The Gneuss Processing Unit (GPU) has been available for several years now and has proven itself for the reprocessing of bulky PET waste such as post-consumer bottle flake and industrial waste from fiber and film manufacture without pre-drying. A Gneuss Processing Unit consists of a Gneuss MRS extruder with its unmatched devolatilization and decontamination performance in combination with a highly-efficient Gneuss Rotary Filtration System and an online viscometer VIS for intelligent dynamic viscosity control.
Although originally developed specifically for PET, the MRS is now also running in polyolefin and nylon applications, and being tested on a range of other materials and applications. Thanks to the patented combination of single screw extruder with a multiple screw section, the extruder is very sturdy and particularly well suited for recycling applications. The MRS extruder permits the processing of PET without pre-drying by using a simple water ring vacuum system to process the material directly to high quality end products. This is achieved by means of its unique and patented processing section. Based on a conventional single screw extruder, the Multi Rotation Section is a drum containing eight satellite single screws, driven by a ring gear and pinion transmission. The “barrels” cut into the drum are approximately 30 % open and provide optimum exposure of the melt.
Thanks to this design, the devolatilizing performance is approx. fifty times greater than that of a conventional single screw extruder - and this at a vacuum of only 25 to 40 mbar. By avoiding the need for a deep vacuum system and pre-drying, the MRS is an economically efficient alternative to conventional technologies. Further arguments in its favour besides energy savings are the simple and rugged design, small footprint, its ease of operation and low maintenance, processing flexibility and last but not least its excellent melt quality and homogeneity.
One area this technology has been especially successful is in PET sheet extrusion. Besides producing high quality rigid sheet, Gneuss now also offers the option for its PET sheet extrusion lines to quickly and flexibly switch to producing physically foamed PET sheet with the addition of Gneuss’ new PET foam module. Foam sheet with a weight reduction of 50 % can be extruded (depending on the process) with a consistent foam structure and mechanical properties. And this from up to 100 % post-consumer material. Foamed PET sheet is an ideal material for economically manufacturing thermoformed containers for the food industry such as meat trays, egg cartons, cups or plates.
The patented Rotary Filtration Systems are characterized by the filter disk on which the screen cavities are located in a ring pattern and which is completely encapsulated by the two filter blocks. Screens can be inserted into the cavities by opening a small hatch door giving access to the cavities while the production process continues to run without any interruptions or disturbances. All models have been completely revised in the last years. Modifications to the screen changer housings permit operation on a wider range of applications at higher pressures, whilst offering enlarged active filtration areas. Components and modules have been commonised in order to offer shorter delivery lead times and lower costs.
The SFXmagnus series operates automatically as well as process and pressure constant. It is suitable for a very wide range of applications. This series is characterized by an extra large active screen surface area, its compact design, as well as extremely easy operation. Screen changes do not have any influence on the product quality. Gneuss’ top model, the RSFgenius, operates with an integrated self cleaning system for very demanding applications and highest quality requirements. Screens can be automatically re-used up to 400 times and filtration finenesses below 10 microns/1200 mesh are available. The KF range of continuous filtration systems is designed specifically for applications with frequent material type, grade or color changes as well as for high pressure applications like blown film. The KF screen changers are especially compact and offer excellent value for money while permitting simple and quick screen changes on the fly.
As a machinery manufacturer, Gneuss has the manufacturing capabilities to realize even unusual sensor requirements. The lean manufacturing structure at Gneuss makes this possible with shortest delivery times. Gneuss sensors are available to match regional or application - specific requirements such as Atex, Hart Communication or EAC. In especially difficult process conditions with short pressure overloads, frequent pressure spikes as well as unmelts in the material, sensors are highly stressed. Gneuss builds a special heavy-duty design with a special membrane technology for these applications. Also, Gneuss offers a special transducer for food applications, where regular cleaning of the machinery is necessary, so that sensors are often subject to steam or water jets. Gneuss has developed a special type of sensor for these applications, which remains waterproof even if its plug is removed.
Source: MacPlas (www.macplas.it)
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