Static Eliminators

Chapter 1: What is a Static Eliminator?

A static eliminator is a device that emits a field of positive or negative ions to neutralize static electricity that is present in equipment, products, and devices to dissipate potential production and manufacturing problems. Materials that are positively and negatively charged reject materials that are also positively or negatively charged but will accept materials that are charged differently. In industrial operations, foreign substances, such as dust, dirt, debris, and contaminants, are attracted to charged materials and contaminate coated surfaces, products, and equipment.

There are several problems associated with static electricity, such as materials sticking together, sheets repelling each other, and a slowing of production due to an increase in rejected items. The presence of static electricity lowers the quality of products and inhibits efficiency and productivity.

The solution to the problem of static electricity is static eliminators, which can be passive or active. Active static eliminators are electrically powered by AC or DC current and emit positive or negative ions that neutralize static electricity. The devices come in a wide assortment of sizes, configurations, and power levels, which makes it possible to choose the most appropriate static eliminator for an application.

Passive anti-static devices operate without the presence of an outside power source and are energized by a static field on the surface of a material. They are low cost, easy to install, and effective for reducing static fields to 2000 V. The types of passive anti-static devices include brushes, tinsel, and cords.

Chapter 2: Types of Static Eliminators

Static electricity is a problem in all of its forms to production and manufacturing processes, especially in cold weather, low humidity, and dry air. In the printing industry and the application of coatings, it is important to eliminate static electricity for the quality of products and the safety of workers. In addition, the control of static is essential in applications and processes where isolated and non-conductive materials are present.

Unlike electric current, there has been very little study regarding static electricity due to the inability to complete any form of accurate analysis and the problems associated with measuring static electricity. The four major types of static electricity are static discharge in electronics, electrostatic attraction and repulsion, fire, and electric shock (ESD). The presence of static electricity requires the use of precautions, such as static eliminators that are designed to neutralize static electricity and prevent it from harming products and surfaces.

When static electricity has to be removed from production and manufacturing processes, active static eliminators are required that use high voltage ionization equipment that produce positive and negative ions. Passive anti-static brushes, pin arrays, tinsel, and ionizing cords have been used for many years as active static dissipaters and were the initial forms of static eliminators.

Bars

Anti-static bars produce an electrical field that causes air molecules to break down into positive and negative ions. Charged materials that pass by an anti-static bar will attract ions until the material is neutralized and no longer attracted to other materials. The structure of an anti-static bar includes a powered ionizing emitter of 20 cm (8 in) up to 5 m (16 ft) that points the ions at the targeted object. The use of compressed air in an anti-static bar extends the field that that bar can cover.

One of the purposes of bar ionizers is overcoming the problem of workstation ionizers that can be blocked from targeted items. They can be hung 43 cm up to 61 cm (17 in up to 24 in) above a workbench or mounted on a workbench directly over the target area. This removes the potentiality of anything blocking the flow of ions. Large bar anti-static eliminators can be used with automated assembly processes especially for the production of plastic film and laminations. The size of bar anti-static eliminators can be scaled up or down in order to cover the target area and be positioned such that they do not interfere with processes or operations.

Guns

An anti-static gun has a piezoelectric crystal that generates positive and negative streams of ions. When the trigger on the gun is squeezed, the gun releases positive ions while negative ions are emitted when the trigger is released. Anti-static guns are widely used on non-conductive surfaces, such as plastics, glass, ceramics, film, lenses, and microscope slides.

When the trigger of an anti-static gun is squeezed, pressure is applied to the piezoelectric crystal generating voltage and positive ions. A laser pointer on the gun marks the area where the static neutralization is being applied. Most anti-static guns are charged by AC or DC systems and are connected to the electrical system by a plug on the back of the gun.

