Coperion’s revised version of the Kombiplast KP compounding system has been developed with considerably improved performance.
The system is now more compact and energy efficient than its predecessor and the newer model achieves an even better product quality at an even higher throughput rate.
The Kombiplast features gentle compounding of heat and shear sensitive plastics. This two-stage compounding system comprises a ZSK twin screw extruder equipped with a ZS-B twin screw side feeder and an ES-A downstream single screw discharge unit which gently builds up sufficient pressure for the subsequent pelletising operation in the EGR eccentric pelletiser.
Through its search for a compounding system for PVC, the Italian fittings manufacturer Formatura Iniezione Polimeri S.p.A. (FIP) was impressed by the performance of the Kombiplast. The first unit of the new, improved series – a KP 62 Mv PLUS/200 – has already been put into operation the FIP facility in Casella, Italy. Featuring a screw diameter of 62mm, the extrusion system at FIP is being used for the compounding of tailor-made rigid PVC compounds at a throughput rate of up to 1,600 kg/hour. The PVC compound is then injection-moulded into valves for pip system fittings. FIP’s core competence is the production of high-quality fittings for piping technology, especially valves and other moulded parts, in such thermoplastics as PVC-U, PVC-C, PP-H, and PVDF.
An important innovation featured in the Kombiplast is Coperion's patented Feed Enhancement Technology (FET), which is incorporated in the ZS-B twin screw side feeder. The feeding zone is provided with a porous, gas-permeable wall section which a vacuum is applied externally, permitting extraction of the air between the particles and hence considerably improving the material intake capacity in the processing of feed limited products, such as dry blends. This improvement to feed behaviour has a positive effect on operating reliability and hence on the production rate and the quality of the compound.
Another part of the system that has undergone fundamental improvement is the ES-A single-screw discharge unit, the cylindrical barrel is now cooled with water instead of with a cooling fan. The result is a reduction in electricity consumption and an improvement in the accuracy with which the temperature profile can be set and controlled. The ES-A is now driven by a geared motor, thus permitting a reduction in the height of the machine base. Consequently, the new Kombiplast is more compact, more clearly arranged and so consequently takes up less space than its predecessor. For better pelletising performance, both the drive and the rotor bearings of the EGR eccentric pelletiser have been improved: the knives can be set more accurately, thus ensuring a consistently uniform length of chopped pellet.
Coperion’s Kombiplast offers a great many advantages when it comes to the compounding of heat and shear sensitive polymers. These advantages range from the short and definable residence time profile of the material in the extruder process section to the rapid and easy cleaning of the system and the ready adaptation of the system to new tasks. Typical areas of application are the stable, energy-efficient compounding of flexible and rigid PVC, the production of special-purpose compounds such as halogen-free, self-extinguishing formulations for cables (HFFR) or elastomer based compounds for the production of low, medium and high voltage cables.
