Reason for static Control static can cause several problems in a production facility.
In the film, extrusion for static can cause edges to curl and jam machinery.
In injection molding, the problem tends to be the attraction of dirt caused by static charge onto the part. Thus, creating painting and packaging issues.
Today there are many ways to eliminate the static buildup on parts. More powerful AC static bars and DC systems that can work farther away from the target product eliminating static charge. Neither requires any air.
Small packaged blower systems with air can assist in static control for very slow-moving production. Because introducing blower air, tends to be turbulent. The “ions,” pushing further, also re-combine. Especially as the distance grows if the target moves too fast,. There is insufficient time to eliminate the static simply because the ion concentration weakens.
Using the laminar flow of a compressed air-operated air knife or an annular air amplifier will push the “ions,.” Their re-combination will slow, but it still will weaken over distance.
So it should be with great caution when you come across claims of removing static from a target many feet away. Specifically when no time frame is specified, as the time needed can be quite long.
Even a static bar with no air behind it, several feet from a highly charged target, will still remove the static “given enough time” – again, a long time.
And in any production line, that exposure time is severely limited for obvious reasons.
Reason for Static Control With Air Suggested Products
If the distance is significantly considerable from the target or the static charge is exceptionally high on the target, the only way to remove the static and clean the part of dust and debris in a production line is to use a fixed bar or pin ionizer strong enough.
Providing a firm Ion Pin with their Ion Blaster Beam being mounted to a plastic attachment. By avoiding grounding, which can weaken the static elimination pin.
They have a standard and an extra strong static bar (which produces more ions for static elimination when dealing with a fast-moving and highly charged target) with their Ion Air Blade Ionizers.
When considering static elimination, try to avoid using air, especially if the purpose is solely for removing static charge, even if you cannot get close to the target.
But if cleaning is necessary, then an air source,, will be required with the static-eliminating device.
But do not get fooled that air alone, no matter what the source, will extend the range of the static eliminating “ions” without weakening the effect, thereby extending the time necessary for exposure to remove the static charge.
The only effective way to ensure static removal is cleaning from a distance. With a stronger concentration of static elimination ions.
Nex Flow offers additional consultationin using air with static and can advise on the optimal solution for your facility.
As mentioned in other blogs and articles, one of the key indicators of a well-made and properly designed compressed air operated air knife is relatively even flow across its length.
When you realize that you are dealing with very small air gaps over a long length, the tolerance and care required to manufacturer and assemble such products can be challenging.
One testament to the quality of Nex Flow® air knives, in particular the X-stream® Air Blade® air knives is that they are fully anodized. That process alone, if not done properly can impact the gap tolerance over even short lengths.
Nex Flow® air knives, (and in fact all aluminum material products) are anodized so there is proper protection for the product in an industrial environment. Most other air knife produces simply are incapable of doing this well, and most do not. If not done properly it can effect even flow and even proper flow from the small gaps existing the air knife (and other air amplification products).
In an article “Multilayer Blade-Coating Fabrication of Methylammonium-Free Perovskite Photovoltaic Modules with 66 cm2 Active Area” by Maximilian Ernst, Jan-Philipp Herterich, Christoph Margenfeld, Markus Kohlstädt, and Uli Würfel”, Nex Flow® is referenced in the experimental section where the 6” Model 10006X X-Stream® Air Blade® air knife was used with nitrogen.
Nex Flow® quality and producing even flow is very important. In fact subsequent to the article when another supplier was used by mistake, they returned hose units to correct the error when they could not get the same, necessary even flow from the poor copy.
We are privileged to be part of these and other research projects that help to confirm the value of Nex Flow® and welcome the opportunity to be part of many more.
Static electricity is an imbalance between positive and negative charges in materials. Most people have experienced it in everyday life whether it be with their laundry being “clingy,” making a balloon stick to a wall after rubbing it on your clothes, or when walking with socks on the carpet and getting a small shock from the doorknob. All objects are made up of atoms which have positive and negative charges, like charges repel each other (positive-positive, or negative-negative), while opposite attract each other (positive-negative).
