Water Ring Cutting Waste Plastic Recycling and Granulating Line

Overview

The Water Ring Cutting Waste Plastic Recycling and Granulating Line is an integrated agglomerator-plus-single-screw extrusion system purpose-built for converting low-bulk-density post-consumer and post-industrial polyolefin waste into high-quality recycled pellets. By combining a specially designed agglomerator that transforms fluffy film (bulk density 0.05–0.15 g/cm³) into dense, free-flowing feedstock (≥ 0.30 g/cm³) with a high-torque single-screw extruder, this line processes PE bags, printed LDPE film, agricultural film, raffia (woven PP bags), foamed EPS, and PP/PE flakes — materials that would starve a conventional single-screw due to poor feeding. The water ring cutting system delivers near-spherical, non-agglomerating pellets. With throughputs from 250 to 550 kg/h across three models, it serves recycling operations, compounders, and vertically integrated manufacturers seeking to close the loop on flexible polyolefin waste. See our complete range of plastic pelletizer machines for alternative configurations.

Technical Parameters

Capacities measured with washed PE film regrind (moisture < 8%, bulk density ≥ 0.30 g/cm³ post-agglomeration); actual throughput varies by material type, contamination level, and moisture content.

System Configuration

Core Features

1. Agglomerator Pre-Densification — Solving the Film Feeding Problem

Loose PE film has a bulk density of merely 0.05–0.15 g/cm³ and will not gravity-feed reliably into a standard single-screw hopper. The specially designed agglomerator uses frictional heat (120–150 °C) generated between a rotating blade assembly and a stationary knife ring to cut, shrink, and densify the film in a single continuous step. Post-agglomeration bulk density increases to 0.30–0.45 g/cm³, raising screw fill ratio from below 30% to over 80% . This directly translates the extruder's installed motor power into throughput rather than wasting energy on a starved, partially filled screw — the fundamental reason this line achieves 250–550 kg/h on film waste where a standalone single-screw of equivalent size might manage only 80–120 kg/h.

2. Water Ring Cutting for Near-Spherical, Non-Stick Pellets

Melt exiting the die plate is cut immediately by rotating blades and quenched in a water ring that surrounds the die face. This simultaneous cutting-and-cooling mechanism produces near-spherical pellets that solidify before contacting each other, effectively eliminating agglomeration — a common problem with strand pelletizing of low-melt-strength recycled PE. Pellet sphericity improves bulk density in downstream handling, reduces dust generation during pneumatic conveying, and ensures uniform feeding into injection molding or film-blowing processes. Blade RPM is closed-loop synchronized with extruder screw speed via the PLC to maintain pellet size consistency across the full throughput range.

3. Broad Polyolefin Feedstock Compatibility

The agglomerator-extruder combination handles materials that span the full range of polyolefin waste types and morphologies. Proven feedstocks include: post-consumer PE grocery bags, heavily printed LDPE shrink film, film on rolls loose bundled, agricultural greenhouse and mulch film, woven PP raffia sacks, foamed EPS (expanded polystyrene), and washed PP/PE flakes. The system's flexibility means recyclers can pivot between feedstock streams as market availability shifts, avoiding single-stream dependency. For operations processing rigid scrap alongside film, Chenxing offers integrated shredder-extruder recycling solutions for a complete front-end size-reduction stage.

4. Non-Stop Filtration with Hydraulic Screen Changer

Contaminants — sand, paper labels, degraded gel particles, ink residues — are inevitable in post-consumer polyolefin waste. The hydraulic slide-plate screen changer performs full mesh swaps in under 30 seconds without interrupting extrusion. Melt pressure is maintained throughout the changeover cycle via dual-seal design (metal-to-metal primary + polymer backup). When the upstream pressure transducer detects a threshold pressure drop indicating screen clogging, the operator triggers the change; the line continues extruding while the fouled screen is replaced offline. For heavily printed film (ink load > 3%), a coarser 40–60 mesh specification is standard; cleaner post-industrial scrap runs efficiently with 80–120 mesh.

