Application
Soft-Touch SEBS & TPE Overmolding Compound Underwater Pelletizing Line
High-oil extended SEBS /…
Solution
Closed-Loop Underwater Pelletizing and Chilled-Water System for Thermoplastic Elastomers
Closed-loop underwater pelletizing and precision chilled-water system for soft TPE, TPU, EVA, and hot-melt adhesives, eliminating die smearing and pellet agglomeration.
- Solution scope
- Multi-Function System
- Flow and installation
- Continuous · Inline
- Capacity
- 150–2000 kg/h
This solution establishes a specialized closed-loop underwater pelletizing and process water thermal management system engineered specifically for thermoplastic elastomers (TPE, TPU, TPV), polyolefin elastomers (POE), high-VA ethylene-vinyl acetate (EVA), and hot-melt pressure-sensitive adhesives. Integrating an enclosed underwater cutting chamber (Underwater Pelletizer), high-pressure bypass water piping, an inline centrifugal dewatering spin dryer (Underwater Pelletizing Dehydrator), and a dedicated closed-loop industrial refrigeration chiller (Industrial Chiller), it delivers instantaneous surface freezing and precision cutting for polymers that cannot be processed via traditional strand or water-ring cutting.
Soft elastomers with low Shore hardness (< 85A), low melting points, or high tackiness present notorious processing challenges. When cut via strand pelletizers, elastomeric strands stretch like elastic rubber bands, break unevenly, wrap around feed rollers, or stick together in the cooling bath. In water-ring die-face systems, hot tacky melt smears across the die plate and fuses onto cutting blades, triggering catastrophic line shutdowns. By immersing high-speed rotating cutter blades directly against a thermally isolated die plate within a high-velocity chilled-water stream, this solution instantly freezes molten droplets into perfectly uniform micro-spheres or mini-pellets, preventing agglomeration and strand snapping.
The problem
What the section changes
Eliminates strand stretching and die smearing for soft TPE, TPU, and hot-melt adhesives, producing spherical non-stick pellets.
Where the customer starts
Compounders attempting to produce soft TPE/TPU/EVA on traditional strand lines suffer continuous production halts. Strands neck down, stretch, and break inside the water bath, requiring manual re-threading by operators every 15 minutes, which exposes operators to hot melt splash hazards.
If switched to water-ring pelletizers, the tacky melt adheres to the hot die plate, wrapping blades into a fused molten blob (“hockey puck”) that instantly jams the drive motor. The resulting downtime, cutter regrinding, and barrel purgings create massive scrap losses and severely cap plant productivity.
Why the problem happens
Soft elastomers and hot-melt resins have extremely low elastic modulus and high surface tackiness in the semi-molten state. In open air or standard water troughs, the cooling rate is slow and non-uniform, allowing hot polymer cores to transfer heat to the surface, causing strands to stick together or stretch irreversibly.
Moreover, on a die face, if water flow is insufficient or water temperature fluctuates by even 2°C–3°C, the die holes either “freeze off” (polymer solidifies inside the die hole, blocking flow) or “smear” (molten polymer wraps around the blade). Maintaining a high-velocity, temperature-controlled water blanket directly over the cutting face is the only method to achieve instantaneous droplet skin freezing.
Target output or state
Flawless, non-stick, perfectly spherical elastomer micro-pellets with zero die-face smearing, low surface moisture (≤ 0.05%), and uninterrupted 24/7 extrusion run times.
Process
The steps, in the order the material flows
The equipment named here is maintained on the step it belongs to, so the list and the quotation cannot disagree.
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Continuous Melt Pressurization & Delivery
RequiredExtrusion and Melt Processing
Delivers a stable, surge-free, and precisely pressurized molten elastomer stream to the underwater die plate.
Role of the equipmentCo-rotating twin-screw extruder plasticizes and devolatilizes the elastomeric blend, discharging through a melt gear pump to ensure pulseless melt feed to the underwater die.
Equipment Twin Screw Pelletizer
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Submerged Die-Face Micro-Cutting
RequiredPelletizing
Cuts molten polymer droplets in a high-velocity chilled water blanket, instantly freezing the pellet outer surface into a spherical geometry.
Role of the equipmentThe cutter head rotates at 1,500–4,500 RPM with pneumatic blade pressure against the thermally insulated die plate. Chilled water flowing through the chamber carries frozen pellets away within milliseconds, preventing die wrap.
