Extrusion International 4-2020

35 Extrusion International 4/2020 Gamma Meccanica S.p.A. Via Sacco e Vanzetti, 13, 42021 Bibbiano (RE), Italy www.gamma-meccanica.it need is to recycle heavily printed and contaminated post-consumer PE waste obtaining granules with spe- cific technical characteristics to be used in the pipe pro- duction. This GM180 Tandem Plus is the result of increas- ingly advanced research by technical staff of Gamma Meccanica and the collaboration of selected partners in the industry. The first part of the line consists of COMPAC ® feeding system and a single-screw extruder with a diameter of 180 Ø. Connected to the first extruder is a self-cleaning screen changer installed to remove the contaminants present in the melted polymer. The patented Gamma Meccanica high performance vacuum system is in- stalled at the exit of the screen changer andallows for removal of up to 10 times more gas and humidity in the melted material compared to other systems. The high performance vacuum chamber is connected to a second co-rotating twin-screw extruder, with 90 mm screw diameter, 44:1 L/D ratio, two standard degas- sing sections, two lateral inlets for mineral fillers and additives and a dosing section for liquids. The fillers and additives are fed into a gravimetric dosing system. At the end of the twin-screw extruder is installed our TDA water ring pelletizer developed and produced by Gamma Meccanica which, in addition to guaranteeing high production performance, makes cleaning opera- tions simple and quick during the changes of produc- tion and startup of the system. The regeneration and “upcycling” process begins with 9 gravimetric dosing stations to feed the materials in a more precise and accurate way to the COMPAC ® system which has the function of shredding and densifying the waste material to be recycled. From the COMPAC ® unit, the material is pushed with constant flow from the feed- ing screw into the extruder. The melt obtained during the extrusion phase is filtered by the automatic screen changer which removes even the smallest particles of contaminants (down to 80 micron). At the exit of the screen changer, the melt is “degassed” by the high performance vacuum chamber to avoid de- fects in the granules such as “air bubbles”. At this point, the polymer is “enriched” with master, carbonate and various additives inside the twin-screw extruder. The fill- ers and additives are introduced by the dosing system which guarantees maximum precision. The upcycling process ends with the cutting of the melted material in- side the TDA pelletizing system. Installed on the system is an inline measurement of the viscosity and the Gamma UPC digital scale control for the real - time measurement of the productivity and energy consumption of the unit. This complete system has an average production capac- ity of 1300 kg/hr of enriched PE compound. This technological solution gives a much higher value to the product from waste with the upcycling process. Much like other solutions developed by Gamma Mec- canica the Tandem Plus allows for contributions to the protection of the environment, both for the type of ap- plication and for better energy savings and minimum environmental impact. Tandem Plus line