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Insulating Yourself from the Effects of Static Electricity

(September 2008) posted on Tue Sep 16, 2008

Is static standing in the way of quality and productivity in your shop? This discussion will help you identify sources of static electricity as well as the types of systems available to eliminate it from your production process.


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By David Rogers

Do your prints suffer from ink-adhesion problems or surface contamination from dust and particulates? Having issues with media sticking, binding, or misrouting? If so, you may be shocked to learn that your issues are likely rooted in static electricity. Here you’ll learn what static electricity is, how it occurs, and the methods available to counteract it.

 

What is static electricity?

When a material or object holds a net electrical charge, either positive or negative, it is said to have a static charge. The term static is a relative one, as in many cases static charges will slowly decrease over a period of time. The length of time is dependent on the resistance of the material. For practical purposes the two extremes can be taken as plastics and metal. Plastics generally have very high resistivity. This allows them to maintain static charges for long periods of time; on the other hand, metals have very low resistances and an earthed (grounded) metal object will hold its charge for an imperceptibly short period of time.



Static electricity is usually measured in volts. The voltage present on a material depends on two factors: the amount of charge on the material and the capacitance of the material. The simple relationship is Q = CV, where Q is the charge, V the voltage, and C the capacitance of the material. For a given charge on a material, the lower the capacitance the higher the voltage, and vice versa.

Plastics generally have very low capacitive values and hence a small charge can produce very high voltages. Conversely, metals tend to have high capacitive values and therefore a relatively high charge will produce low voltages. This is why, in practice, problems with static electricity are most noticeable when working with plastic, as it is the voltage level that causes the attraction of dust, operator shock, and misbehavior of materials.

 

How is static created ?


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