The word “static” means “stationary”. Static electricity is a stationary electrical charge. In an atom, positively charged protons are balanced by negatively charged electrons. Losing or gaining electrons affects the charge. When large numbers of atoms lose or gain electrons, a noticeable electrostatic charge is created. The surfaces of non-conductors and isolated conductors are susceptible to the creation of static charges. Conductors differ from insulators in how easily a static charge moves or is “conducted”. When an electrically isolated conductor becomes charged, grounding the conductor can neutralize it by allowing the charge to flow to ground. Insulators do not allow charges to move freely, so grounding is not sufficient to eliminate static. Use of an active ionizer is the only way to reliably eliminate static on insulators. Many industrial materials are insulators, such as rubber, glass and plastics. Their desirable qualities make them essential to use, however, they are likely to become electrostatically charged during processing.
These processes include:- Peeling laminate
- Unwinding a roll
- Separating surfaces
- Wind-up operations
- Collecting products in bins.
Production jams, quality problems, dirt attraction and rejects are all consequences of uncontrolled static.
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Only an ionizing static eliminator can neutralize a non-conductive material. If an ungrounded conductor becomes charged, it can be neutralized by simply connecting it to an earth ground. Electrons do not move freely on insulators, even if they are grounded. Because of this, the only reliable way to neutralize an insulator that has become charged is to use an active static eliminator.
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How is Static Generated?
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Static electricity is a surface phenomenon and results when two or more surfaces are in intimate contact with each other and then are separated. During contact, surface electrons, which are negative, migrate from one surface to the adjacent surface. When the surfaces separate, the surface that gains the electrons becomes negatively charged, the surface giving them up becomes positively charged. The magnitude (field intensity) of the charge is dependent on many factors such as type of material and their physical and electrical characteristics, temperature and humidity, contact pressure and speed of separation. Typically, the greater the pressure and speed of separation, the higher the charge. Static charges tend to be higher during winter months due to lower ambient humidity. When humidity is high, materials such as uncoated paper tend to absorb moisture, making the surface semiconductive, allowing some of the charges to flow to ground. .
This friction, contact and separation, is called Triboelectrification. The polarity of the resulting electrostatic charge is dependent on the materials involved and their position on the Triboelectric series chart (available upon request from SIMCO). The higher a material is rated on the chart, the greater the propensity to become positively charged when frictioned with materials rated lower on the chart. An example of this is, if wool were frictioned with steel, the wool would be left positively charged and the steel negative. If you then frictioned the steel with Teflon, the steel would be left positively charged while the Teflon would be negative.
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