1. On-line ZD paper stiffness measurement
Aim: To implement a non-destructive, continuous measure of zd stiffness (single sided) for process use on paper machines compatible with current Aurelia on-line measurement platforms.
- Starch addition measurement (zd thickness profile efficiency)
- Recognise and control delamination issues
- Fast and real time paper machine forming setup
- Improved non-destructive prediction of paper SCT, ZD tensile and Scott Plybond, bending stiffness
- 3-D characterisation of manufactured paper.
- Determination of fibre quality
Traditionally, non-destructive zd measurement has been made using high frequency (1 MHz) ultrasonic pulses directed through the thickness of the paper sheet with a transmitter on one surface and a receiver on the other. The zd stiffness is calculated using the propagation time of the ultrasonic pulse through the paper.
The technique has a number of difficulties when considered for application to on-line, continuous measurement:
- The measurement is double sided (the paper is required to pass through a nip)
- Signal coupling into and out of the sheet is poor.
- Data rates (due to the pulse measurement) are low and signal noise is high
An alternative method that is compatible with Aurelia’s existing in-plane, on-line ultrasonic tester platform is suited to zd measurement on the paper machine.