We are getting higher Static Charge development in the slit reels, more in lower thickness and smaller widths. Please advice, How to get it reduced. Our slitting machines are equipped with mechanism of discharging. Yet it is not working properly in thinner films and lower widths.
Answer
Do you measure the static charge on the web?
When you mention a static neutralizer is this a simple carbon brush, tinsel wire, or an electrostatic discharge bar. If it is the latter is this a fixed voltage system or is there some kind of feedback or tuning?
The reason I ask these questions is that there are a variety of possibilities. If the web material is the same for the thicker and thinner films it may be that all you are seeing is that the static charge is the same on both the films but the lower stiffness of the thinner film is showing the effects more visibly than the thicker film. Typically if the webs are the same material then over the same rollers you would expect the triboelectric charge that is generated will be of the same magnitude.
The charge generated can vary also with winding tension and well as humidity. Humidity is a mechanism to dissipate charge and so on days of high humidity the charge generated will be lower than on days of low humidity.
Static will be generated at every roller in the winding system. The static charge is cumulative and so it is important to have a measure of the charge on the web so that the positioning of the neutralization system can be optimized. It may even be that more than one neutralization system is needed. The static charge will be generated on both sides of the web and so it is also important that the neutralization is done on both sides of the web.
So I would suggest that you measure the static charge during winding at different positions along the web and look at how effective the neutralization is. This will also tell you if the position of the neutralization is in the correct position. In some cases it may be necessary to add a second neutralization station just before the rewind.
If the neutralization is an active one then it is also possible that it is set too high and instead of just neutralizing the surface it is in fact charging the surface but with the opposite polarity.


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