Nozzles

Antic-static nozzles are small and are designed to eliminate electrical static in hard-to-reach places. They produce high velocity ionized air that cleans and removes static charges. Anti-static nozzles use compressed air for pinpoint removal of electrical static. They are ideal for cleaning parts and materials, while preventing the return of dirt, particles and contaminants. In large equipment, anti-static nozzles prevent double feed pickups and clean surfaces, tubes, and the inside of machines on conveyor lines.

The airflow of an anti-static nozzle can be changed by changing the nozzle tip. The flexibility of anti-static nozzles makes it possible to install nozzles with any configuration to meet the needs and requirements of an application. The shapes of nozzles can have a cross-sectional appearance of a square, rectangle, and the traditional round nozzle. Nozzles for anti-static nozzle static electricity neutralizers are easy to install, replace, and adjust.

Small anti-static nozzles are mountable and can be placed in narrow hard to reach areas with interchangeable tips. Flexible neck anti-static nozzles provide pinpoint accuracy with the easy positioning of the neck of the nozzle and are benchtop devices for use with sensitive equipment, such as electronics.

Blowers

Unlike the pinpoint static removal of anti-static guns and nozzles, anti-static blowers are designed to neutralize static over a large area. Since anti-static blowers produce high volumes of air, they can be placed a distance away from affected areas and can send wider ion patterns. Anti-static blowers produce large quantities of positive and negative ions that are sent into the air. The ions flowing through the air are attracted to charged particles. The high volume of ions neutralizes charged surfaces quickly and efficiently.

An anti-static blower’s effectiveness is tested using an electrostatic field meter that measures the electric charge that a blower generates. This has to be done regularly to ensure an electric blower is efficiently removing and neutralizing static electricity.

Fan

Anti-static fans are another version of anti-static blowers. As with blowers, anti-static fans produce positive and negative ions that are directed at objects with a static charge. They are portable, mobile, and easy to use. Much like a traditional fan, anti-static fans can be set to provide a wide range of airflow patterns. Like many forms of anti-static devices, anti-static fans have their high voltage monitored by an ionization indicator lamp.

Unlike blowers that are designed to neutralize large areas, anti-static fans are designed for work with sensitive electronics and help prevent the misalignment of small parts due to electrostatic jumping and the adhesion of plastic film. The use of anti-static fans in place of anti-static blowers is due to their lower cost, which is about one third the cost of an anti-static blower.

Air Knives

An air knife is combined with an anti-static bar for air amplification and to produce a high velocity sheet of ionized air as high as 25:1. The combined effect neutralizes static that sticks to or clings to a surface. The purpose is to neutralize the static charge for optimal dust removal in a single cycle. Air knives are very compact without any moving parts, which removes the need for maintenance. The created positive and negative ions are picked up by the high velocity airflow and propelled at great speed toward surfaces and products.

The popularity of air knives is due to their ability to deliver clean, dry, oil free air. They have a precision linear slot that drives ionized air at products and materials. The key to the process is the force and velocity of the air that neutralizes static electricity but is able to remove excess water droplets as well.

The rapid rate of the removal of dust, particles, and contaminants is easier with the combination of air knife and anti-static bar. The result is cleaner materials and objects, which removes any concerns regarding a product or part. Air knives are ideal for plastic web and sheet stock where tearing, jamming, and shocks can be a problem.

Inline

Inline static eliminators are used with air pressure tube conveying systems to eliminate material buildup due to clogs created by static electricity. They are a form of preventative measure for ensuring material flow, efficiency, and productivity. Inline static eliminators are designed with the same diameter tube as the pressure tube conveying system, which necessitates manufacturing each inline static eliminator to the specifications of a customer. They are designed with small anti-static bars that are positioned in a series along the length and sides of the tube. The number of anti-static bars varies in accordance with the diameter of the tube.

Micro Static Eliminators

A much needed and widely used form of static eliminator is a micro static eliminator that is ultra-small with a spot nozzle and wide area electrode probes, which can be adjusted to fit the requirements of an application. The size of micro static eliminators enables them to be built into the system of a machine.

