Pulp Paper & Logistics


HEIMBACH 19


Figure 3: The first ODIN measurement is always taken directly before the reel


where customer satisfaction is paramount, access to measuring tools with this degree of precision is crucial.


Suitable for every paper grade ODIN equipment can be used on any paper grade, whether graphic, tissue or packaging. There are, however, a few prerequisites that have to be met to make measuring possible at all. First, machine speed has to remain constant throughout the entire measuring process. Furthermore, the sheet must not be too opaque. ODIN performs by transmitting a light beam through the web to record its data, and in some cases this might mean that filler material or the density of a particular paper grade may preclude the use of


this equipment. Fortunately this is only rarely


the case, and normally it is possible to scan all webs up to a basis weight of 140gsm. Below this threshold most sheets are sufficiently translucent to allow measurements to be carried out successfully.


Process logic decides At this point it is worth taking a look at the process. In this respect ODIN is rather unusual. Instead of following the standard rule: ‘start at the front and finish at the end’ when determining periodic MD mass variations, the opposite is the case. The first measurement must invariably be carried out just prior to the reel – at the end of the process (see Figure 3). There is a simple explanation


Figure 4: Clear peak – clear fault, at 133.33 Hz


in this case for ‘beginning at the end’, as it is only at this point that it can be certain that the faults exist and detected by measurement. Here, several barring frequencies (or of course just one) can be recorded to start searching for the precise location of the origin of the problem. This is done by going in the reverse direction to the travel of the machine. Simply put, each barring occurrence has one – or several – source which must be spatially located. It is exactly this determination of locality that is an important element of the ODIN measuring process.


Precise and reliable Once the source of the barring is known the cause can be identified. This is done either by measuring vibration or


by recording the speed of a rotating element (such as roll, pump, separator). In our case study Figure 4 shows the result. At exactly 150mm, the mass densification is present. This value corresponds to a barring frequency of 133.33 Hz (see above). It should be noted, that the diagram could potentially show two, three or more variations. This would mean having to find several sources of faults, about which we cannot detail here. The key here is finding the one original factor that is responsible for the disturbance that has been identified at 133.33 Hz.


Measurement point by point Figure 5 shows the full paper machine, limited for the purposes


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Figure 5: The six ‘classic’ measuring positions on a paper machine May/June 2018


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