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Two-Stage Compounding System with Innovative Knife Rotor From Coperion
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Source:Coperion    Editor:Coperion    Date:07.Sep.2020

PVC is known for being a robust and abrasion resistant material which can be used for various applications. Not only the construction, health care and automobile industry benefit from the advantageous properties of PVC. Also common household items are frequently made out of this long lasting material since it is easy to clean.

When handling any kind of PVC formulation, gentle processing is key. Only this way too excessive plastification which may even lead to degradation can be avoided. While meeting these quality standards, compounders also seek solutions that are economically efficient and therefore cost effective.

With the Kombiplast KP Coperion offers such system. The two-stage compounding system is especially designed for the production of temperature and shear-sensitive plastics. It can easily be adapted to new requirements and is typically used for plasticized as well as rigid PVC. Furthermore, it is suitable for Peroxide cross linkable PE or Halogen-free, self-extinguishing formulations for cable (HFFR). To provide cable manufacturers with higher flexibility, the Kombiplast is available in a hybrid version. This specific system allows for changeovers between PVC to HFFR processing and vice versa with only a few adjustments. Nonetheless, the general operating principle of the Kombiplast remains the same. The system combines a ZSK twin screw extruder with an ES-A single-screw discharge screw through which gentle pressure build-up is realized. By decoupling the plastification and  homogenization process into two steps excessive pressure is reliably avoided before the PVC material passes the die plate for pelletizing.

Coperion has equipped the Kombiplast’s eccentric pelletizer EGR with a new innovative knife rotor which ensures gentle cutting and avoids the formation of dust. Thanks to this new design, the knives are in even contact with the die plate through which the proportion of fines in the pellets is reduced. This does not only increase the product quality of PVC pellets as such but also prevents pneumatic conveying pipes from accumulating too much dust. As a result, contamination with other products can be avoided and cleaning cycles can be reduced.

To complement the system, Coperion also offers solutions for raw material handling, feeding, dry blend production in the heat-cool mixer, the cooling as well as the packaging of pellets. As a plant and system constructor for the plastics industry, Coperion even designs entire plastics processing plants.

Learn more about the system: https://www.coperion.com/en/products-services/extruders-compounding-machines/kombiplast


The Kombiplast KP combines a ZSK twin screw extruder with an ES-A single-screw discharge screw for a gentle pressure build-up


Kombiplast KP for gentle processing and pelletizing of PVC pellets


The knife rotor reliably avoids the formation of dust (left: PVC pellet cut by previous designs, right: PVC pellet cut with the new knife rotor EGR)



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