Perfectly calibrated and correctly displayed jet speeds – or ‘jet-wire ratio’ - are the basis for being able to manipulate the formation and some of the stability characteristics of the end product. FIRST RESULTS The measurements began and the jet speeds as well as those of the forming fabrics of the filler, back, and surface layers were identified. The first significant result was that all three fabrics were running at exactly the same speed (see Fig.1), so that TASK was able to quickly reassure the production manager with regard to his first concern. The speed displayed in the control room also corresponded to the result of the measurements. However, in the back layer a major difference of jet speed was discovered: The measured speed was around 35m/min below the value that was shown in the control room. It was suspected that the problem might be down to a calculation error and/or incorrect programming of the speed indicator. RATIO - THE DECISIVE FACTOR Next, together with the paper makers on site, Heimbach dealt with the speed differentials between jet and fabric, i.e. the ‘ratio’. You can appreciate how fundamentally important the provision of the correct value is in this context as fibre orientation and formation are set to these values. Even though the back layer appeared to have a ratio of 10m/min, the measurements that were taken showed -25m/min (Fig. 2). In this circumstance, the paper makers quite Perfectly calibrated and correctly displayed jet speeds… are the basis for being able to manipulate the formation Jet speed (back layer) Fabric speed (back layer) Figure 2. Both fixed measuring points in the back layer. WORLD PULP&PAPER 15