SK Conveying Screw Element For Twin Screw Extruders Full SK Series Pitch Feeding Blocks

SK Conveying Screw Element for Twin Screw Extruders | Full SK Series Pitch Feeding Blocks

SK conveying screw elements are specialized single-forward-flight modular spare parts designed exclusively for intermeshing co-rotating twin screw extruders, widely applied across feed throat, mid-melting transition, side feeder transfer and pre-vacuum devolatilization barrel zones. Different from standard twin flight conveying blocks, SK series adopts flat-cut thrust flight design, expanding internal free volume by 15%–40% to eliminate powder bridging, material slipping and feed blockage for low bulk-density fillers, fine powder and recycled flakes.

All SK conveying segments feature unified standard multi-tooth internal splined bore, fully interchangeable with matched SK series core shafts. Multiple alloy material options are supported with integral gas nitriding treatment to reach HRC 58–62 uniform surface hardness for long-term anti-wear compounding production.

1. Enlarged free volume flat thrust flight: Optimized flat cutting flight surface delivers stronger axial pushing force, solves feed bridging of talc, carbon black, wood powder and lightweight recycled materials; avoids backflow at main feed throat.
2. Modular split combination system: Two length options per pitch realize flexible layout; single full-loop block for continuous stable transport, multiple stacked short segments for staged gradual pressure build-up without sharp pressure spikes.
3. Universal interchange spline: Standard SK series splined hole for all pitch sizes, no need to replace screw shafts when adjusting screw layout formulas.
4. Premium wear-resistant metallurgy: W6Mo5Cr4V2 high speed steel, 1.2343 hot work steel and HIP powder alloy available; two-stage gas nitriding guarantees long service life for high-filler masterbatch mass production.
5. Multi-position cross-scenario compatibility: Large pitch SK96 for feed inlet only; medium/medium-small pitch SK72 & SK64 for melting, side feeding and vacuum vent buffer zones.

• SK 96/96 Full-Loop: Single complete spiral, maximum throughput for high-density pellets, coarse powder; installed at primary raw material feed throat of extruder barrels.
• SK 96/48 Compact Half-Length: Stackable short segment for feed transition buffer, avoids flow overflow of low-density powder before melting zone.
  Core application: PP/PE virgin pellet feeding, high-filler recycled plastic granulation, large-volume masterbatch production lines.

• SK 72/72 Full-Loop: Continuous uniform melt transport, stabilizes solid-to-melt phase transformation between feed section and mixing kneading blocks.
• SK 72/36 Compact Half-Length: Gradient pressure adjustment for narrow modified barrels, mild compression to prevent heat-sensitive polymer foaming.
  Core application: General engineering plastic compounding, medium-density color masterbatch, glass fiber filled PA/PC melting transport.

• SK 64/64 Full-Loop: Standard long-distance melt conveying for full-length melting barrels, consistent baseline pressure before mixing sections.
• SK 64/32 Compact Half-Length: Specialized pre-vacuum vent buffer segment, stabilizes melt flow to reduce volatile surging during devolatilization.
  Core application: Biodegradable PLA/PBAT extrusion, low-density fine powder masterbatch, side feeder auxiliary material transfer, vacuum degassing compounding.

Standard Surface Process: Integral two-stage gas nitriding + precision mirror polishing, smooth flight surface reduces melt stagnation and carbon deposition.

Complete extrusion screw gradient sequence from feed to die:

1. Main feed throat: SK96/96 (high throughput feeding)
2. Feed transition buffer: Stacked SK96/48
3. Main mid-melting transport: SK72/72
4. Narrow barrel gradient compression: Stacked SK72/36
5. Late melting stable conveying: SK64/64
6. Vacuum vent front flow buffer: Stacked SK64/32
7. Followed by KB kneading mixing blocks & small pitch SK56/SK44 metering segments

For heat-sensitive bioplastic / low-density fine powder formulas: Cancel all full-length XX/XX blocks, adopt full stacked half-length short segments to avoid excessive single-stage pressure.

Share your extruder model, barrel layout, production raw material type and target throughput with our professional extrusion engineering team. We provide free customized gradient screw layout design for all SK96/SK72/SK64 conveying screw elements, lab test sample supply and factory-direct bulk wholesale price for twin screw extruder spare parts. Contact us via WhatsApp or email to download complete technical dimension drawings and full series price list.