Technical Details of Alloy Liner Assembly for Triple‑Screw Extruder1. Material & StructureBase body: 42CrMo / 40Cr alloy steel, quenched and tempered to ensure overall strength and deformation resistance under high temperature and high pressure. Alloy inner lining: Nickel‑base + tungsten carbide hard alloy manufactured by centrifugal casting / static sintering; cobalt‑base alloy is selected for some highly corrosive working conditions. Alloy layer thickness: 1.5～3.0 mm Alloy layer hardness: HRC 58～64 Process requirement: The inner alloy layer forms metallurgical bonding, free from peeling. Defects such as pores, cracks and slag inclusions are not permitted. 2. Key Geometric ParametersTriple‑hole layout: Three parallel circular holes with equal spacing; every two holes intersect to form intermeshing cavities. Inner bore diameter: Matched according to screw outer diameter, commonly Φ20～Φ90 mm. Center distance: Designed based on machine model with extremely tight tolerance for the center distances of three bores. Liner length: Segmented structure; the length of each liner segment is customized according to barrel modules. Inner bore surface roughness: Ra≤0.8 μm to reduce material friction and accumulation. Geometric tolerance: Coaxiality, cylindricity of the three bores and tolerance of inter‑bore center distances represent the biggest challenge in machining. 3. Working Performance ParametersOperating temperature: Ambient temperature ～ 350 °C Internal material pressure: Max. 50 MPa Applicable materials: Glass‑fiber reinforced plastics, high‑filled materials with calcium carbonate / talc powder, PVC, PLA/PBAT biodegradable materials, carbon black conductive materials and other highly abrasive, mildly corrosive materials. Failure modes: Abrasion, alloy layer spalling, corrosion, carbonized material buildup. 4. Machining & Inspection Key PointsRough machining of base body → sintering alloy on inner wall → fine boring and honing of triple bores. Inspection items: Alloy layer thickness, hardness, metallographic examination, flaw detection, triple‑hole center distance, cylindricity, penetrant testing (PT) for cracks. Assembly: Press‑fitted into barrel base with interference fit to prevent loosening under high‑temperature operation. | Functions of Alloy Liner for Triple‑Screw Extruder• Abrasion resistance protection: Resist abrasive wear caused by fillers (e.g. glass fiber, mineral powder) on barrel inner wall. • Corrosion resistance protection: Isolate chemical attack on barrel base from corrosive additives, flame retardants and other agents. • Guarantee material purity: Prevent material contamination by impurities generated from barrel rusting or wear, which is critical for lithium battery, pharmaceutical and other industries. •Maintain pressure and output: Keep smooth inner surface, reduce material leakage and backflow to ensure stable working pressure built by screws. • Withstand high torque: Provide rigid supporting surface under high rotating speed and high torque of screws. |