Equipment Underwater Pelletizer
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Closed-Loop Chilled Water Thermal Management
RequiredCooling
Continuously extracts process heat from the recirculating water loop, maintaining precise water temperature (±0.5°C) to prevent die freeze or pellet stickiness.
Role of the equipmentDedicated industrial refrigeration chiller circulates 8°C–18°C water through a plate heat exchanger, ensuring stable cooling capacity regardless of summer factory temperatures.
Equipment Industrial Chiller
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Centrifugal Slurry Separation & Drying
RequiredPost-Pellet Treatment
Separates pellets from the high-volume water slurry, expels surface moisture, and discharges dry, cooled elastomer pellets.
Role of the equipmentPellet-water slurry flows into the centrifugal dehydrator. High-g centrifugal acceleration removes 99.9% of surface water through the screen basket, discharging dry pellets at < 38°C.
Equipment Underwater Pelletizing Dehydrator
Material
What goes in, what comes out
Feed condition and requirements
Molten thermoplastic elastomer or polymer melt pumped through a melt gear pump or twin-screw extruder at melt pressures up to 15–25 MPa and melt temperatures of 150°C to 240°C. Resins: TPU, TPE, TPV, POE, EVA (VA up to 40%), SIS, SBS, hot melt adhesives.
Output condition and boundaries
Highly uniform, spherical micro-pellets or standard granules (Ø1.2 mm to Ø3.0 mm) with smooth, defect-free outer skin. Residual surface moisture ≤ 0.05% (500 ppm), exit pellet temperature ≤ 38°C, zero doublets or stringers. Pellets flow freely without blocking or clumping in storage bags.
150–2000 kg/h
Basis for the capacity figures
Based on continuous underwater cutting linked to a co-rotating twin-screw extruder compounding line, with pelletizing throughput capacity from 150 kg/h up to 2,000 kg/h, producing uniform spherical pellets Ø1.8 mm to Ø3.2 mm.
Fit
Where this section belongs — and where it does not
The boundaries are part of the solution: they keep a machine from being quoted into a case it cannot serve.
Suitable when
Indispensable for compounders producing soft thermoplastic elastomers (TPU, TPE, TPV, TPR) with hardness between Shore 30A and Shore 85A where strand cutting is impossible.
Essential for packaging and hygiene adhesive manufacturers pelletizing low-softening-point hot-melt adhesives (EVA / POE / SIS) into non-blocking spherical beads.
Not suitable when
Not suitable for rigid, brittle thermoplastics with high crystallinity and high melting points (e.g., PPS, PEEK, unplasticized PVC) where low-cost strand pelletizing or air-cooled die-face cutting is far more economical.
Not suitable for un-melted solid plastic scrap or regrind flakes; must receive fully homogenized melt stream from an extruder.
Conditions still to be confirmed
Specifications assume thermoplastic elastomer or adhesive grades with Shore hardness between 30A and 95A, melt index between 0.5 and 50 g/10 min, and processing melt temperatures between 150°C and 230°C.
For ultra-tacky, low-viscosity hot-melt adhesives (EVA / metallocene POE with ring-and-ball softening points < 85°C), process water must be treated with food-grade anti-sticking liquid surfactant dosing, and a plate heat exchanger with glycol chiller circuit (operating water down to 5°C–8°C) must be configured.
Site and connections
What the section assumes around it
Utilities
- Power supply
- 380 V / 415 V / 460 V, 50/60 Hz, 3-phase AC.
- Water
- Initial closed-loop water charge: approx. 800–1,500 L softened/demineralized water; makeup consumption: < 50 L/day.
- Compressed air
- 0.6–0.7 MPa dry, clean compressed air for pneumatic cutter blade positioning and water bypass diverter valve (approx. 0.2 m³/min).
- Exhaust and ventilation
- Spin dryer top mist exhaust duct DN100 vented outside to discharge humid vapor.
Total connected electrical power: 30 kW to 90 kW (including cutter motor, water pump, spin dryer, and chiller compressor).
Site constraints
- Footprint
- Skid-mounted compact layout: approximately 12–18 m² for cutter carriage, water tank skid, chiller, and dryer.
- Headroom
- Clear vertical ceiling height of 3.5 m to 4.2 m.
- Environment
- Clean industrial manufacturing workshop; ambient temperature 5°C to 40°C; indoor placement for chiller and control skid.
Closed-loop water skid eliminates shop-floor water spills and open gutter trenches.
Interfaces
- Mechanical
- Precision machined diverter valve flange connecting melt pump to die plate; DN80 / DN100 stainless sanitary water pipes.
