Coperion has redesigned the EGR eccentric pelletizer for operation with the two-stage Kombiplast compounding system. The scope of changes covered the overall system design, air supply, material conveying and pellet handling. According to the company, the new version of the unit provides clearly improved pellet quality, particularly when processing temperature- and shear-sensitive plastics. At the same time, energy consumption in the pelletizing system has been reduced. The manufacturer also points to simplified operation. Faster heating of the system and more efficient product changeovers, including die plate replacement, are expected to translate into higher overall equipment effectiveness, OEE, for the complete line. The EGR pelletizer is integrated with the two-stage Kombiplast system, which Coperion designs for the production of soft PVC, rigid PVC and HFFR formulations.
Processing and pelletizing temperature- and shear-sensitive plastics is one of the more demanding tasks in compounding. In such applications, the material should be handled as gently as possible throughout the entire process in order to maintain consistently high pellet quality. Based on simulations and practical trials, Coperion optimized the air supply system in the EGR pelletizer. As a result, pellet conveying now takes place at significantly lower feed pressure, which reduces stress on the material. The company states that this conveying method improves product quality and at the same time reduces the risk of agglomerate formation. The changes also have economic and environmental implications. Compared with the previous EGR version, energy consumption for material conveying has been reduced by up to 75%, which means lower operating costs and a reduced CO2 footprint.
Higher system availability
Coperion has also redesigned the die plate heating system so that it can now be easily separated from the die plate itself. Assembly and disassembly of the die plate are now significantly faster, which is particularly important during recipe changes. At the same time, the pelletizer itself can be heated in a shorter time, reducing production downtime. According to the company, these changes have increased the uptime of both the EGR pelletizer and the entire compounding system, which translates into a higher OEE figure.
Simplified operation and service
In the new EGR version, operation of the unit has also been simplified. During die plate replacement, operator safety has been improved. A split, pivoting pelletizer hood facilitates access to the blade, allowing faster and more precise adjustment of the pelletizing knives and thereby improving cut quality. The optimized design is also intended to simplify maintenance and service work, shortening the time required for routine operations and helping to reduce unplanned downtime.
Another important change is the relocation of the EGR drive to the front of the pelletizer hood. This arrangement makes it easier to install a screen pack changer between the Kombiplast discharge and the EGR pelletizer, which is often required in the production of cable compounds.
Kombiplast and EGR in one system
The two-stage Kombiplast compounder combined with the EGR eccentric pelletizer is intended as a solution tailored to the production of temperature- and shear-sensitive plastics such as PVC or cable compounds. Coperion indicates that the system has been designed for the gentlest possible product handling throughout the entire compounding process, while maintaining high economic efficiency and process flexibility.
Raw materials are first fed into the process section of the ZSK twin-screw extruder by means of a ZS-B twin-screw side feeder, where conveying, plasticizing, mixing and homogenization take place. In the ZSK Mv14 version, with an increased torque of 14 Nm/cm³, the extruder is intended to ensure particularly gentle product processing while achieving high throughput. Product discharge takes place via the ES-A single screw, which builds up the pressure required for the EGR eccentric pelletizer.
At the pelletizing stage, the EGR cuts cylindrical strands of material exiting the die plate into uniform pellets using rotating pelletizing knives. The pellets are then removed by pressure conveying with the aid of new inflatable seals. The pelletizing knives are mounted on a blade positioned eccentrically relative to the die plate. The blade speed can be adjusted continuously. Coperion adapts the number, diameter and geometry of the die plate holes to the material properties and the user's individual requirements.
The redesigned Coperion EGR eccentric pelletizing system delivers higher compound quality and significant energy savings in the production of temperature- and shear-sensitive plastics