Static attraction and Repulsion
Static electricity is a result of an imbalance between positive and negative charges when two objects or materials come into contact. The surface electrons (charges near the surface of the object) try to balance each other while the two surfaces are together. Let’s say there’s object A and object B. When object A and object B are touching, “A” gives up electrons and becomes more positively charged while “B” collects the extra electrons and becomes more negatively charged. When the two materials are separated, an imbalance occurs with the surface of “B” having a surplus of electrons and the surface of “A” having a shortage of electrons. These charges build up when they don’t have a direct path to the ground, and can eventually build up enough to cause a spark to a nearby grounded or less charged object in an attempt to balance the charge.
In various industries – this can cause issues with static charge knocking out sensitive electronics near the statically charged area, cause curling in plastic web processes that can cause jamming of machinery, or charged materials attracting dirt causing cleanliness issues in packaging, coating and painting operations. It can also be a nuisance and even a danger to personnel if being subjected constantly to static charges, especially if the charges are high.
Static charge is best eliminated just before the problem created by the plastic occurs. For example, if the problem is dirt on a part, it is best to eliminate the static “before” the dirt is attracted to the part. Sometimes it is not always possible to do that in which case the dust must then be removed. In such cases you can use an anti-static devices coupled with a compressed air operated air knife or air amplifier (ionizer bar in the case of an air knife and spot ionizer in the case of on amplifier). These products “ionizes” the air from the blow off units that bombard the statically charged surface with alternating positive and negative ions, which combines with the opposite charge on the surface of the part thereby eliminating the static charge. This makes it easier to blow off the dust. Nex Flow examples would be the Air Blade Ionizer and the Ion Blaster Beam. Normally dust can be blown off but if sticky, the force may not be enough and wiping may be necessary. Blower systems can also blow off dust but they need much higher volume and stronger ionizing systems due to turbulence. (Compressed air systems provides laminar flow and work better with ionizers).
When the problem is not dirt, and the anti-static device can be close to the problem area, no blow off or air is needed, only the anti-static device itself. Today the most common static removal technology is still AC technology. Normally, these static removing devices need to be very close to the part unless air is supplied which allows it to be a bit further away (and of course can also clean). Nex Flow also has an extra powerful AC ionizer for longer distance mounting and also if the static charge is extremely high for better static elimination. There are also now DC systems which operate farther away than AC systems from the target. They are also effective in blow off and cleaning of statically charged parts.
Two measurement devices are important when trying to control static electricity. One is a voltage measuring device such as the Multicheck which indicates if there is adequate voltage at the “pins” on the ionizer which generate the static removing ions. This will confirm if the static removal system is working. If the voltage is below the normal level it could be from either dirt buildup on the device and cleaning is necessary or there is damage somewhere in the system. The other is a static meter. Nex Flow has a lower cost and a more accurate higher cost version depending on the needs of the particular application. The static meters measure the static charge on the part before and after application of the static removal action. This will indicate if the system works as required.
Nex Flow has many years of experience in static control and can address any application where static may be causing issues in production, safety and/or cleanliness.
Air knives can be compressed air operated or blower operated and different factors determine which is optimal to use. This article will be focused on the different ways you can set up a compressed air operated air knife. Compressed air operated air knives are used primarily for drying, cleaning, and cooling and also for coating control and drying. There are multiple ways to set-up an air knife system depending on the application.
