Extrusion International 1-2024

40 Extrusion International 1/2024 MEASUREMENT TECHNOLOGY Inline Thickness Measurement as a Success Factor in Plastic Film and Sheet Extrusion Rising energy and raw material prices, issues related to personnel recruitment, and increased customer quality and traceability demands pose significant challenges for most extrusion operations in their daily production routines. The quality of products is defined, among other factors, by uniform properties across the width (flatness with tight thickness tolerances) and surface quality (free from defects). H owever, the efficient operation of an extrusion line is made possible by the interaction of numerous factors, as well as the design and condition of the equip- ment components. Notably, the influence of the operat - ing personnel also plays a crucial role. Inline thickness measurement is thus a vital quality verification tool for equipment operators and QC personnel. Inline Thickness Measurement Inline thickness gauges primarily provide quality con- trol visibility during ongoing production by continu- ously displaying the cross-sheet thickness profile of the produced film or sheet. This provides immediate recom - mendations to the operating personnel for achieving the tightest possible product tolerances and minimal raw material usage. Since the operating personnel have other tasks be- sides constantly monitoring the thickness profile, inter - vention typically occurs only when the gauge raises an alarm. Alternatively, with the option of Automatic Pro- file Control (APC), in conjunction with automatic dies, these systems automatically regulate the thickness pro- file deviation ensuring it stays within preset control lim - its, thereby ensuring a flat thickness profile of the films/ sheets. This aids in producing consistent, high-quality product with minimal waste and faster startups and product changes. Moreover, thickness-optimized films enhance the effi - ciency of subsequent processing. The setup process, for example, in thermoforming systems and their produc- tion speed, depends significantly on the thickness pro - file of the film. The same applies to printing, converting, and other processing methods and refinements. Visualization Picture 1 exemplifies the visualization of a thickness gauge HMI. The upper portion displays the thickness profile, and below it is a bolt status diagram, correlated with the lip adjustment bolts on the flat die. It is funda - mental to optimize raw material usage during produc- tion and ensure the quality and usability of the product at all processing steps. The operating personnel can immediately identify, based on the bolt diagram, which bolts need adjust- ment to maintain the required tolerances. This is es- pecially valuable during startup and material/product KAPA – measuring frame