5. Continuous Automated Production from Feedstock to Bagged Pellet

The entire process — agglomerator densification, single-screw plastication, melt filtration, water ring cutting, centrifugal drying, and vibrating classification — runs as a single continuous stream without intermediate batch steps. Pellets exit the vibrating screen and discharge directly into the automatic weighing and bagging station. A pellet vacuum loader can be integrated between the silo and packing station for dust-free automated transfer, or a vacuum conveyor loader for connection to downstream blending equipment such as a plastic heating mixer. Operator intervention is limited to feedstock replenishment, screen-change triggering, and filled-bag removal.

6. Flexible Downstream Configuration by Material Type

Because different waste streams impose different post-cutting requirements, the line supports configurable downstream modules. High-moisture feedstocks (e.g., washed film flake with > 10% surface moisture) benefit from an extended centrifugal dryer section and optional hopper dryer pre-conditioning. Lightweight foamed materials (EPS) require a larger-volume agglomerator hopper and extended residence time in the cutting chamber. Abrasive raffia may justify a higher-specification nitrided screw with bimetallic barrel upgrade. The electrical control cabinet supports recipe-based parameter sets (agglomerator RPM, extruder zone temperatures, cutter speed) that operators can recall per feedstock type. Browse our auxiliary machines catalog for optional modules.

Production Process

Step 1 — Feedstock Loading: Waste PE film, bags, raffia, or PP/PE flakes are loaded into the agglomerator feed hopper — either manually, by conveyor belt, or via a force-feeding auger for continuous operation. A hopper dryer is recommended upstream for moisture-sensitive or washed feedstock.

Step 2 — Frictional Densification in Agglomerator: The rotating blade assembly spins at high speed against a stationary knife ring inside the agglomerator chamber. Frictional heat rapidly raises the material temperature to 120–150 °C — below the melting point of PE/PP — causing film to shrink, partially fuse, and fragment into dense, irregular crumbs. Bulk density jumps from 0.05–0.15 g/cm³ to 0.30–0.45 g/cm³, transforming unfeedable film into a compacted granular feedstock that gravity-feeds reliably into the extruder throat.

Step 3 — Melt Plastication in Single-Screw Extruder: Densified material enters the SJ-P series single-screw extruder. Multi-zone barrel heating (typically 160–230 °C for LDPE/LLDPE, higher for HDPE/PP) and screw shear progressively melt and homogenize the polymer. The nitrided screw with an optimized L/D ratio for recycled feedstock ensures complete plastication without excessive residence time that could degrade heat-sensitive materials.

Step 4 — Melt Filtration: Homogenized melt passes through the hydraulic screen changer, where contaminants — gels, paper residues, unmelted particles — are captured on the filter mesh. The operator swaps screens on the pressure-drop signal without pausing production. Filtered melt then enters the die head at stable pressure for consistent pellet formation.

Step 5 — Water Ring Cutting & Pellet Transport: Melt exits the die plate as strands that are immediately cut by rotating blades. The surrounding water ring quenches and transports the freshly cut pellets, preventing inter-pellet sticking. Water temperature is maintained via a closed-loop cooling circuit with optional SML series chiller for high-ambient-temperature environments.

Step 6 — Dewatering, Classification & Packing: Pellets enter the centrifugal dryer where high-speed rotation removes surface water to a residual moisture content of typically ≤ 0.5% . The vibrating screen then classifies pellets, removing oversize and fines. In-spec pellets discharge into the automatic weighing and bagging station (standard 25 kg bags) or an optional big-bag filling system.

Frequently Asked Questions

Q1: How does the agglomerator convert low-bulk-density film into feedable material, and what prevents premature melting?

The agglomerator operates on frictional heat generated between a high-speed rotating blade assembly and a stationary knife ring — the material heats to 120–150 °C without external heating elements. This temperature sits strategically below the crystalline melting point of LDPE (≈105–115 °C) and HDPE (≈130–135 °C), meaning the film shrinks, softens, and fragments through thermo-mechanical stress rather than undergoing full melt-phase transition. The knife clearance (typically 0.3–0.5 mm) is calibrated to cut and densify rather than smear. As film is shredded and compacted, bulk density rises from 0.05–0.15 g/cm³ to 0.30–0.45 g/cm³ — a 3–6x improvement — transforming a material that would bridge and starve in a standard hopper into a free-flowing granular feedstock. The densified output exits via a discharge port directly above the extruder feed throat, maintaining continuous gravity flow. If material temperature approaches the melting threshold, the PLC reduces agglomerator RPM or triggers a cooling-zone water spray to prevent fusion inside the chamber. This mechanical densification principle is what fundamentally enables this line's film-to-pellet throughput advantage over conventional single-screw recycling extruders.

