Tension Loop Control for Clear Plastic
In this application, monitoring of the tension loop control is done by an ultrasonic sensor, the Banner S18U. The S18U bounces sound waves off of the clear plastic for a reliable and consistent sensing application. Standard photoelectric sensors have difficultly detecting clear material, particularly if its condition changes – in this application, the loop will fluctuate.
As the loop fluctuates, its distance from the S18U also changes. The sensor continuously reports the measurement of the loop changes back to the system controller via an analog output, either 0 to 10V dc or 4 to 20 MA, depending on the model. The controller then uses the analog output information from the S18U to adjust the speed of the film and maintain a consistent loop and proper film tension.
The S18U is also equipped with temperature compensation for consistent sensing performance, eliminating additional setup and configuration if the ambient temperature varies widely or changes.