Advanced Air-Cooled Die-Face Pelletizing Technology

In modern plastics processing, the quality of the final pellet is strongly influenced by the stability of the melt, the geometry of the die openings, cutting conditions and the cooling process immediately after pellet formation. EXTRUTEX has developed its air-cooling die-face pelletizing systems around these critical processing requirements.

Instead of transporting freshly cut pellets through a conventional water bath, the air-cooled configuration uses controlled airflow to remove heat from the newly formed pellets. The cutting process takes place directly at the die face, allowing the polymer strands to be divided into compact pellets immediately after exiting the extrusion die.

This configuration is particularly attractive for compounding applications where a clean and efficient pelletizing process is required. The absence of a conventional water-cooling section can reduce water consumption, eliminate the need for extensive pellet dewatering and simplify the overall plant layout.

EXTRUTEX systems are designed for demanding industrial production environments and can be configured according to the polymer, filler, additive package, required throughput and final pellet characteristics. The extrusion section can also be selected according to the formulation, including single-screw, co-kneader or co-rotating twin-screw processing technology.

Complete Pelletizing System from EXTRUTEX

An air-cooled die-face pelletizing line is more than an extrusion machine with a cutter. Consistent production requires every stage of the process to operate together. EXTRUTEX therefore supplies the pelletizing system as an integrated production solution, with the main equipment sections coordinated for stable continuous operation.

1. Feeding and Material Preparation

Depending on the formulation, the raw materials may include virgin polymers, recycled polymers, mineral fillers, pigments, flame-retardant additives, starch-based components or other functional ingredients. Accurate feeding is essential when producing masterbatch and highly filled compounds.

Gravimetric or volumetric feeding equipment can be selected according to the application. Multiple feeders can be integrated when several powders, granules or additives must be introduced independently into the process. Proper feeding control helps maintain formulation consistency and stable melt quality throughout the production run.

2. Extrusion and Compounding

The extrusion section is responsible for melting, conveying, dispersing and homogenizing the formulation. EXTRUTEX can engineer the processing section around the characteristics of the material being processed.

For demanding compounding applications, a co-rotating twin-screw extruder can provide intensive distributive and dispersive mixing. For applications requiring gentler processing or different residence-time characteristics, alternative extrusion technologies can be considered.

The screw configuration, barrel arrangement, L/D ratio, heating and cooling zones, venting and filtration system can all be selected according to the formulation. This allows the same general pelletizing concept to be adapted for different polymer families and production requirements.

3. Melt Filtration

A melt filtration unit can be installed between the compounding section and the pelletizing die when the formulation or raw material requires removal of contaminants. This is especially useful when processing recycled polymers or formulations containing solid impurities.

Depending on the application, EXTRUTEX can configure manual, hydraulic or continuous screen-changing filtration solutions. The filtration arrangement is selected according to melt pressure, contamination level, polymer type and required production capacity.

4. Die-Face Pelletizing

After the polymer reaches a homogeneous molten condition, it is conveyed toward the pelletizing die. The die plate contains precisely manufactured openings through which the melt exits in controlled quantities.

A rotating cutter operates directly against the die face and divides the emerging melt into individual pellets. Cutter speed, die temperature, melt pressure and extrusion output are coordinated to achieve stable pellet dimensions.

This direct cutting principle eliminates the long strand-cooling path used in conventional strand pelletizing. It also provides a compact production arrangement that can be particularly useful where factory floor space is limited.

5. Air Cooling

Immediately after cutting, the hot pellets enter the controlled air cooling section. High-volume airflow removes thermal energy from the pellet surface while the pellets are transported toward the collection system.

Air temperature, airflow volume and residence time can be adapted to the material and production conditions. Correct cooling control is important because insufficient cooling can result in pellet agglomeration, while excessive or poorly controlled cooling can affect pellet transport and product consistency.

6. Conveying and Screening

After cooling, the pellets are transferred through the conveying system toward a screening or classification section. Screening can separate oversized or undersized particles and return them to the production process when required.

The finished material can then be collected in bags, big bags, silos or automatic packaging systems depending on the production environment.

Designed for Polymer Compounding and Masterbatch Production

The EXTRUTEX air-cooling die-face pelletizing system can be configured for a wide range of polymer modification processes. The equipment is particularly suitable for formulations where mineral fillers, pigments, functional additives or recycled components must be distributed evenly throughout the polymer matrix.

The final configuration is determined by the formulation, polymer viscosity, filler loading, required throughput, pellet dimensions and thermal sensitivity of the material.

Major Applications

Filled Polymer Compounds

Filled polymer compounds are produced by combining thermoplastics with mineral or functional fillers to achieve specific mechanical, economic or processing characteristics. EXTRUTEX pelletizing lines can be used for formulations based on materials such as PVC, PE and EVA combined with calcium carbonate, talc, titanium dioxide and carbon black.

Calcium carbonate is widely used as a cost-effective mineral filler, while talc can contribute to stiffness and dimensional stability. Titanium dioxide is commonly incorporated where high opacity and whiteness are required, and carbon black can provide coloration and selected functional properties.

Degradable and Biodegradable Masterbatch

Masterbatch production may involve combining polymers such as PE or PS with starch-based materials, processing aids and other functional additives. The extrusion system must provide sufficient mixing to distribute the additives throughout the polymer while maintaining appropriate thermal and mechanical processing conditions.