- Control
- High-speed Ethernet/IP or Profinet link to upstream extruder PLC; automated safety handshake halts extruder feed instantly upon water flow fault.
- Upstream and downstream
- Upstream: melt gear pump / continuous screen changer. Downstream: vibrating cooling classifier or pneumatic pellet blower.
Targets
What the section is judged on
The numbers are targets agreed per project, not a general promise.
- Pellet Doublets and Agglomerates Rate
- 0.00% % Manual optical count on 1,000 random pellets sampled from exit chute
- Process Water Temperature Stability
- ± 0.5 °C Continuous PLC digital data logging of water supply temperature
- Discharged Pellet Surface Moisture
- ≤ 0.05% (500 ppm) % Halogen moisture balance testing at 105°C for 10 min
How acceptance is judged
Continuous commissioning trial run of 4 hours at maximum rated capacity on the customer’s soft elastomer formulation (e.g., Shore 50A–70A TPE or TPU). Pellets must show 0.00% doublets/triplets (agglomerates) and zero thermal smearing or wrap-around on the die face.
Process water temperature entering the cutting chamber must be maintained within ±1.0°C of the target setpoint (typically 12°C–18°C) under full extruder load. Discharged dried pellets must have residual surface moisture ≤ 0.05% with packaging temperature ≤ 38°C without pellet-to-pellet blocking inside containers.
Scope of supply
What is in the delivery — and what is not
The confirmed scope is stated in the quotation; this is the boundary of the section as designed.
Included in the scope of supply
- Underwater Pelletizer Cutting Chamber Skid Thermally isolated die plate with carbide wear ring, hydraulic advance/retract carriage, pneumatic cutter blade auto-tensioning, and variable-speed cutter drive.
- Process Water Loop Skid with Pneumatic Diverter Valve SUS304 process water tank, high-volume stainless centrifugal pump, automated 3-way water bypass diverter valve, and cartridge filter housing.
- Integrated High-Efficiency Centrifugal Spin Dryer Stainless steel centrifugal dewaterer with hardened rotor tips, easy-clean screen basket, inspection window, and exhaust fan.
- Dedicated Industrial Process Water Chiller Skid High-COP scroll compressor, compact brazed plate evaporator, digital PID temperature controller, and dual circulating pumps.
- Master PLC Automated Interlocking System Siemens S7-1200 / 1500 PLC with touchscreen, one-button start/stop sequencing with automated water-bypass flush to prevent die freeze.
Not included in the scope of supply
- Compounding twin-screw extruder and loss-in-weight feeders Upstream extruder, barrel heaters, gravimetric feeders, and side stuffers belong to the extruder contract.
- Primary cooling tower water circuit to chiller condenser Cooling tower piping to the water-cooled chiller package is customer scope.
- Anti-tack liquid chemical consumables Supply of anti-blocking agents or surfactant chemicals for adhesive pelletizing is customer scope.
- Finished product packaging scale and bag sealer Downstream packaging line and palletizing robots unless explicitly quoted.
Before a price
What we confirm before this becomes a quotation
- 01 Polymer chemistry and rheology data sheet Resin type (TPU ether/ester, SBS, SEBS, TPV, EVA), Shore A/D hardness, melt flow index (MFI), and melt temperature curve.
- 02 Target pellet dimensions and throughput rate Nominal pellet diameter (e.g., standard 2.5 mm or micro-pellet 1.2–1.5 mm) and target continuous output (kg/h).
- 03 Available factory plant cooling water conditions Inlet temperature and flow of primary cooling water loop supplying the chiller condenser (e.g., 30°C–32°C tower water).
- 04 Extruder flange interface dimensions Melt pipe diameter, bolt circle pattern, and heating zone control specs of the upstream extruder or melt gear pump.
Request a Quote Send these points with your inquiry; the section can then be quoted against your line, not against an assumption.
Photos
The section in the workshop
Photos go here once the section has been built and the material is cleared to publish.
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Placeholder · 1200 × 900 px (4:3)（占位图） Replace with an approved section photos, real workshop or installation views at this size.（按此尺寸替换为正式图片。） -
Placeholder · 1200 × 900 px (4:3)（占位图） Replace with an approved section photos, real workshop or installation views at this size.（按此尺寸替换为正式图片。）
Details
Further details
- Main production problem
- Insufficient cooling
- Line output limited by auxiliaries
- Sticking and agglomeration