Although micro static eliminators are very small, they have the same features as larger static eliminators, such as showing the level of electrostatic charge in an object, displays of ion levels, and alarms for when static elimination is not sufficient. They can be used for spot and wide area applications for removing static from part feeders, bonding machines, pharmaceutical pills and tablets, and metal molds.

Desktop Duster Box

A unique form of small static eliminator is desktop duster boxes that are used for cleaning dust and static removal for small to medium sized sensitive parts. Parts are placed in the box and detected by a photoelectric sensor, which begins the static removal and dust collection processes that are followed by an air blowing. The length of time in a desktop duster box is set by the controls on the box.

The combination of static neutralization, dust removal, and dust collection makes desktop duster boxes highly efficient and productive tools for the sensitive electronics and semiconductor industries. Although desktop duster boxes all perform the same processes, they come in a variety of sizes to match the requirements of the types of sensitive parts.

Ceiling Emitters

Work areas that require exceptional static electricity removal are cleanrooms where sensitive and fragile equipment perform critical experiments or involve the assembly of various types of electronics. Ceiling emitters, that consist of long rods and long bar, are hung in series from the ceilings of cleanrooms and use pulsed DC high voltage to generate air ion molecule clouds for maximum control of ESD in the work area of a clean room. They emit uniform ionization throughout the open area and have alarms and warning systems to inform of the necessity of corrective action.

In addition, ceiling emitters also eliminate particulate contamination, which is a constant concern for cleanrooms. Mounted on the surface of the ceiling or flush inside mounting channels, ceiling emitters eliminate static electricity and contaminates without damaging the aesthetic appearance of a clean room or interfering with the laminar air flow. Ceiling emitters are approved for use in Class 1 cleanrooms, which are cleanrooms with the highest standards and strictest requirements.

Alternating Current (AC) vs Direct Current (DC) Static Eliminators

AC and DC static eliminators function the same using high voltage to produce positive and negative ions to neutralize static charges. The difference between them is their range, where AC static eliminators work best at 20 mm up to 100 mm (0.79 in up to 3.9 in) while DC static eliminators are used for complex applications with a range of up to 1000 mm (3.28 ft).

The close range of AC static eliminators is due to the short life of their ionization, since the ions recombine quickly. DC ionization lasts longer but has peak performance when positioned closer to the target. As with all forms of static eliminators, their ability to eliminate static electricity is determined by their distance from the targeted object, with most static eliminators’ ranges being between 25 mm up to 400 mm (0.98 in up to 15.78 in).

Summary

The ten static eliminators described above are a small sampling of the many types of static eliminators available from manufacturers, who work closely with their clients to ensure that the right static eliminator is provided for the product a client wishes to protect. It is important to work with static eliminator manufacturers when making the decision to purchase a static eliminator system, since the size and type of product can determine which static eliminator to use. Manufacturers have the expertise, knowledge, and experience necessary to properly match the right static eliminator with an application.

Chapter 3: Passive Static Eliminators

Passive static eliminators are unlike active static eliminators that use electricity to produce positive and negative ions. They operate as self-energizing or on the induction principle, drawing energy from a static field that exists on the surface of materials. The various types of passive static eliminators are tinsel, string, brushes, and sprays. Passive static eliminators are low cost, easy to install, and can be replaced, switched, or removed with little effort.

Although the list of passive static eliminators can be divided into four categories, under each grouping is a wide range of types, sizes, shapes, designs, and configurations of passive static eliminators being manufactured for a specific anti-static function. There are limitations to the use of passive static eliminators, which have to be examined before using them. Under certain conditions, passive static eliminators are the perfect choice.

Passive static eliminators can prevent machines from jamming and assist with human static. When the static charge is very high, passive static eliminators can lower the charge to be neutralized by an active static eliminator.

Anti-Static Brushes

The key to static removal with anti-static brushes is their structure, which consists of low charge filaments that are neutral. The materials are chosen for their inability to give or receive electrons. Anti-static brushes with natural filaments are used for electrostatic discharge (ESD) in sensitive materials. Although natural filaments are commonly used for anti-static brushes, materials, such as brass, stainless steel, and anti-static, conductive, and high-density nylons, are also used.

