Leistritz: New pull-in aid increases throughput of polyolefin fluff six times as much

In the case of materials with low bulk density, the performance of extrusion systems is often limited by the material feed. Due to their low density and particle geometry, such materials can form bridges in the catchment area or float onto the extruder screw. This restricts the material feed, even though the extruder still has available processing capacity.

The new feed assist evenly distributes the material from above onto both extruder screws and breaks up material bridges in the feed zone. In this process, only a slight compaction of the material occurs. According to the company, this approach enables a continuous material flow without exerting additional lateral pressure on the extruder screws. Separate pre-compaction of the raw material can thereby be omitted.

Increased throughput with low bulk density

In an experiment on a twin-screw extruder of the type "ZSE 50 Maxx", Leistritz investigated the processing of polyolefin fluff with a bulk density of 25g/l and particle sizes between 1 and 5 cm. Without additional feed-in aid, the throughput was 40 kg/h. With the "LEH", the processing capacity increased to 240 kg/h. This corresponds to a sixfold increase in throughput, or a 500 percent improvement.

Further tests were conducted with materials having bulk densities of 40 and 75 g/l. In the material with a bulk density of 75g/l, the maximum processing power was no longer limited by the material supply, however by the available torque of the extruder. No specific throughput values were provided to these two test series.

The results demonstrate that, when processing lightweight bulk materials, the material feed can have a significant impact on the usable extruder output. The improved loading makes it possible to make greater consumption of the existing machine capacity, in particular in the case of materials with a low bulk density.

consumption to materials with a bulk density of less than 100 g/l

The feeding aid is designed to materials with bulk densities below 100 g/l. This includes, in particular, lightweight plastic recyclates and other bulky raw materials whose flow and feeding behavior make continuous feeding difficult.

According to Leistritz, particles with dimensions larger than the flight depth of the extruder screws can also be fed. With conventional feeding, such particles can float on the screws, thereby impairing material transport.

The feed-in aid thus starts immediately at the material feed and should enable the processing of low-density starting materials without upstream compaction. No information is available on the energy standards of the device or on its impact on specific processing costs.

Presentation at Fakuma 2026

Leistritz announces that it will demonstrate the feed-in aid at Fakuma 2026 on a twin-screw extruder of the "ZSE 50 Maxx" type. The exhibit will be displayed in Hall A6 at Stand 6302.

Fakuma 2026, Friedrichshafen, 12–16. October 2026, Hall A6, Booth 6302