Technical Details of Open‑Type LinerStructural Geometry• The inner bore adopts a figure‑eight (∞) intermeshing flow channel for twin‑screw. A through opening matching the barrel window is machined on the upper part of the liner, with smooth transitional contours at the opening to minimize material buildup and adhesion. • C‑type (split open‑type liner): Two‑piece split structure installed inside the barrel housing for easy assembly and disassembly. Micro‑gaps at the joint seam carry a slight risk of material accumulation. • Monolithic open‑type liner: Integrally formed figure‑eight bore with high structural strength and no joint seams. It delivers better self‑cleaning performance than the C‑type liner, yet requires higher machining difficulty and production cost. • The outer diameter is interference‑fitted with the barrel housing. Locating shoulders at both ends ensure circumferential and axial positioning to prevent axial shifting and circumferential rotation during operation. Material Configuration• 38CrMoAlA nitrided steel: For general modification applications; nitrided for good cost‑performance ratio. • WR5 dual‑alloy: For general high‑wear modification conditions. • WR13 powder alloy: Wear‑resistant and corrosion‑resistant, suitable for battery slurry and corrosive materials. • Nickel‑base alloy / Hastelloy: For highly corrosive systems such as fluoroplastics and special materials. Manufacturing Process• Forged blank with quenching‑and‑tempering heat treatment. • Precision CNC machining of the figure‑eight inner flow channel. • Rounded transition at the opening window. • Inner surface treated with hard‑alloy cladding or nitriding. • Strict tolerance control for twin‑bore center distance and inner‑bore dimensions to maintain proper clearance against screw elements. Process Parameter Characteristics• Maximum operating temperature: 350 °C • Fitting mode: Interference fit between liner and barrel housing • Internal bore clearance: 0.2‑0.4 mm unilateral clearance with screw elements (varies by machine model) • C‑type liner: Easy assembly and disassembly; minor material accumulation risk at joint seam. • Monolithic liner: No joint seams, good anti‑buildup performance and longer service life. | Functions of Open‑Type Liner•Wear protection for barrel housing: Directly contacts materials and screws, enduring shear wear and melt corrosion. Only the liner needs replacement after wear, protecting the costly barrel housing and lowering equipment operating costs. •Enable feeding and devolatilization process windows: Aligned with barrel windows to realize main feeding, side‑feeding of fillers, and vacuum venting. Moisture, monomers and small‑molecule volatiles are extracted through the window to meet devolatilization requirements for compounding and pelletizing. • Form complete figure‑eight flow channel for proper screw intermeshing: Provides the figure‑eight working cavity for twin‑screw operation. Controls clearance between screws and barrel inner wall to maintain process conditions for melt pressure building, conveying and mixing. •Optimize material flow and reduce stagnation & adhesion: Rounded‑edge design at the opening window reduces risks of melt wall‑sticking and charring. Monolithic open‑type liners with no joint seams are more suitable for frequent color‑change and heat‑sensitive material production. •Support temperature‑control heat exchange: The outer wall of the liner is in close contact with the heating/cooling channels of the barrel housing for efficient heat transfer and precise material temperature control. |