Q2: Water ring cutting vs. strand pelletizing vs. hot die-face cutting — which is optimal for PE film recycling and why?

For PE film recycling, water ring cutting offers the best balance of pellet quality, operational simplicity, and throughput among the three methods. Strand pelletizing — where extruded strands travel through a water bath before cutting — struggles with low-melt-strength recycled PE, which tends to snap during strand pulling, causing frequent line stoppages. Hot die-face cutting (air-cooled) works well with rigid formulations like PVC but generates higher pellet surface temperatures that can cause recycled PE pellets to stick and agglomerate before adequate cooling. Water ring cutting solves both problems: the water ring quenches pellets instantly at the die face, preventing stickiness without requiring strand integrity. Pellet sphericity from water ring cutting is typically superior to strand-cut cylinders, improving bulk density and downstream feeding. The water also functions as a transport medium, moving pellets directly to the centrifugal dryer — eliminating the need for pneumatic conveying or long water-bath runs. The tradeoff is managing a water circuit (filtration, temperature control, make-up water), but for recyclers processing 250–550 kg/h of PE film, the productivity gain over strand systems typically justifies this infrastructure within the first year of operation.

Q3: Can heavily printed LDPE film be processed directly, and how does ink affect pellet quality?

Yes, heavily printed LDPE film (ink coverage > 80%, multi-color flexographic prints) can be processed directly without de-inking, and the majority of ink is captured by the hydraulic screen changer rather than remaining in the pellets. During plastication at 160–230 °C, ink pigments and binder resins partially decompose into fine particulate and volatile fractions. The volatile fraction exits through the barrel degassing vent; the particulate fraction is caught by the filter mesh. With a standard 80-mesh screen, most pigment agglomerates above approximately 180 µm are retained. The resulting pellets typically exhibit a slightly grayish or tinted base color — not pure translucent — with residual ink content below approximately 0.05–0.1 wt% under optimized filtration. This grade is fully acceptable for black or dark-colored film blowing, garbage bag production, and injection molding of non-aesthetic components. For applications requiring lighter pellet color, operators can: (a) step down to 120-mesh filtration (with more frequent screen changes), (b) increase the degassing vacuum level to draw more volatiles, or (c) blend printed and unprinted scrap at a controlled ratio. The agglomerator's pre-densification step is particularly beneficial here — it distributes ink pigments uniformly into the polymer matrix rather than concentrating them in hot spots that could cause die-lip buildup during extrusion.

Q4: What pellet moisture content can be expected after centrifugal drying, and is additional drying needed?

After the centrifugal dryer, residual surface moisture content is typically ≤ 0.5 wt% under standard operating conditions (ambient 20–25 °C cooling water, dryer RPM at nominal setpoint). This level is sufficient for most immediate reuse scenarios — bagging, storage, or direct feeding into injection molding and film blowing — without a secondary drying step. However, three factors can push moisture higher: (a) elevated cooling-water temperature (> 30 °C) in tropical or summer environments, which raises pellet temperature entering the dryer and reduces evaporation rate; (b) excessive throughput beyond the dryer's rated capacity, reducing residence time in the centrifugal basket; and (c) porous or micro-porous pellet surfaces from degraded or highly contaminated feedstock that trap water in surface cavities. For these scenarios, residual moisture may reach 0.8–1.2 wt% . An optional SML series chiller on the water circuit maintains cooling water at a consistent 15–20 °C, which reliably brings moisture below 0.3 wt% even in high-ambient conditions. For extrusion-grade applications (film blowing, pipe, profile), moisture below 0.5 wt% is industry-acceptable; for injection molding requiring < 0.1 wt%, a downstream hopper dryer should be added. Chenxing offers integrated dryer modules as part of the downstream configuration for customers with stringent moisture specifications.

Q5: What is the energy consumption per ton (kWh/kg) and how does the agglomerator contribute to overall line efficiency?

