NDC announces a new application capability for its Model 8000 gauging system: a scanning blown film web gauging system designed to measure and control complex, multilayer blown film products. The significance of this measurement configuration is its ability to quickly determine both the profile shape and the average web thickness of both total thickness as well as critical barrier layers. Typically this is accomplished in around four scans (one minute or less) to provide responsive measurement, excellent process visibility and exceptional product quality.
In order to achieve faster measurement and tighter control response, a MiniTrak-O scanner is installed following the collapsing frame that measures the double layflat film thickness using an FG710S infrared sensor. This sensor provides co-extrusion thickness measurement for up to four components (such as costly Nylon and EVOH barrier layers) and provides the 8000 system with the needed information to perform multi-layer component control for product quality assurance and cost savings. This advanced blown film system incorporates two applications that provide significant performance benefits compared to conventional blown film configurations that simply measure the thickness of the film on the bubble. They are:
Double Layflat Separation Algorithm (DLSA): The system measures the double layflat film and then processes this data through a special algorithm that mathematically separates the top and bottom film layers to provide a continuous, full-circumference single-layflat thickness profile. The DLSA algorithm includes Accumulator Modeling and Die Rotation Modeling that accurately maps the film against die position.
The DLSA algorithm incorporates the collapsing tower and/or die input orientation and calculations for the following process elements:
Die or nip oscillation / rotation speed
Die or nip oscillation direction
Bubble twist and Melt Slip modeling
Die bolt / Air Ring mapping
The result of this sophisticated algorithm is a usable 360 degree thickness profile for both total thickness and barrier components within 3 to 4 scans.
Automatic Profile Control (APC): The APC control supervises the die bolt positions based on the DLSA profile measurement. The control also includes a ‘smart’ pulse alignment profile map. Profile control to less than +/- 2% has been achieved.
A significant number of systems have already been installed at major producers of meat and cheese barrier packaging films.