EXTRUDER TECHNOLOGY | MACHINERY
TwinEx 93-34 parallel twin screw extruder to make highly filled PVC pipe. The extruder was fitted with a gravimetric dosing unit for processing up to 100 parts of chalk without premixing. High proportions of filler chalk can make PVC pipes cheaper, by reducing the need for polymer. A basic PVC formulation and filler material were fed separately to the production line. Individual components were then put together in a collection hopper and blended in a cold mixer. After mixing, the finished formulation was passed to the feed opening of the extruder via a vertical dosing unit. The extruder served as processing unit for the
PVC formulation. The processing unit has a specially adapted screw geometry with anti-wear protection to transport and plasticise the blend evenly. The varying chalk content – ranging from 30 to 100 parts – can easily be adjusted to the correct formulation needed for the product. A further benefit of direct gravimetric chalk dosing is process stability, which ensures a high-quality end product. Finally, the process eliminates the need for premixing of PVC and chalk in a heating/cooling mixer. The arrangement seen at the show allows solid
PVC pipes with filler content to be produced using a mono-layer pipe die. For three-layer pipes with a filled middle layer and external layers without filler content, the company offers appropriate pipe dies and conical co-extruders. In this way, pipes up to 400mm in diameter can be produced economically. The company also showed a new small version
of its SolEx NG. The model completes its high- speed extruder series for pipe extrusion. The 45mm version adds to the existing sizes of 60, 75, 90 and 120mm. The series features a combination of internally grooved barrels with matching special screw geometry. Advantages of this include: up to 40% higher outputs; about 10°C lower melt temperatures; and 15% less energy consumption. When processing HDPE, the extruders achieve 25% higher output – and up to 40% for PP, it said.
At K2022, Battenfeld-Cincinnati also launched its
Steady flow software module, which minimises pulsation in PVC extrusion – leading to even, continuous output. In PVC processing with counter-rotating twin
screw extruders, pulsations of the material flow are caused by C-shaped chamber profiles formed by the pair of screws. The new module harmonises these fluctuations for constant material discharge. Melt pressure in front of the extrusion die is
measured continuously, and screw speed during each screw rotation is constantly re-adjusted on the basis of the pressure fluctuations. The software includes a learning function, which automatically calculates optimal parameters for the compensation of pulsation during the first production run with any new products or new materials, says the company.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.coda-products.com �
www.davis-standard.com �
www.tecnomaticsrl.net �
www.plastonline.org �
https://www.bausano.com �
www.battenfeld-cincinnati.com
Above: Tecnomatic’s Evo range of extruders feature a redesigned feed screw
IMAGE: TECNOMATIC
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