MACHINERY | TWIN SCREW EXTRUDERS
the handling of these units during cleaning and maintenance, including a fast connection mecha- nism to mount the barrels. The ZS-EG is now fitted with radial shaft sealing rings and, as a result, the lantern area remains visible. They additionally permit nitrogen purging in an explosive environ- ment. “Thanks to the new seals, there is no longer a vacuum present in the gear lanterns, and the service life of the gear-side shaft seal is consider- ably longer,” Schmudde says. The new features are already available for the 58mm version of Coperion’s side degassing and side feeder units. All other sizes – from 40mm to 92mm – will become available this summer.
Flexible operation KraussMaffei Berstorff points to several new highlights on its ZE BluePower series, including the highly flexible processing section, safe torque transmission, and optimum wear protection. The company says the modular range of barrel sections with 4D and 6D lengths – equipped with C-clamp system for rapid and safe replacement – together with the wide variety of screw elements, ensure “uncompromising flexibility” when configuring customised solutions for specific applications. “The combination of increased free volume in the process- ing section and higher torque gives optimum conditions for cost-effective compounding,” the company says. Improved side feeders and a variety of feed-port stuffers help ensure high output rates. Tooth profiles of screw shafts and screw ele- ments have also been optimised, as has the screw preloading system and the geometry of the connecting sleeves, to make sure high torque levels are safely transmitted. The company says a number of other technical improvements implemented in the ZE BluePower series “provide increased availability and unparalleled ease of maintenance in 24/7 production mode.” For example, new wear liners complement its range of induction hardened or powder-coated barrel sections to achieve effective wear protection for all applications.
Right: KraussMaffei Berstorff’s ZE BluePower machines are designed for flexible production and maximum uptime
Right: The new ZS-EG side degassing unit from Coperion is initially available in a 58mm version
Downstream integration Development of a “melt com- pounding engine” for PVC is the first of many development initia- tives started over the last year at Steer with the aim of commercialising a twin-screw extruder with improved capabilities, according to Managing Director & Chief Knowledge Officer Dr Babu Padmanabhan. He says this melt compounding engine provides very precise control over specific mechanical energy input. “PVC processing is extremely sensitive to the point at which complete fusion occurs,” he notes. Rigid PVC pipe and profile production normally employs counter-rotating screws to minimise shear and avoid degradation. “Counter-rotating screws offers minimal shear but more importantly a strong elongation flow at the nip zone to achieve fusion,” Padmanabhan says. “The problem is that the specific throughput is low, resulting in a large residence time distribution. With our Fractional Geometry Technol- ogy, we were able to achieve the elongational flow requirements with much higher specific throughput rates, reducing the residence time as well as providing better control over stability.” Knowing that Sheer’s co-rotating extrusion technology can achieve better dispersion and distribution of glass fibre with PVC while minimising shear and attrition, Padmanabhan says the com- pany began a series of experiments with patented wave elements and other fractional geometry technology-based advanced screw designs. “Fractional geometry technology of Steer will also pave the way for production of normal PVC pipes, with associated benefits of high output, less stabiliser level and reduction in
PHOTO: KRAUSSMAFFEI BERSTORFF 26 COMPOUNDING WORLD | March 2018
replacement costs of screws,” he claims. Reinforced PVC pipes obtained using the melt engine exhibited superior mechanical properties – tensile and flexural strength,
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PHOTO: COPERION
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