Automatic Layflat Calibration

Reduce scrap or out of spec. rolls with new accuracy automation system.

Improve long term accuracy: Automation that accounts for film shrinkage / stretch


Final film width after the primary nip of a blown film line is dynamic; as the film makes its way down the line, various factors effect the actual film width as it is wound on the core. Film shrinkage and stretch occur at changing rates due to the following factors:

  • Web Tension
  • Polymer Properties
  • Film Gauge
  • Fim Temperature
  • Ambient Temperature
  • Factory Pressure Change

For precision width control, the layflat system must be calibrated to account for shrink / stretch. The Automatic Layflat Calibration (ALC) feature acts as a final QC checkpoint to correct the layflat system, compensating for previously uncontrolled variables.

For production where job orders change often, ALC speeds up job changes, saving time, saving scrap and keeping the roll precisely on the customers specification.

 

Smart Calibration
ALC is configurable to calibrate film width in
the following key scenarios:

  • Line Start-up
  • Size Changes
  • Hole Recovery
  • Layflat Drift

ALC is only armed when a stable bubble is
present so as to avoid false calibrations and
the software can detect film curl or wrinkles as
they pass over the flat width bar to avoid false
calibration events.

How it Works

Utilizing layflat information from an integrated flat width measurement bar, final layflat width at
the winder is automatically calibrated to the layflat control system, accounting for film shrinkage /
stretch as it makes it way down the tower to the winder.

Infrared sensors on the measurement bar ensure an accurate layflat reading near the winder. This eliminates inaccurate tape measurement readings, accidents due to a tape measure getting caught in the web, and also frees up operator time and attention.

Mechanics of Automatic Layflat Calibration

Flat Width Measurement Bar: Kundig FE-8

The FE-8 is a non-contact measurement bar which uses two travelling infrared sensors to detect the flat film edges (shown at right), thus calculating the actual film layflat.

The unit is ideally placed near the finished roll, in order to measure actual width after the film has undergone stretch and shrink.

Especially for large webs, this measurement method leads to much more precise readings than a manual tape measure can provide.*

*Not compatible with inline gusseting production

Click on image to zoom

Two Points of Measurement

Layflat control is carried out by ultrasonic
sensors as shown on point (A), (shown at right). They are strategically placed to make timely adjustments to layflat variances thereby avoiding control lag. Here, the system adjusts for air loss in nip leaks and pin holes, or layflat gain due to internal thermal expansion or ambient temperature changes.

Point (B) shows the second measurement point via the FE-8 width bar. It is strategically placed to account for stretch / shrink of the web as it comes down the tower. It adjusts for shrink variance due to material, gauge, job size (width) and temperature changes.

Final width as measured by the FE-8 is
automatically calibrated to the width control
system.

 

Click on image to zoom





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