On-line, Continuous, ZD Non-Destructive Stiffness Measurement

Aurelia is developing an on-line, continuous, single-point zd stiffness measurement suited to the technology platform already developed. This development will give a continuous measurement of zd TSI as the paper is being made, reporting zd tsi values within the reel a few times a second.

This measurement will indicate fluctuations in former operation; the efficiency of starch addition either in the approach, wet-end or size-press; refining and press issues; as well as changes in product performance – all in real time.

ZD TSI coupled with existing in-plane (MD and CD TSI) measurements made continuously on the paper machine mean that product performance can be known in real time.

51b30f_bd2955485db545449a62c1b15281a6bc1. Paper characterisation Ultrasonic tester

Aim: To implement a non-destructive, continuous measure of zd stiffness (single sided) for process use on paper machines.


  • Optimising starch addition measurement (zd thickness profiles)
  • Control liner and medium delamination issues
  • Fast and real-time paper machine forming setup
  • Fast prediction of paper properties
  • 3-D characterisation of manufactured paper.
  • Bench reference for on-line stiffness measurement


Paper requires nine individual engineering parameters to fully describe its engineering performance. This project seeks to design and build a test unit that determines more than the usual in-plane parameters routinely obtained from bench ultrasonic testers that deliver in-plane Tensile Stiffness Index (TSI). The additional engineering parameters provide more insight into paper sheet structure and hence forming process than traditional measurements. It is expected that additional correlations with new quality and process measurements would be developed once the measurements can be made available quickly and reliably.


What would it do?

In a nut shell, it would completely characterise the measured paper sheet (in terms of its elastic properties and engineering parameters) in a few seconds. In the same time it would estimate important strength properties like bending stiffness, ring crush, SCT, tensile strength, orientation angle and effective (structural) thickness and report them.

What would it be used for?

In its simplest form it would replace a number of physical test room tests like ring crush. Imagine obtaining md and cd ring crush tests in a few seconds (also many other tests, without cutting the paper and all on the same piece of paper) [Fig 14]. For a given furnish recipe (the furnish type could be entered) the test is as good as the test room.

More interestingly, the fundamental engineering stiffness or compliance will give insight into the operating state of the paper machine – showing how are the fibres aligned, into or out of the paper, levels of bonding in different directions, shear stiffness believed to be highly related to delamination and out-of-plane stiffness that relate to zd tensile and scott plybond tests. The overall “goodness” of the fibre furnish being used. Shrinkage and strain of the sheet during manufacture – with the Poisson ratios of the sheet. Fast cross machine performance profiling and setup.

ZD cont