I. Basic Parameter Matching Verification
1. Length-to-Diameter Ratio: 25-30 for conventional PPR extrusion, 28-32 for high-temperature PEEK processing, and 36-44 for high-filler wood-plastic composites, adapting to the plasticizing residence time requirements of different materials.
2. Compression Ratio: 2.5-3.5 for PPR, 2.8-3.2 for PEEK, and 3.5-4 for high-filler wood-plastic composites, avoiding material degradation due to overheating or insufficient compaction.
3. Screw Type: Select a sudden-change screw for crystalline PPR, a gradually decreasing low-shear screw for non-crystalline heat-sensitive materials, and a barrier screw with a mixing section for high-filler modification.
II. Working Condition Adaptation Details Verification
1. Screw Section Distribution: Feeding section accounts for 50%-55%, melting section 20%-25%, and homogenization section 20%-25%, ensuring the rhythm matching of material conveying, melting, and metering.
2. Special Structure Avoidance: When processing high-temperature, high-viscosity materials such as PEEK, the continuous compression PVC-type screw structure is prohibited; when processing transparent/heat-sensitive materials, a mixing ring should not be added to the front end to avoid overheating and discoloration of the material.
3. Gap Control: The gap between the screw and the barrel should be controlled at 0.05-0.08mm. Under conditions of strong corrosion/high wear, the gap needs to be further reduced to prevent backflow from affecting the discharge accuracy.
III. Material and Process Compatibility Verification
1. Substrate and Surface Treatment: When processing high-wear materials containing glass fiber, select 38CrMoALA nitrided steel or bimetallic sprayed material; when processing highly corrosive materials, select stainless steel or PEEK-coated screws to avoid premature failure.
2. Actual Trial Run Verification: Run continuously for 2 hours and check the uniformity of plasticization of the discharge. If there are no black spots, no melt fractures, product wall thickness fluctuations ≤ ±5%, and no traces of localized overheating degradation, the material is considered compatible.
