MACHINERY | ALTERNATIVE COMPOUNDERS
system in a gas-fired variant with conventional electrical cartridge heating. It says it showed that the initial investment in the liquid system is higher but the operating costs can be amortised after less than one year and the cost of the complete extrusion system after three-and-a-half years. This is attributed to the more efficient transfer of heat to the product, which the company claims can reduce the heating requirement by up to 50%. In addition to the energy saving, Entex says that
Above: Ram-Stuffer single screw extruders are being used in direct WPC processing installations
According to Farrel Pomini, the study found the CP550 successfully replicated the earlier results of very good molecular weight retention. At a 60% filler level, molecular weight retention was 98% when using a small amount of processing additive. A throughput rate of 450 kg/h was achieved and within the nominal production range for this model, however, the company says it believes higher production rates can be realised. It said the results demonstrate that its continuous mixers can produce PLA filled masterbatch at viable produc- tion rates in a commercial setting.
Triple benefits Chinese company Cowin Extrusion offers a triple-screw extruder that it claims retains many properties of a traditional twin screw extruder, but extends that to include some additional character- istics such as improved plasticising and mixing. The arrangement of a triple screw is also said to ensure a good self-cleaning effect. According to Cowin, compared to a traditional
Right: Entex says the good thermal regulation of its planetary roller extrusion technology makes it well suited to processing of sensitive materials
twin-screw extruder, the screw meshing area on its triple-screw design is doubled and this consider- ably improves mixing. The length to diameter ratio of the screws is shorter, while the residence and mixing time of material is longer. Output rates are also higher as the triple-screw machine offers 50% more capacity than a twin-screw extruder. A 20-40% energy saving is also claimed. Applications are said to include highly filled compounds, colour and functional masterbatching, and reactive extrusion. Planetary roller extruder maker Entex Rust and
Mitschke claims that one of the key benefits of its machine design is in the improved thermal control it offers through its combination of liquid-based cooling technology and thinner wall thicknesses. This can be especially advantageous when pro- cessing thermally sensitive materials such as PVC. The company recently undertook a study that compared its liquid-based thermal regulation
34 COMPOUNDING WORLD | October 2021
www.compoundingworld.com
the ‘settling in’ process is about five times faster than using electrically temperature-controlled systems and processes can also be effectively cooled more quickly. The Ram-Stuffer single screw extruder from
Davis-Standard is said to be able to handle anything from light bulk density fluff to shredded flakes, including materials with varied bulk densities. That makes it well suited to the reprocessing of film scraps, but systems are also being used in applica- tions such as chemical recycling of mixed plastics and direct processing of wood-plastics composite (WPC) materials, according to the company. The Ram-Stuffer uses a pneumatically actuated plunger to force material into the extruder, with the feed section of the barrel using a grooved technol- ogy to enhance conveying of the material. Davis- Standard says it offers a reduced upfront and operational cost compared to alternatives such as twin screw extruders.
CLICK ON THE LINKS FOR MORE INFORMATION: �
https://www.linkedin.com/in/hans-ulrich-siegenthaler �
www.busscorp.com �
www.farrel-pomini.com �
www.cowinextrusion.cn �
www.entex.de �
www.davis-standard.com
IMAGE: DAVIS-STANDARD
IMAGE: ENTEX RUST AND MITSCHKE
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