The most common method of charge generation is triboelectric charging. Whenever materials are brought into close contact, a charge exchange may occur between the surfaces of the two materials. The magnitude of this charge exchange will depend on a number of factors, but the result is two oppositely charged objects when the materials are separated. The second common method of creating static charge is known as inductive charging. This occurs when a charge is “induced” on an isolated conductive object that is brought into the field created by the charge on another object.
Air ions are molecules of one or more of the gases that make up air (nitrogen, oxygen, carbon dioxide, etc.) that have gained or lost electrons. If they lose electrons the molecules have a net positive charge, and are “positive ions”. If they gain electrons, the molecules have a net negative charge, and are negative ions. Air ions are a normal constituent of outdoor air, but natural ion levels are too low to be used to neutralize static charge in indoor environments.
The moisture content in the air affects the conductivity of certain insulating materials and their ability to hold static charge. The higher the relative humidity (>50%), the higher the conductivity of these materials. Conversely, the lower the humidity (<30%), the more insulative these materials become and the more charge they hold. Logically, it would follow that high humidity would be an effective means of controlling static. However, even under high relative humidity, unacceptable levels of static charge can be generated and remain for long periods of time. Additionally, high humidity can contribute to other problems including oxidation and soldering difficulties. Using high humidity as a means to control static charge is slow, uncomfortable, expensive, and often ineffective.
No single method exists for controlling all static problems. The proper use of equipment and remedial procedures help cure most static problems. Grounding:
Static on a conductor can be easily controlled if the object is grounded. Grounding provides a path so that charge can migrate to ground, effectively neutralising the charge. However, grounding an insulator does not work, because charges do not migrate on insulators. Antistatic or static dissipative materials:
Insulative materials, usually plastics, that are made conductive with the addition of carbon or metal fillings. The conductive dispersion can be adjusted depending on the amount of fillings added to provide resistivity ranging from fully conductive to dissipative. Ionisation:
Air ionisers work by flooding the atmosphere with positive and negative ions. These ions are attracted to ions of the opposite polarity on a charged surface. As a result, the static electricity that has built up on products, equipment and surfaces is neutralised. Education:
Training personnel and making them aware of electrostatic issues and the need for antistatic gloves, suits, smocks, and wrist/heel straps can make a large difference in the amount of problems that occur in a production facility.
There is no “best ioniser technology” for all applications. The application will determine the appropriate type to use.
This depends on the following factors:
position it too far “upstream” the charge could be regenerated by rollers or other static generative processes.
How far from the material? This depends on the type of static eliminator – there are short range, and long range static eliminators. Whichever type you use, the life of the ionised air produced is limited and generally good guidance says “the closer the better” subject to the minimum distance specified by the manufacturer.
The material should be in free air! This is a very important rule which is often ignored. When a material touches another object, such as a roller, the static charge couples with that object and is not available to be measured or neutralised. If you put an anti-static bar to neutralise film when it is travelling over a roller it will not be effective. This is probably the most common mistake in the installation of static control equipment.
You can use 2 (old) Analogue devices on port 5 and 6 of the Manager IQ Easy. This can be the ThunderION or Performax IQ Easy.
These devices will get the 24V from the manager and will indicate the HV OK signal from the bar to indicator if the bar is functioning OK. (Not OK means red Warning)
The bars can be set to run or standby or switched with remote on/off via the Manager IQ Easy.