User's Manual for the Wound Roll Sizer


To calculate wound roll dimensions, such as diameter or length, and other properties, such as weight or inertia.

In commerce, rolls might be wound to diameter, sold by length with thickness being reported/specified even though other combinations are also common enough. In any case, wound roll geometry is a vital part of doing business. In an ideal world, roll geometries would be easily measured by sensors on the winder itself and the information desirably printed on the label or otherwise passed along with each individual wound roll. However, there are cases where this information is not readily available. This includes winders that are not equipped with those sensors, wound rolls where the data had been lost, partial wound rolls and new product design. Thus, the need to be able to estimate roll dimensions when sufficient other information is available.

How To

Choose the units of measure of either Metric or US. Enter everything you know in the units specified and everything you don't know will be automatically calculated.

While you can choose either Metric or US units, you cannot specify which type of units within those systems are used. The most common usage is fixed. For example, thickness will given in µm (0.000,001 meters) and mils (0.001 inches). Pay special attention to make sure that your input/output values are in the units specified or convert to/from as needed.

The wound roll has three important properties: web thickness, web length and wound roll outside diameter. If you know two of these, the third can be calculated. With other information, such as web width, many other parameters such as weight and inertia can be calculated. What makes this calculator useful and also possibly a bit confusing is that you could change roll weight, for example, and note that many other fields are recalculated. The reason is that changing the roll weight assumes that the length is what was changed rather than the basis weight, width or other factor. Many other similar relationships are also employed in the calculator. Another point of confusion might be when you enter only some parameters such as length and thickness and note that the predicted roll weight is not what yours is simply because you did not enter your particular width and the default value remained. The simple way to avoid confusion is to simply enter what you know field by field until all fields that you (easily) know are entered. Then re-check your inputs to see that they have not been overwritten by an automatic recalculation.

Thickness Compressibility Factor

A final small complication awaits the sophisticated user. That is the predicted roll dimensions will be different than the real world by a few percent. The reason is that rolls of film, for example, will also include some air so that the effective or average or in-roll thickness is slightly greater than the test lab measured thickness. Its thickness compressibility factor is greater than one in this situation and essentially is a measure of both how tight the roll is wound as well as how much (percent) air that is inside the wound roll.

In contrast, compressible or spongy materials such as foam, nonwovens, tissue and textiles may have in-roll thickness less than test lab measured thickness. This is because the pressure in which the test lab measures thickness is different than the average pressure between the layers in the wound roll. Again, the difference between calculated and real dimensions is sensitive to how tightly the roll is wound as well as other factors.

In order to improve the performance of the calculator, you need to have a wound roll of known dimensions already. Simply adjust, trial-and-error if need be, the compressibility factor until the calculations match the known roll. Then use the same compressibility factor for subsequent calculations. Caution, the factor will change if you change roll size a lot, but especially if you change 'grades' or winding tightness.

Because an accidental setting of this factor might mislead you, if the value is <0.9 or >1.1 then it is highlighted in pink as a reminder.

© Copyright 2013 Steven Abbott TCNF