TECHNOLOGY | MACHINERY SCREWS
Barrier screw solves problem of rejects on pipe extrusion line
A new Xaloy barrier/mixing screw, designed by Nordson, has helped a pipe extruder to solve a long-standing series of production problems. A production line at US-based pipe manufac- turer Polyethylene Technol- ogy was exhibiting wide fluctuations in throughput caused by surging and – for heavy-wall HDPE pipe – consistently exhibited variation from the target wall thickness of 0.097in (2.46 mm). “We tried all sorts of solutions,” said Brad Williams, senior manufac- turing manager. “We looked for problems with
TWIN-SCREW EXTRUSION
Conical extruders add an edge to production
Egger, an Austrian-owned manufac- turer of edge strips – which are mainly used in furniture – is using conical twin-screw extruders from Battenfeld- Cincinnati in its Turkish operations. Egger Dekor, based in Gebze in
Turkey, is using several ConEx NG 65 models. Egger is mainly a wood processing company but uses the machines to make edge strips from ABS and PVC. “In addition to ABS and PVC, which
we process in roughly equal quanti- ties, we make a small amount of special strips from PMMA,” said Ender Celebi, technical plant manager. “Our edge strips are sold in some 70 countries worldwide.”
44 PIPE & PROFILE EXTRUSION | April 2020
While ABS strips are more in demand in Western and Central Europe, PVC strips are common in Eastern Europe and North America.
Egger Dekor installed its
first ConEx NG 65 in 2017. Some existing components designed by the customer were connected to the extruder to form a complete line. When choosing the new extruders, it was important for all raw materials to be processed on the same extrusion lines. “Together with the customer, we
processed several compounds at our technical lab in Vienna, to demonstrate the performance of our new conical extruders,” said André Wieczorek,
solved by using the Xaloy Efficient barrier screw with a Nano mixer in the metering section. Brad Casale, Nordson
the motor drive and the puller, tested four or five dif- ferent resins, and finally got a new screw and relined barrel – all with no success. Our gravimetric extrusion control showed fluctuations occurring every five or 10 seconds.”
Another problem was poor mixing of carbon black, where an addition level of 2% was required. “We couldn’t get a good
mix, and there were always areas of the pipe with too little carbon black,” he said. The problems were
regional sales manager, said: “By preventing premature break-up of solids and increasing melting rates, the screw enhanced mixing and increased throughput on the line. The Nano mixer provided intensive mixing of the carbon black.” As well as solving the
surging problem, and delivering a homogeneous melt, the new screw in- creased the output of the line by around 12%. �
www.nordson.com
CTO of Battenfeld-Cincinnati. A long preheating zone and an optimised screw design ensure a balanced ratio of mechanical and thermal energy input, so different materials can be processed, and tool pressures of up to 520 bar applied. �
www.battenfeld-cincinnati.com
www.pipeandprofile.com
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