Advanced Single-Screw Extruders by EXTRUTEX Austria

Optimized for Polyolefin Pipe Production

Introduction

In the fast-growing field of polymer processing, extrusion technology continues to evolve as manufacturers demand higher efficiency, greater precision, and enhanced product quality. Nowhere is this more evident than in the production of polyolefin pipes—including HDPE, LDPE, PP, PPR, and PEX—which form the backbone of modern infrastructure, water supply, sewage, gas distribution, and heating/cooling systems.

At the heart of these production lines stands the extruder—the machine responsible for melting, homogenizing, and delivering polymer melt with the precision required for continuous pipe extrusion. For decades, single-screw extruders have been the standard solution in this sector due to their robust design, relatively simple operation, and cost-effectiveness. However, as the demands of industry rise, traditional single-screw systems are no longer sufficient.

EXTRUTEX Austria has responded to this challenge by developing a new generation of single-screw extrudersequipped with grooved feed bush technology and the innovative “HELIFEED” screw geometry. This breakthrough design has dramatically increased throughput, reduced torque demand, improved melt homogeneity, lowered melt temperatures, and enhanced the physical properties of the final pipe. The result is not only superior product quality but also a significant reduction in energy consumption—a decisive factor in today’s competitive and sustainability-driven markets.

The Role of the Single-Screw Extruder in Pipe Production

Before diving into the innovations introduced by EXTRUTEX, it is important to understand the fundamental role of a single-screw extruder in the pipe extrusion process.

A single-screw extruder is essentially a polymer processing engine. It performs three primary functions:

1. Feeding and Conveying: Solid polymer granules (pellets) are introduced into the extruder’s feed zone and transported forward.

2. Melting and Homogenization: As the screw rotates, mechanical energy and heater bands convert the solid polymer into a homogeneous melt.

3. Metering and Pumping: The extruder delivers a consistent flow of molten polymer under stable pressure to the die head, where the pipe profile is shaped.

For polyolefins like HDPE and PP, which are semi-crystalline thermoplastics, the control of melting and mixing is critical. Poor homogenization results in pipe defects, dimensional instability, weak weldability, and reduced lifetime performance.

Challenges in Conventional Single-Screw Extruders

Traditional single-screw extruders, while reliable, face several limitations in processing modern polyolefins:

• Throughput vs. Energy Trade-off: Higher outputs often require higher torque and energy, leading to increased operational costs.

• Inconsistent Melting: Non-uniform melt leads to flow instabilities, wall thickness variation, and surface defects in pipes.

• High Melt Temperature: Excessive thermal exposure can degrade polyolefins, reducing mechanical properties and long-term performance.

• Limited Material Flexibility: Standard screws may struggle to handle diverse resin grades (HDPE vs. PPR vs. PEX) without performance losses.

• Operator and Maintenance Burden: Inefficient designs consume more power, require more cooling, and demand frequent servicing.

To address these limitations, EXTRUTEX engineers reimagined the design of the single-screw extruder from the ground up.

The EXTRUTEX Innovation: Grooved Feed Bush + “HELIFEED” Screw Geometry

The new generation of EXTRUTEX extruders introduces two decisive innovations:

1. Grooved Feed Bush (Feed Liner):

   • Located at the feeding zone of the extruder, the grooved bush significantly improves the frictional grip between polymer granules and the screw flight.

   • This prevents slippage, stabilizes solid conveying, and increases the pressure build-up capacity.

   • The result is a much higher feeding efficiency, even when processing low bulk-density materials like LDPE.

2. HELIFEED Screw Geometry:

   • This proprietary screw design optimizes the geometry of flights, channels, and compression ratios.

   • The HELIFEED system ensures faster melting, gentle homogenization, and more uniform temperature distribution across the melt.

   • By lowering torque demand, the extruder requires less drive power, further reducing energy consumption.

Combined Effects

When the grooved feed bush and HELIFEED screw are combined, the results are dramatic:

• Higher Output: Production rates increase without requiring larger extruders.

• Lower Torque: Mechanical load on the gearbox and motor is reduced.

• Improved Melt Quality: Homogeneous melt ensures smooth surfaces, uniform wall thickness, and enhanced weldability.

• Reduced Melt Temperature: Gentle processing prevents thermal degradation, preserving mechanical strength and elongation properties.

