Extrusion International 2-2024

50 Extrusion International 2/2024 Besides the intake and the process sections, also on the discharge end of the compounder, there is potential to optimize for PVC compounding. The aim is to pro- duce a wide range of products on the equipment. This can be achieved using the COMPOE Discharge Pump, a conical twin-screw extruder. A comparison of this discharge pump with a single screw and a melting pump discharge gives insights into the behavior of the various concepts: Single Screw discharging has some disadvantages as it builds up pressure inappropriately with low viscous materials, has insufficient cleaning, and is lacking con - veying capability. Using a melt pump for discharging results in higher shear rates (gear, bearings), lacks long-term stability from abrasive materials, and is sensitive to damages from powder. A discharge pump has the consequence of a higher equipment cost. These costs stand against a series of advantages like high pressure build-up, high conveying efficiency comparable to a gear pump but with gentle conveying without dead zones, no shear peaks, and self-cleaning of the screws. Furthermore, there is an ex- cellent degassing option due to a large surface area. Based on the above and the experience after several trials, it can be concluded that for standard PVC appli- cations, a single screw dis- charge usually is sufficient. A discharge pump is appropriate for special products in the PVC world such as PVC Mas- terbatches. It also can be used for direct extrusion to- gether with dies for pipes, sheets, and so on. To summarize the above: the great flexibility and ca - pabilities of the COMPEO kneader offer major advan- tages in PVC compounding. Optimum quality can be combined with much higher throughputs compared to using traditional set-ups. Complemented with a spe- cially developed discharge pump and the long-standing experience of BUSS in the PVC industry, the COMPEO is ideally suited for solving today's and future PVC com- pounding requirements. The author: Lukas Jenni has an MSc in mechanical engineering and is currently working as a process specialist for BUSS in Pratteln, Switzerland. Buss AG Hohenrainstr. 10, CH-4133 Pratteln, Switzerland https://busscorp.com/ Lukas Jenni COMPEO Discharge Pump First Food Grade R-PET Sheet Production Line to Lithuania By mating its energy efficient sheet extrusion lines with Kreyenborg’s IR-CLEAN Super- Clean process for post-consumer recycled PET, MEAF Machines can now offer its customers a cost effective alternative for the production of FDA/EFSA approved single layer PET food grade sheet. A first R-PET extrusion line combining the two, has recently been installed at Pack Klaipėda UAB in Klaipėda, Lithuania, for the production of meat packaging. The line is also suited for the production of PP trays without alterations, providing the customer with even more flexibility. F ounded some 12 years ago, Pack Klaipėda UAB initially focused on expanded PS containers for take- away food. However, three years ago the company decided to move into other food packaging, notably for meat and poultry. “We looked at several potential suppliers, but found MEAF to have the same out- put at a much smaller footprint than competitors’ offerings,” says Darius Kontrimas, CTO at Pack Klaipėda.