Of the various forms of passive anti-static eliminators, anti-static brushes come in the widest array of shapes, sizes, and forms with variations in filament lengths, handles, widths of brushes, and the stiffness and texture of the filaments. There are standard anti-static brushes and custom ones designed for a specific application.

Anti-Static Tinsel

Anti-static tinsel is made from copper and consists of a multiple copper wire core for positive grounding and strength. They have a 32 mm (1.25 in) diameter and can be positioned slightly above the target material to be neutralized. The copper filaments concentrate the electric field and ground it. When in use, anti-static tinsel is connected to the earth for removal of static electricity.

Anti-Static String

Anti-static string is ionizing cord with conductive micro fibers that cause static charge to ionize and flow to earth. It is a durable alternative to anti-static copper tinsel and is sold like rope in reels of several feet. Anti-static string is suitable for use with high charges that move at high speeds and is commonly used on web and sheet applications for paper handling and packaging. As with anti-static tinsel, anti-static string has to be grounded during use by being attached to bare metal.

Like anti-static tinsel, anti-static string is positioned slightly above the target material and draped across it. It can be placed under or over the target material but never in contact. Anti-static string is an inexpensive and is a non-oxidation solution for neutralizing static electricity.

Anti-Static Spray

Anti-static spray is a combination of filtered water and alcohol that has molecules with positive and negative ions that neutralizes charged particles and prevents static build up. It assists in the handling of various materials and prevents paper, films, and laminates from sticking to each other. Anti-static spray is applied as a light mist and is effective in removing surface static electricity.

The popularity of anti-static spray is due to how convenient and easy it is to use. It counteracts static cling and the attraction of dust and is widely used by copier repair personnel to remove static from paper that jams copiers. Anti-static spray is ideal for removing static from folders, joggers, and fax machines and static build up on optics, disc drives, photographic materials, lenses, and metal rollers. The fast application of static spray to plastics, fibers, and cloth quickly eradicates static electricity. It is safe to use in sophisticated ESD environments where static control is a necessity. This is especially true in cleanrooms where moving or sitting in a chair can create static discharge.

Anti-static spray must be applied as a mist and not be sprayed such that it coats or soaks a surface. This is especially true with cloth, paper, and fabrics. Anti-static spray manufacturers offer a wide variety of sizes that can be purchased as part of a field service kit that includes static control products such as anti-static gloves, static bags, static brushes and ionizers.

Passive static eliminators do not use power and do not require any cost to operate. For the best results, they have to have contact with the conductive material, which may be inadvisable for certain materials, such as ones that are delicate that can be damaged by the contact. In addition, passive static eliminators can attract dust, dirt, and debris that may transfer to the targeted product. Passive static eliminators cannot be used with materials of different sizes, uneven surfaces, or complexity.

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Chapter 4: Uses for Static Eliminators

In the static elimination process, ionizers are used to neutralize static charge by generating positive and negative ions to offset the existing imbalance of ions. Static eliminators are a useful and affectual tool that manufacturers use to remove static charge and buildup for the protection of their customers and products. Since static eliminators are safe, efficient, and effective, compared to other static removal methods, they are the first choice of manufacturers when dealing with the problem of static electricity.

Cleanrooms

There is a long list of uses for static eliminators in cleanrooms, beginning with air showers where workers have contaminants removed using jets of air. The addition of static eliminators makes the cleaning preparation process more efficient. Static eliminators are added to air flow hoods and clean benches. Off and on winds generate static electricity during their operation, which attracts contaminants, dirt, and dust. Static eliminators neutralize the problem. Openings to a cleanroom can allow static electricity to enter the room and necessitate the placement of static eliminators.

