BlownUp

Efficient operating point identification by scaling the blown film extrusion process

To counteract the fluctuating material quality of post‑consumer recyclates (PCR) in production, film manufacturers are currently forced to run extensive test campaigns on large‑scale lines to maintain product and process stability, at extremely high cost. It would therefore be highly attractive to identify robust operating windows on smaller laboratory lines instead of on full‑scale production equipment. In the “BlownUp” project, launched in November 2025, IKV is developing a practical scale‑up protocol that enables efficient identification of stable processing conditions for PCR in blown film extrusion.

© IKV

Since laboratory‑ or pilot‑scale processes behave differently from full‑scale production, these discrepancies are first quantified in terms of machine and line settings as well as characteristic film properties. To represent the processing of PCR, model recyclates are produced whose composition reflects that of a typical film packaging structure. A defined degradation state is adjusted by repeated compounding, and the resulting material damage is evaluated on the basis of shear and extensional viscosity measurements.

Trials are conducted on three different line scales. First, two defined film products made from the model recyclate are produced on an industrial line (500 kg/h) at an IKV partner company, recording machine settings and monitoring resulting process parameters. From these data, dimensionless similarity numbers are derived. In parallel, a mini blown film line (4 kg/h) is designed, engineered and built, on which the influence of individual process variables is quantified by means of a statistical design of experiments. The die geometry is determined through a combination of analytical calculations and numerical simulation. Drawing on the first two series of experiments, the most influential figures are identified and used to construct the scale‑up model, which is subsequently validated on a laboratory blown film line with a throughput of 50 kg/h.

Project data and funding

We would like to thank the BMWE for funding the IGF project (funding code 24300 N) and the project partners for their cooperation.

Project duration: 01.11.2025 – 31.10.2027

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