EXTRUTEX can engineer the feeding, mixing, venting and pelletizing sections according to the formulation and desired masterbatch concentration.

Flame-Retardant Masterbatch

Flame-retardant formulations require controlled additive dispersion and careful thermal management. Materials such as PE and EVA can be combined with selected flame-retardant additives to produce concentrated masterbatch products for subsequent dilution during plastics processing.

The EXTRUTEX compounding section can be configured with suitable screw elements, feeding systems, temperature control and venting to accommodate the characteristics of the formulation.

Suitable Materials

Why Use Air-Cooling Die-Face Pelletizing?

One of the primary advantages of air-cooled die-face pelletizing is the simplified cooling process. Conventional water-ring or strand systems require water circulation, cooling equipment and, in many cases, additional pellet drying equipment. An air-based system can reduce the number of auxiliary processes required around the pelletizer.

• Reduced dependence on process cooling water.
• No conventional water bath required for pellet cooling.
• Direct cutting at the die face.
• Compact equipment arrangement.
• Reduced pellet drying requirements.
• Suitable for continuous industrial production.
• Adaptable to different polymer formulations.
• Integrated conveying and screening options.
• Flexible extrusion technology selection.
• Designed for masterbatch and filled-compound production.

EXTRUTEX Engineering and Manufacturing

EXTRUTEX supplies polymer processing equipment based on Austrian design principles and engineering standards, with manufacturing operations in Nanjing and Shanghai, China. This combination provides customers with European-oriented engineering development together with competitive industrial manufacturing capability.

Our engineering approach focuses on the complete production process rather than treating the pelletizer as an isolated machine. The feeding system, extrusion technology, screw configuration, filtration, die, cutter, air cooling, conveying, screening and control system are selected as parts of one coordinated production line.

Every formulation behaves differently. A calcium-carbonate-filled PE compound does not require exactly the same process configuration as a flame-retardant EVA masterbatch or a PVC-based formulation. For this reason, EXTRUTEX can adapt the equipment configuration according to the customer's material recipe and production objectives.

Technical Configuration

The following specification table represents a typical configuration framework. Exact dimensions, motor power, throughput and pellet size are determined according to the selected extrusion system and material formulation.

Process Control and Automation

Stable pellet production depends on precise control of extrusion temperature, melt pressure, screw speed, cutter speed and cooling conditions. EXTRUTEX control systems bring the principal process parameters together through a centralized operator interface.

Depending on the selected configuration, the PLC system can monitor barrel temperatures, melt pressure, motor load, screw speed, cutter speed, cooling airflow and other critical operating parameters. Alarms and interlocks can be incorporated to improve operational safety and protect the equipment during abnormal conditions.

Automated control also makes it easier for operators to reproduce established processing recipes when producing different grades of masterbatch or compound.

Flexible Extrusion Options

EXTRUTEX does not restrict the air-cooled die-face pelletizer to one extrusion technology. Depending on the material and formulation, the extrusion unit can be selected from different processing concepts.

Single-Screw Extruder

A single-screw extruder can be used for relatively straightforward melting, conveying and blending applications where the formulation does not require intensive distributive or dispersive mixing.

Co-Kneader

A co-kneader can be considered for formulations requiring controlled, relatively low-shear processing and effective incorporation of fillers and additives.

Co-Rotating Twin-Screw Extruder

A co-rotating twin-screw extruder is particularly suitable for complex compounding operations requiring strong mixing performance, multiple material feeding points, devolatilization and flexible screw configuration.

The extrusion technology is therefore selected according to the actual formulation instead of forcing every product through one standard machine configuration.

Production Advantages for Masterbatch Manufacturers

Masterbatch producers often need to manufacture multiple formulations using the same production platform. A modular EXTRUTEX pelletizing line can be configured to provide the flexibility required for different recipes and production capacities.

The air-cooling principle can also simplify factory utilities because the process does not depend on a conventional water bath for the main pellet cooling stage. This can be valuable in facilities where water treatment, recycling and drying systems would otherwise increase the complexity of the installation.

The final result is a compact and configurable pelletizing platform suitable for compounders, masterbatch manufacturers, polymer modifiers, additive producers and recycling-related applications.

Customized Pelletizing Lines

EXTRUTEX can engineer the complete line around the customer's production target. Important design parameters include polymer type, formulation, filler percentage, additive loading, melt temperature, required throughput, pellet dimensions, feeding method and packaging arrangement.

Optional equipment can include automatic feeding systems, loss-in-weight feeders, vacuum loaders, melt pumps, continuous screen changers, vacuum degassing, die systems, automatic cutter assemblies, air cooling conveyors, pellet classifiers and automatic packaging equipment.

This modular approach allows the same engineering platform to serve both specialized laboratory-scale development projects and demanding industrial production lines, with the final configuration determined by the required output and material characteristics.

Typical Application Summary

EXTRUTEX: Austrian Design, Chinese Manufacturing

EXTRUTEX combines Austrian-oriented engineering and machine design with industrial manufacturing capabilities in China. Our production network in Nanjing and Shanghai enables the manufacture of complete polymer processing equipment and supporting systems while maintaining a strong focus on engineering customization.

For international customers, this approach creates a practical balance between engineering quality, manufacturing efficiency, customization and project cost. From the initial material evaluation through machine configuration, production and commissioning, EXTRUTEX can provide a complete technical solution for polymer pelletizing and compounding.