Plastics

Plastics formed in a mold are electrostatically charged to force the plastic to adhere to the surface of the mold, which causes molded plastics to stick to the surface of a mold. As shapes become more complex and larger, the amount of static electricity increases, intensifying the problem. In addition, high speed molding creates a higher level of build up due to the rapid rate of the process. While other measures can be taken to improve efficiency, the installation of static eliminators, such as air knives, prevents particle adhesion and residual on molded products, which reduces waste and improves productivity.

Storage Facilities

Warehouses that store electronics have to be protected against static electricity that can damage shelved devices. AC and DC static eliminators are used under such conditions to provide positive and negative ions to neutralize any threats. Static eliminators are positioned in various parts of a facility, such as entrances, doorways, and other openings to prevent particles from entering a facility.

Electronics

Dust collectors that are used during the transfer of electronic parts can damage parts, while static eliminators, that don’t use force to remove dust, eliminate static charges and dust without need of forced air. They remove static charges from delicate electronics that are sensitive to dust and air pressure. Fine parts are easily neutralized with the efficient delivery of ions with bar and space saving static eliminators.

Personnel

During a regular day, people are constantly accumulating static charges, which necessitates the use of long-range static eliminators for use in large spaces where airborne particles are present and collect. In such cases, low frequency static eliminators are used that have a longer emission time of ions that repel each other and spread over wider distances. These types of static eliminators are ideal for work spaces where workers congregate.

Electromagnetic Noise

In areas where static electricity is released, electromagnetic noise is always present, which can cause electronics and other equipment to malfunction. Although static electricity is a problem in several other areas, in instances where electromagnetic noise is present, it is important to prevent ESD and stop the generation of electromagnetic noise. On production lines, the materials being manufactured can generate electromagnetic noise that can interfere with production. Static eliminators are used to correct the problem without coming in contact with products. In essence, it is a nonintrusive method for preventing assembly and production stoppage.

Chapter 5: Rules for Static Elimination

In order to get the best results from a static eliminator, it is essential that the rules for the process be followed such that the process and performance of a static eliminator is successful. The rules that apply to the use of static eliminators can provide a greater understanding of the necessity of the process and the reason for its use. In addition, such knowledge is helpful in the selection of the right static eliminator for an application.

Touching

If a material to be neutralized is touching a piece of equipment, roller, metal, or other material, the electric field couples with the touched body and prevents neutralization. It is important to wait for a material to separate before initiating the process. An exception to this rule is with DC static eliminators, which are able to neutralize charges between coupled bodies.

Timing

If a product is neutralized too early in a manufacturing process, it may pick up static electricity as it passes through other processes. A static eliminator should be positioned at the last possible moment of manufacturing.

Dust

It is essential that dust be removed as soon as possible to avoid molecular bonding that inhibits the ability of static eliminators to neutralize a product. For the process to work, dusty products or implements should be wiped down, dusted, and cleaned with a solvent. This is a reiteration of the touching rule, but in regard to dust.

Heat

Products that are hot after neutralization can still generate a static electrical charge. Materials to be neutralized should be cooled to around 40°C (104°F) before being neutralized in order for the neutralization to last. Static eliminator air nozzles and blowers are ideal for such applications, since they cool the item to be neutralized.

Speed

The faster products are processed and produced, the higher is their static electric charge. In some cases, it is recommended that two or more AC static eliminators be used for greater efficiency. Pulsed DC static eliminators are more powerful and are able to put up with higher speeds.

Surface Charge

The majority of static charges are generated on the surface of products, but in cases where a product is multi-layered, the neutralization of charges is more difficult. Under such conditions, the only way to neutralize the static charge is to wait until it moves to the surface.

Thickness

In most cases, the application of positive and negative ions removes static charge from both sides of materials. Although this is common, there are instances when a material is too thick and requires treatment on both sides to remove all static charge.

Chapter 6: The Dangers of Static Electricity

The power of static electricity is a form of electricity with which people are most familiar. It is for this reason that many people disregard the dangers of static electricity and view it as a nuisance rather than a danger. The hazards of static electricity require planning for protection against the threat of its presence. Areas where static build up occurs include gears, belts, powders, jet nozzles, metal tanks, piping, and rubber wheels, to name a few.

