Compounding of high performance engineering plastics

Compounding of high performance…
The German company Ensinger GmbH has placed an order with Coperion GmbH, Stuttgart/Germany, formerly Werner & Pfleiderer, for a twin screw extruder of the new ZSK Mc18 series.

The compounder is equipped with 45 mm diameter screws, two ZS-B side feeders and one ZS-EG twin screw side devolatilization unit. Ensinger is specialized in the production of compounds, semi-finished products, profiles and finished products in high performance engineering plastics and will be using the new compounder at its main factory at Nufringen/Germany for the production of high-grade compounds reinforced, for example, with glass or carbon fibres. Typical matrix materials are polyamide (PA), polyether ether ketone (PEEK) or polyethylene terephthalate (PET).

The ordered ZSK 45 Mc18 is a high-temperature version capable of approximately 50% higher heating capacity, which means that the required high processing temperatures of more than 350 °C – especially for the processing of PEEK – can be reliably achieved and maintained with absolute precision.

Ensinger’s decision in favour of the ZSK 45 Mc18 was based on many years’ positive experience with several ZSK compounding extruders of similar sizes.

The decisive factors for the present requirement were the processing advantages offered by the ZSK Mc18, especially the improved temperature control in the extruder process section. The cooling channels, which surround the process section in each barrel, run at right angles to the direction of material flow, giving not only a high cooling capacity but also a very homogeneous cooling of the process section.

Compounding of high performance engineering plastics

As with previous models, each barrel of the process section is temperature-controlled separately, a feature that is particularly advantageous for processing. Unlike external heating shells cartridge heaters generate heat directly inside the process section – exactly where it is needed.

The wear-resistant oval liners are shrink-fitted (hence gapless) into the extruder barrels for optimum thermal transfer, making the heat exchange between the material in the barrel and the respective extruder section faster and more efficient. For the installation of ZS-B side feeders and ZS-EG twin screw side devolatilization units, the ZSK Mc18 series is equipped with combi barrels that are also fitted with cooling channels, thus permitting optimum temperature control.

ZSK Mc18 twin screw extruders are generally distinguished by their particularly energy-saving mode of operation, the decisive factor being – besides the improved temperature control – the reduced input of specific energy into the product by reason of the higher torque, the higher throughput rate and the new, user-friendly thermal barrel covers.

The ZSK 45 Mc18 for Ensinger has been rated for flexible application with a very wide spectrum of different compounds. This gives Ensinger the assurance of also being equipped for any new or changed market requirements in the future. The process section of the ZSK 45 Mc18 is equipped with two ZS-B side feeders and a ZS-EG twin screw side devolatilization unit.

The ZS-B side feeders permit the feeding of fillers and additives at the points most favourable for the process. One of the ZS-B side feeders is equipped with the patent pending Feed Enhancement Technology (FET) for the feeding of high-volume fillers and additives with low bulk density, typical examples being talc and hollow glass beads.

With this technology, the entrained air is drawn off with the aid of a gas permeable wall, permitting an increase of up to three times the throughput rate. With its large free cross section, the ZS-EG side devolatilization unit ensures efficient degassing, even in cases where the gas content is high. It keeps the melt reliably in the process section during operation without product leakage.


Double screw extruders and compounding systems manufacturer