• Energy Savings: Lower torque and reduced thermal load lead to substantial electricity savings.

Technical Benefits in Detail

1. Increased Throughput

In conventional single-screw extruders, output often plateaus due to inefficient feeding and limited melting capacity. With grooved feed technology, EXTRUTEX extruders achieve a 20–40% increase in throughput compared to older designs.

2. Reduced Torque Demand

Torque is a critical parameter in extruder operation. High torque strains the gearbox, bearings, and motor, leading to higher wear and maintenance costs. The HELIFEED design reduces torque demand by up to 25%, ensuring longer equipment life and lower operating costs.

3. Superior Melt Homogeneity

A uniform melt ensures that every meter of pipe has consistent mechanical properties. Melt homogeneity is crucial for:

• Pressure-rated HDPE water pipes

• Gas distribution pipes requiring leak-proof weldability

• PEX and PPR pipes where dimensional accuracy is vital

EXTRUTEX extruders achieve a homogeneity index far superior to conventional screws, verified through rheological and ultrasonic testing.

4. Lower Melt Temperatures

Excessive melt temperature can lead to:

• Oxidative degradation of PE and PP

• Reduced long-term hydrostatic strength of pipes

• Higher cooling demand downstream

By improving mixing and melting efficiency, EXTRUTEX extruders lower melt temperatures by 10–20°C, preserving polymer integrity.

5. Energy Efficiency

Perhaps the most significant advantage is energy savings. In some installations, EXTRUTEX extruders have reduced specific energy consumption (kWh/kg) by up to 30%. This directly reduces production costs and carbon footprint.

Applications in Pipe Extrusion

The versatility of EXTRUTEX single-screw extruders makes them suitable for a broad spectrum of polyolefin pipes:

• HDPE Pipes: Water distribution, sewage, and gas pipelines (up to large diameters).

• PP/PPR Pipes: Hot and cold water systems, industrial wastewater, push-fit connections.

• PEX & PERT Pipes: Underfloor heating and cooling systems.

• LDPE Pipes: Irrigation and cable conduits.

Each application benefits uniquely from the improved melt quality, energy efficiency, and higher throughput of EXTRUTEX extruders.

Comparative Advantage Over Conventional Designs

Economic and Environmental Impact

• Cost Savings: Lower energy bills, reduced maintenance, and higher output all contribute to lower cost per meter of pipe produced.

• Sustainability: Energy-efficient design reduces carbon emissions and supports green manufacturing initiatives.

• Long-Term Investment Value: With reduced mechanical stress and optimized operation, equipment life is extended, ensuring a better return on investment.

Case Study Example (Illustrative)

A mid-sized pipe producer in Eastern Europe upgraded from a conventional 90 mm single-screw extruder to a new EXTRUTEX HELIFEED-equipped model:

• Before:

  • Output: 450 kg/h HDPE

  • Energy consumption: 0.35 kWh/kg

  • Melt temperature: 225°C

• After Upgrade:

  • Output: 620 kg/h HDPE (+37%)

  • Energy consumption: 0.24 kWh/kg (−31%)

  • Melt temperature: 208°C

  • Pipe quality: Smoother surface, improved ovality, fewer defects

This resulted in annual savings exceeding €80,000 in energy costs alone, with a payback period of less than 18 months.

Future Outlook: The Next Generation of Extrusion Technology

As markets demand larger diameter pipes, higher production speeds, and environmentally sustainable solutions, extrusion technology must continue to evolve. EXTRUTEX is already working on:

• Digital Twin Integration: Real-time monitoring and simulation of screw performance.

• AI-Driven Process Control: Automated adjustments to optimize energy use and melt quality.

• Hybrid Heating Systems: Combining electric and induction heating for further efficiency gains.

• Circular Economy Readiness: Enhanced ability to process recycled polyolefins without compromising product quality.

Conclusion

The EXTRUTEX single-screw extruder represents a milestone in polyolefin pipe production. By integrating grooved feed bush technology with the advanced HELIFEED screw geometry, EXTRUTEX has overcome the traditional limitations of single-screw extrusion. The outcome is:

• Higher throughput

• Lower torque and energy consumption

• Improved melt quality and pipe properties

• Longer equipment life and reduced operating costs

For manufacturers seeking a competitive edge in today’s demanding markets, EXTRUTEX extruders are not just machines—they are strategic investments in efficiency, quality, and sustainability.