TME

所属分类: Mixed component

TME is a gear-disc type distributive mixing element for co-rotating twin-screw extruders. The disc has multiple teeth around its outer edge and is a kneading element without forward conveying capability. It features a modular involute spline assembly, used in sets, and is often installed on the screw core along with transitional isolation rings.

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Detailed description

Technical Details of TME

Structural Geometry

Disc-shaped base body with multiple straight / helical teeth distributed along the circumference. Teeth can be designed with forward, neutral or reverse inclination angles. The element itself has no screw lead and provides no forward conveying capacity. The toothed discs of twin screws are arranged in staggered tangency without meshing wiping contact. The inner bore adopts involute spline; normally used in groups with spacer rings installed between groups. It has no self-wiping self-cleaning structure and features local material stagnant dead zones.

Material Configuration

• 38CrMoAlA nitrided steel: General compounding with good cost-performance.

• WR5: For general wear-resistant working conditions.

• WR13: Wear and corrosion resistance for corrosive materials.

• Nickel-base alloy, high-speed steel W6: For highly corrosive and heavily abrasive service conditions.

Manufacturing Process

Integral forging and heat treatment. CNC milling for tooth profile machining. Root fillets reduce stress concentration. Dimensional accuracy controls the clearance between toothed disc and barrel, and the sharpness of tooth tips is controllable.

Process Parameter Characteristics

• Shear level: Medium shear

• Conveying capacity: Almost no forward conveying, prone to local pressure build-up

• Shear heat: Medium, higher than SME and lower than KB kneading blocks

• Mixing type: Extremely strong transverse distributive mixing, weak dispersive mixing

• Residence time: Obviously prolonged with wide residence time distribution • Self-cleaning: Poor with stagnant dead zones; heavy cleaning workload for material or color changeover

Functions of TME

•Strong transverse flow splitting and homogenization: The toothed discs split the melt flow with repeated flow division and recombination, realizing transverse homogenization of melt temperature, components and fillers, and eliminating radial differences in composition and temperature. Its large specific surface area facilitates intermixing of multi-phase systems.

• Glass fiber wetting and dispersion: TME installed after the side feeding section for glass fibers improves resin wetting on glass fibers and breaks up glass fiber bundles. Compared with KB kneading blocks, it causes less excessive fiber breakage and is suitable for glass fiber reinforced formulations.

• Improve preconditions for devolatilization: Increase the renewing surface area of melt and boost removal efficiency of small-molecule volatiles in venting sections; installed upstream of vacuum devolatilization zone.

•Build local backpressure: Without conveying capability, grouped installation can establish local backpressure, raise melt pressure and promote sufficient wetting of fillers and additives.