SML has announced the launch of the FlexiPET, a new production-scale demonstration line for thermoforming sheet located at SML’s Technology Centre. The co-extrusion sheet line is configured for a classic 3-layer structure (A/B/A), while also offering the flexibility to operate as a 2-layer line (A/B) as required.
The sheet extrusion line incorporates SML’s new twin-screw extruder TSE80 for polyester, a modernised roll stack and the new W650 winder. The development reflects increasing demand within the thermoforming packaging sector for higher recycled-material processing capabilities, energy-efficient extrusion technologies and improved production flexibility.
“At the heart of the line lies the new TSE 80 – a state-of-the-art parallel co-rotating twin-screw extruder designed in-house by SML and specifically optimised for PET,” explains Martin Kastner, R&D Engineer at SML. Equipped with a low-maintenance, water-cooled main drive delivering 348 kW, the TSE 80 achieves an output capacity of up to 1000 kg/h for PET.
According to SML, the TSE 80 is optimised for processing large volumes of materials with low bulk densities, including flakes and regrind. The system is also designed for processing PET/PE flakes, as well as PETG and its post-industrial flake stream (GAG). The compact design and short residence time in the extruder are intended to retain the natural clear colour of PET while preventing yellowing of the film.
To process PET without pre-drying, the TSE 80 is combined with SML’s high-performance vacuum unit. The frequency-controlled two-stage vacuum system combines a roots vacuum pump for high volume flow rates with a dry-running rotary screw pump for low pressure levels, achieving absolute pressure levels as low as 1 mbar.
“A major innovation is the roll stack movement, equipped with servo positioning drives and linear guides, which enables precise, 100 % reproducible positioning in both the horizontal and vertical directions,” Martin Kastner continues.
The FlexiPET line supports PET sheet thicknesses from 150 – 1,400 µm, final net film widths of up to 1,000 mm and total output capacities reaching up to 1,200 kg/h of PET.