B, and C injection-molding screws, which are distinguished primarily by diameter and length-to-diameter ratio. A-type screws offer high pressure and excellent mixing for engineering materials and precision thin-walled parts; B-type screws are the versatile default for over 70% of general-purpose plastics; C-type screws provide high capacity for large, thick-walled components. Three selection rules are provided: keep shot size within 30%–70% of screw capacity, choose fine high-pressure screws for transparent parts, and specify wear-resistant alloys for fiber-reinforced materials.
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Screw cleaning is critical to product quality in modified plastics production, yet often overlooked. This article analyzes four common cleaning methods for twin-screw extruders—resin cleaning, disassembly and manual cleaning, flame cleaning, and water-based cleaning—covering their operational principles, key process steps, precautions, and limitations. It provides practical guidance for selecting and combining cleaning methods based on material characteristics, equipment condition, quality requirements, and cost-effectiveness, while emphasizing standardized operations and regular maintenance to extend equipment service life.
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For PVC plastic extrusion production lines, feeding method selection depends on material form and process requirements. Three common systems are compared: spring feeders (quick to clean, suitable for frequent color changes but poor with high-filler powders), screw feeders (high flow rate and anti-bridging, ideal for high-filler powders but not for fiber-reinforced materials), and vacuum feeders (dust-free and closed-loop, best for cleanrooms and fiber reinforcement but limited at high output).
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