12 HEIMBACH


Pulp Paper & Logistics


Trust is good, but control is better


Serious problems in a paper machine were solved by the Heimbach-TASK team after it used a combination of proven measuring methods – in particular, ODIN, vibration measurement and hood balance. PPL reports


throughout the machine and also complained of barring in the paper. Furthermore, the customer was also finding it very difficult to meet planned production volume targets, a result of being forced to run the machine at significantly lower speeds than normal. It had not been possible to detect any causes for the reduced production speed and barring using on-machine measuring and control technology. Right from the start, it was


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clear that not only was the job in hand particularly tricky, but that swift action was essential. The customer was not only dealing with quality problems, his production capacity was also limited. There was no time to waste and therefore TASK immediately implemented several measurements simultaneously to kick off what was a comprehensive investigation. Using their ODIN equipment, the paper web was considered step by step against the machine direction (starting at the reel) to identify the source of the barring through an exclusion process, of which more will be explained later.


First irregularities During the first measurements in the forming and press section, everything appeared to be in perfect order. The drainage


May/June 2019


mill producing fluting and linerboard had reported significant vibrations


Figure 1: The FFT analysis of the second press top felt shows an irregularity at 12.56Hz


analysis in the forming section showed no abnormalities and the jet speed (jet-wire-ratio) was also satisfactory. Routine felt measurements with Presstuner and Feltperm determined the water content and permeability of the press felts. It was here that the first clue was identified: In the second press top felt, the FFT analysis of


the water content showed an MD irregularity at 12,5Hz (as shown in Figure 1). The TASK team then placed their ODIN measuring fork directly in front of the reel. A barring was immediately recognisable, and the deviation was also at the same measurement, 12.56Hz. To identify the origin of the mass


variation, TASK chose some upstream measuring points. Both before the suction couch roll and immediately after the headbox (as shown in Photo 1) the same disturbance frequency at 12.56Hz was found. The fault must, therefore,


have originated earlier in the production process, either in machine components or within


Photo 1: The ODIN fork in use – directly behind the head box


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