Total specific energy consumption for the water ring cutting pelletizing line ranges from approximately 0.42 to 0.55 kWh/kg (420–550 kWh per metric ton of finished pellet), with the exact figure depending on model size, feedstock type, and operating throughput. This breaks down roughly as: agglomerator drive 25–30% (0.11–0.15 kWh/kg), extruder main drive 45–55% (0.20–0.28 kWh/kg), barrel/die heaters 10–15% (0.05–0.07 kWh/kg), and auxiliaries (cutter, dryer, screen changer, blower) 10–15% (0.05–0.07 kWh/kg). The SJ150P operating at its midpoint of 350 kg/h on washed PE film typically draws approximately 0.45–0.48 kWh/kg. At first glance the agglomerator appears to add 25–30% to the energy bill. However, this must be evaluated against what a standalone high-output single-screw extruder achieves on film without pre-densification: a starved screw operating at 30% fill ratio wastes 60–70% of its installed power on frictional heat in the partially empty barrel rather than on conveying and melting material. The agglomerator's energy investment enables the extruder to operate at 80–90% fill — effectively doubling or tripling specific throughput per installed kW. The net result is that total specific energy (agglomerator + extruder combined) is comparable to or lower than a standalone extruder processing film, while achieving 2–3x the output. All main drive motors are IE3 premium efficiency as standard, and the PLC's recipe-based parameter management minimizes energy waste by loading optimized RPM and temperature setpoints per feedstock type.

Why Choose Chenxing

Proven Agglomerator + Single-Screw Architecture. The agglomerator-extruder combination has been deployed in recycling facilities across multiple continents, processing everything from heavily contaminated post-consumer PE bag waste to clean post-industrial LDPE film trim. Each line is factory-tested with customer-supplied feedstock samples before shipment, validating throughput, pellet quality, and energy consumption against agreed specifications.

Integrated Ecosystem. Chenxing manufactures the complete upstream and downstream equipment chain — from shredder-extruder recycling systems for front-end size reduction and plastic heating mixers for masterbatch blending, through to hopper dryers for moisture control, vacuum conveyor loaders, chillers, and pipe coilers. A single-source supplier dramatically simplifies commissioning, operator training, service coordination, and spare parts procurement. Browse our complete product catalog and auxiliary machines section.

Recycling-First Design Philosophy. Unlike general-purpose pelletizers retrofitted for recycling, this line was engineered from the ground up around the physical realities of waste polyolefin feedstock: low bulk density, variable contamination, inconsistent moisture, and broad particle morphology. The agglomerator is not an add-on — it is the core differentiator that makes film-to-pellet continuous processing economically viable at industrial scale.

Engineered-to-Order Flexibility. Agglomerator knife configuration, extruder screw geometry (compression ratio, mixing element placement), screen changer mesh specification, dryer capacity, and control system features are configured per order — not selected from a fixed catalog of three options. Visit our solutions page for application-specific configuration examples and case studies.

Global Support. Chenxing Machinery, headquartered in Zhangjiagang City, provides remote commissioning guidance via video link, on-site technician dispatch for installation and start-up, operator training (on-site or at our factory), and lifetime technical support including troubleshooting and spare parts supply. Learn more about us and keep up with the latest news and application notes.

Start Your Inquiry in 4 Steps

Step 1 — Describe Your Feedstock: Tell us your waste stream — material type (PE film, PP raffia, EPS foam, or mixed), physical form (loose bags, bales, rolls, washed flakes), estimated contamination level, and typical moisture content. Photos or a short video of your feedstock are highly valuable.

Step 2 — Define Your Output Target: Specify your desired throughput in kg/h, preferred model range (SJ120P, SJ150P, or SJ180P), pellet application (film blowing, injection molding, pipe extrusion, or resale), and any pellet quality specifications (color, moisture, size).

Step 3 — Receive a Tailored Proposal: Our engineering team evaluates your feedstock characteristics and output requirements, then provides a custom configuration — agglomerator sizing, screw design, screen changer mesh spec, and all downstream module recommendations — typically within 24 hours of receiving complete information.

Step 4 — Validate with a Trial Run: Optionally, send 50–100 kg of your actual waste feedstock to our Zhangjiagang factory for a trial production run. We return pellet samples with a detailed report covering throughput achieved, energy consumption, pellet moisture content, and visual quality assessment — giving you hard data to support your investment decision.

Contact Nicole directly:

• Phone WeChat WhatsApp: +8615951187228

• Email: ceo@cxsljx.com

Or visit our contact page for the full inquiry form. We respond to all inquiries within one business day.