Revised Compounding System is More Energy Efficient

The Kombiplast KP compounding system from Coperion, Stuttgart, Germany, is now available in a revised version with improved performance.

More compact and more energy-efficient than its predecessor, this new model achieves better product quality at a 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 that gently builds up sufficient pressure for the subsequent pelletizing operation in the EGR eccentric pelletizer.

In its search for a compounding system for PVC, the Italian fittings manufacturer Formatura Iniezione Polimeri S.p.A. (FIP) was very 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 at the FIP facility in Casella, Italy. Featuring a screw diameter of 62 mm, the extrusion system at FIP is being used for the compounding of tailor-made rigid PVC compounds at a throughput rate of up to 1600 kg/hr. The PVC compound is then injection-molded into valves for pipe system fittings. FIP's core competence is the production of high-quality fittings for piping technology, especially valves and other molded 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. There the feeding zone is provided with a porous, gas-permeable wall section to which a vacuum is applied externally, permitting extraction of the air between the particles, considerably improving the material intake capacity in the processing of feed limited products, such as dry blends. This improvement to feed behavior has a positive effect on operating reliability, as well as 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 takes up less space than its predecessor. For better pelletizing performance, both the drive and the rotor bearings of the EGR eccentric pelletizer have been improved: the knives can be set more accurately, thus ensuring a consistently uniform length of chopped pellet.  

The new Coperion Kombiplast KP produces tailor-made rigid PVC compounds at a production rate of up to 2000 kg/hr.

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