Processing quality management
Firstly Film thickness can be measured using a variety of non-contact methods. X-rays or infrared to measure the overall film thickness and also to measure the layer thickness in multi-layer films. Secondly it is also possible to use mass measurement as an indicator of film thickness.
Thirdly, shrinkage will affect extruded products just as it does any plastic product and needs to be considered in any product dimensional measurement.
Example : adjustment and measurement of film thickness can be carried out by adjusting either the haul-off speed or the die lips and this can be automatic or manual.
Moreover, film requires not only control of variations in the machine direction but also in the transverse direction.
Most importantly, changes in factory conditions can have a large effect on extruded products. Cause and effect, the temperature changes due to draughts from open doors, because it is an ‘open’ process.
Extrusion needs good environmental controls for consistent products.
Effect of the Thickness on the Film Morphology
Film thickness plays a key role on the final surface morphology since the close interaction with the substrate can enhance, for instance, the phase separation compared to the bulk. Several works have explained the structures formed in terms of chain conformations that directly depend on the film thickness. Other studies have evidenced that the polymer-air interface is deformed due to the influence of the surface tension on the boundary shape.
And, in other cases the type of structure remains constant independent of the film thickness, but the dimensions of the phase-separated domains decreases for thinner films.
In conclusion, SCANTECH do the thickness measurement with a full range of sensors, gauges, control systems, servers and input/outputs. And for all types of line designed for the thickness measurement and appearance control.
SOme text from : Robin Kent, in Quality Management in Plastics Processing, 2016