Electronics

The danger to electronics in regard to electronics comes from people touching the components of electronics, which generates heat that can burn connections, disrupt contacts, and break microchips. The created damage may not manifest itself immediately but can happen during the operation of a device. In such cases, measures should be taken prior to touching electronics such as anti-static gloves and static dischargers.

Electrostatic Attraction

Electrostatic attraction, and repulsion, is a force between particles due to their electric charges where there is an attraction between positively and negatively charged ions, which are oppositely charged. This particular problem is common with plastics, paper, and textile production and processing. Electrostatic attraction is visible in the materials during processing where materials will stick together, pull away, stick to equipment, attract dust, or wind incorrectly. The problem can be solved with the use of a static eliminator or static ionizer.

Fire

The risk of fire from static electricity is not common to most facilities, except in processes that involve the use of flammable solvents. The source of the static electricity can be underground equipment and moving conductors. The igniting charge can come from an individual wearing non-conductive clothing or the operation of underground devices. The proper type of footwear and clothing that allows electrostatic charges to dissipate and anti-static gloves can prevent electrostatic build up from people. To prevent underground machinery from producing electrostatic discharge, the equipment should be grounded.

Electrical Shock

Electrical shock from static electricity is something that everybody has experienced by shuffling their feet on carpeting. Although this is entertaining, the risk of shock in an industrial environment can be an issue that can cause accidents and harm people with heart conditions. This type of electrical shock is very common in plastics factories that have static electricity build up on the surface of products.

While the effects of static electricity are negligible, there are dangers connected with its presence and measures should be taken for the safety of workers and equipment. Many of the precautions, aside from the use of static eliminators, are simple and easy and require very little effort.

Chapter 7: Testing a Static Eliminator

There are several methods that are used to determine if a static eliminator is working properly. The easiest method is to measure the static level using a digital static meter, which is a hand-held, battery-operated instrument that displays the voltage and polarity on an object’s surface.

Another method is to see if there is the presence of ozone near the emission point of a static eliminator. When the compressed air of an eliminator is turned off, it is possible to smell the odor of ozone, which is pungent, sweet, and metallic.

When testing a static eliminator, anti-static measures should be taken, such as wearing anti-static clothing, caps, and shoes to make sure the person doing the testing is grounded. There are anti-static coveralls that are used by workers in cleanrooms that cover the body and prevent the emission of static electricity.

Compressed air source from a static eliminator should be clean, dry, free of particulate matter, and moisture. The parameters of the environment, such as the temperature, humidity, air flow, air pressure, and cleanliness should be observed and recorded as to how they will affect the readings.

Things that should not be present:

1. Metal conductors and groundings
2. Static removers, static generators, high voltage supplies, power sprays, and charged equipment
3. Charged insulation and sources of electrostatic energy
4. Any items that will block air flow

The static eliminator should be grounded and the testing instrument should be clean, properly adjusted, and in good condition. The temperature and humidity should be at an optimum level to ensure the proper performance of the electrostatic meter.

Conclusion

• Static eliminators emit a field of positive and negative ions that neutralize static electricity in targeted items, such as products, equipment, fabrics, and devices.
• Positively charged ions repel other positively charged ions but attract negatively charged ions. Negatively charged ions repel negatively charged ions while attracting positively charged ions. Like charges repel, and opposite charges attract.
• When static electricity is present, materials will cling and stick together, which makes it difficult to separate them. In addition to mutual attraction, static electricity attracts dust, grim, dirt, and contaminants to the surface of products that have to be removed.
• Static eliminators are divided into passive types and active types with passive types being simpler and self-energizing while active static eliminators are more complex and require some form of electrical power to operate.
• Active static eliminators are referred to as ionizers or neutralizers. They emit positive and negative ions at targeted devices to neutralize static electricity and eliminate potential production problems.

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