MACHINERY | SCREWS AND BARRELS
success. For example, they can solve issues with feed limitation or quality problems due to the shorter residence time by increasing the mixing capability,” he says.
Above: Entek says its screw design software means better optimisation to the specific application
great value to our customers,” says Linda Camp- bell, Director of Sales at the company. “We want them to see first-hand how it can make their lives easier by giving them the ability to specify, and provide a drawing of, exactly what they need for their applications.” Meanwhile, Markus Schmudde, Head of
Research & Development at Coperion, identifies two main trends he sees driving developments in compounding extruder screws and barrels. Firstly, new construction materials are providing custom- ers with more efficient solutions, not only for standard processes but also for special applica- tions. Secondly, new screw geometries are being introduced that can provide better product quality and/or more efficient operating conditions. “Every year, plastics producers are creating new
Right: KraussMaffei Berstorff’s 72HA lining is claimed to cut wear rates
materials or new formulations to improve their products,” Schmudde says. “As a machine vendor Coperion needs to meet the require- ments for these new products in terms of quality and cost effectiveness in production. This means that we either have to develop new screw configurations for better mixing capabili- ties or we need to use new materials of constructions to provide a reasonable lifetime for Coperion parts.” Schmudde says that requirements can be very
different depending on the customer and their compounding project. “Customers producing masterbatch or specialities focus on downtime of the machine during product changes. Other customers try to utilise the machine as much as possible by increasing the throughput to its limits. This positively affects, for example, the energy consumption of the process. For high throughputs, new or modified screw elements can be critical for
68 COMPOUNDING WORLD | August 2018
Material trends The material of construction of screw and barrel parts is also of interest when machines are utilised at or near their production limits. “The mechanical stress to barrels and screw elements increases significantly with higher throughput and motor power of the machine. The specific torque of twin screw extruders was significantly increased a couple of years ago by all machine vendors in the world market, following Coperion’s introduction of ZSK Mc18
technology. Providing materials of construction with high lifetime and high robustness for a variety of processes is a task which is still ongoing,” says Schmudde. Coperion’s latest development in the screw and
barrel area is its Involute screw elements, intro- duced in 2017. “With these elements we are able to increase the throughput for filled compounds significantly and utilise the machine more efficient- ly. However, new screw or barrel geometries are not always the perfect solution. Standard elements that have been on the market for a long time still have a lot of potential if used in a meaningful combination with other elements,” says Schmudde. “Coperion is aware that other vendors, selling mainly single elements, are very active in devel- oping new geometries,” he says. “Our philosophy is that we use our experience in designing complete screw configurations to meet customers’ requirements. We use and develop new screw elements only if we see a significant improve- ment with these parts. Otherwise, we use existing technologies which are well known by our custom- ers. Another important key
factor is that we also focus on providing or developing one universal
screw design for our customers’ product portfolio to reduce downtime and increase the profitability of their production.”
Targeting wear Last year, KraussMaffei Berstorff introduced a new highly wear resistant liner option for its ZE BluePower extruder models. The company said the move was a response to the higher demands
www.compoundingworld.com
PHOTO: ENTEK
PHOTO: KRAUSSMAFFEI BERSTORFF
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