Co-Rotating Twins
Segmented co-rotating twin-screw barrels and screws for PVC, profiles and pipe extrusion.
PENA® co-rotating twin-screw assemblies are primarily used in PVC processing (powder or pellets), profile extrusion, pipe production, pre-compounding and recycling applications. They are typically manufactured in modular segmented configurations to optimise processing performance, simplify maintenance and allow different materials to be used in each section of the extruder.
Typical Applications
- PVC pellet pre-compounding systems with additives for subsequent single-screw extrusion.
- PVC profile extrusion from powder.
- PVC pipe extrusion from powder.
- Recycling and Polywood-type applications.
Barrels (Segmented Design)
Modular System and Segment Types
- Modular barrels manufactured in individual segments, typically 4D and also available in 8D configurations.
- Typical processing lengths range from L/D 40 to L/D 52, with shorter feeding sections when required.
- Available segment types include feed, venting, injection, side feeder and closed sections, which can be combined according to process requirements.
- Integrated internal cooling circuits are available in both cylindrical and rectangular configurations.
Available Designs
- A) One-piece segment manufactured from 1.8509 or 1.8550 steel, nitrided to approximately 70 HRC with an effective layer thickness of around 0.5 mm.
- B) Segment with an outer body and replaceable inner liner, providing greater flexibility, easier maintenance and lower lifecycle costs.
- For 4D segments, bimetallic liners generally become the most cost-effective solution from Ø95 mm upwards. For 8D segments, this threshold is typically Ø70 mm.
Technical Barrel Solutions
| Solution | Technology | Material / Alloy | Recommended Application |
|---|---|---|---|
| Nitrided | Monobloc Segment | 1.8509 / 1.8550 | Standard applications and moderate wear conditions. |
| Hardened Liner | Replaceable | 1.2379 (K110/TPT60) | Medium abrasion and corrosion resistance requirements. |
| PM Liner (Powder Metallurgy) | Replaceable | CPM 10V / CPM420V / M390 / WR13 | High abrasion and/or corrosion resistance, depending on grade selection. |
| Bimetallic Liner | Centrifugally Cast (Figure-8 Design) | PENA 40 / PENA 51 / PENA 80 | Recommended for larger diameters and severe wear conditions, selected according to the processed polymer. |
Technical Advantages Barrels
- Fast maintenance, replacing only a segment or liner rather than the complete assembly.
- Material selection optimised for each process zone, including feeding, side feeding and venting sections.
- Improved cost-to-service-life ratio when using replaceable liner configurations
Screws (Shafts & Segments)
System Design
- The screw assembly typically consists of a high-strength shaft and individual screw elements mounted onto the shaft.
- The screw elements are selected according to the required process function, conveying, mixing, compression or venting.
- Hardened elements are not refurbished and are replaced once the wear limit has been reached.
Typical Materials
- Shafts: 1.6511 (36CrNiMo4 / 4340) or 1.2343 (H11), selected for their excellent torsional strength. 1.2343 is recommended for corrosive applications.
- Standard elements: 1.2379 (K110 / TPT60), hardened and heat treated.
- PM elements (Powder Metallurgy): CPM 10V (TPP1060), CPM420V (TPP15), M390/440C (TPP1959) and high-chromium WR13 (TPP25).
- Food processing applications: Special APX4 elements with Stellite coating, depending on the configuration.
Technical Screw Solutions
| Element | Solution | Key Benefit |
|---|---|---|
| Shaft | 0.01 mm Chromium Flash Coating (Optional) | Enhanced corrosion resistance and durability in severe operating conditions. |
| Elements | Hardened (Standard) or PM-HIP | Optimised according to abrasion and corrosion requirements, with maximum dimensional stability. |
| Food Processing Elements | APX4 + Stellite | Excellent hygiene and compatibility with food-grade processing applications. |
Technical Advantages Screws
- High torque transmission capacity and outstanding torsional strength through heat-treated shafts.
- Process flexibility through interchangeable elements, allowing optimisation of mixing, shear and venting performance.
- Selection of advanced PM steels for maximum abrasion resistance (high vanadium content) and corrosion resistance (high chromium content).
Limits & Capabilities
- Co-rotating twin-screw assemblies are manufactured without standard dimensional limitations and are fully customised according to machine design.
