A process-oriented scale-up/scale-down strategy for industrial blown film processes: Theory and experiments

To gain a competitive edge in developing innovative products, new multi-layer film manufacturers need to know whether laboratory-scale blown film line results reliably translate to large-scale production. This, however, is not always the case: Transferring process conditions and getting equal final film properties are not ensured. To address this problem, this paper presents a scale-independent scale-up/scale-down strategy to produce films with consistently similar properties regardless of a plant’s size and design. A second aim is to prove this strategy is applicable by comparing the reference and experimental film mechanical properties. Here, experimental scale-down runs were carried out based on a process-oriented scale-up/scale-down strategy for the blown film process. An industrial production process (>800 kg/h), successfully transferred to a laboratory-scale blown film line, was used as the reference. The introduced process-oriented scale-up/scale-down is based on geometric and dynamic similarity. In this context, blow-up ratio, draw-down ratio and process time have been identified as major scale-up/scale-down variables. Unlike existing scale-up strategies, the process-oriented approach is more flexible in practice. Film mechanical properties taken from the experimental runs were determined by tensile and puncture resistance tests. The compared results confirmed that process-oriented scale-up/scale-down is feasible for the applied material and under the existing plant-specific restrictions. The comparison indicated that most film properties produced on the laboratory-scale plant were comparable to those from the high-capacity blown film line.