Below is a list of five common application and the basic suitable set-up
Drying or removing liquids from the surface of parts
Debris blow off from parts with special focus on how to remove static electricity from plastic parts that need to be cleaned
Coating control on parts when a coating is applied and needs to be spread evenly over the part
Drying or setting of a coating once applied to the part
Cooling of materials
Drying or Removing Liquids
Compressed air operated air knives are excellent for drying applications especially when drying relatively smooth and flat surfaces because of the high shear force. Blower operated systems often rely on heat as well as large blower mass flow to remove liquid but this can often leave stains on the surfaces left over from chemical residue. Compressed air operated units will have the added energy to remove all the liquid minimizing any possibility of stains. In addition, you need much less of a footprint to dry in any conveyed system as any liquid droplets left after drying are so small they evaporate very quickly. In these applications the air knife flow is directed against the direction of the moving product about 3 degrees in slow moving situations and incrementally increased to as much as 30 degrees for fast moving applications. The actual pressure used depends on speed and viscosity of the fluid removed and the roughness of the surface where the liquid is deposited. The greater the speed, viscosity and roughness, the more pressure is needed. Input air pressure can range anywhere from 60 to 80 PSIG.
Debris Blow Off
Compressed air operated air knives are also ideal in blowing off relatively light debris as compared to blower systems for the same reason as when dying, ie: light scrap off conveyors, dust and debris. The same rules apply regarding the angle of the air knife as with drying and is again directed against the direction of the moving target. It can be 3 to 30 degrees depending on speed but also depending on the nature of the material being blown off. For dust blow-off – it can be treated like liquid. For larger material or clumps of product, the angle can vary widely and needs to be tested for best effect in cleaning. Pressure however can often be very low (as low as 30 PSIG for light dust and debris) but of course can ramp up to 80 PSIG for heavier material. For very heavy material, the air gap of the air knife can be opened up for more force and power but that will also increase the amount of compressed air needed. For particulate or objects that need to be removed but only show up intermittently, a sensor system can be set up to detect the material and turn on the air supply only when needed to conserve energy as compressed air operated air knives can be instant on and off in operation. When having to clean particulate for statically charged surfaces such as plastics or film, an ionizing bar (static eliminator) can be attached to the air knife. When used in conjunction – unless the particulate is also very sticky – pressure as low as 30 PSIG and even less is capable of de-dusting a statically charged surface. Learn more about how a static eliminator works. An example of such an air knife with a static bar is the Air Blade Ionizer. If noise is a concern a Silent X-stream® model is also available. For very high charges or fast moving target, a stronger static bar may be used as with the our Triple X Air Blade Ionizer.
Coating Control
A compressed air knife with a very sharp edge air flow such as the X-Stream Air Blade® are ideal for use in controlling the level of coating applied to a product. The sharp, even and targeted flow from this unit can control the amount of coating on a product as the coating is first applied, then spread with the help of the air knife. The required pressure depends on speed and the depth required for the coating but easily controlled with a regulator and can vary widely depending on the viscosity of the costing as well. In coating control the laminar flow produced is important and gives much better control than the more turbulent flows produced by blower operated systems. In coating control the angle of the air knife is usually around 3 to 5 degrees due to the slower speeds involved.
Drying or setting of a Coating
Ever wonder why compressed air gets cold? There is a slight cooling effect when air leaves a compressed air operated air knife as the air goes from high pressure to low pressure. Air flow is amplified as atmospheric air is entrained along with the compressed air but there is still a slight cooling effect. This cooling effect assist in helping to dry or set a coating once applied to the product to ensure an even finish. Pressure used is typically quite low at 20 to 30 PSIG and angle around 3 degrees against the flow of material.
Cooling of Material
As mentioned above, there is a slight cooling effect which helps when used to cool materials. But in addition to the cooling effect, the laminar flow and high velocity of the air produced by a compressed air operated air knife can “cut” through the boundary layer produced by heat generated in a hot target and help cool the material. The cooling occurs due to the wind chill effect. How fast the material can be cooled depends on several factors. The higher the initial temperature, the faster it will cool, and the rate of cooling will slow logarithmically as the material gets cooler. Dwell time is also important. It is no question that you need time to cool an object. So when cooling with an air knife the product should travel slowly. Alternatively you can use several air knives, one after the other, to have enough exposure or dwell time to blow on the product and cool. The angle of the set-up should again be about 3 degrees with pressure typically at 80 PSIG to get the optimum mass flow and velocity for cooling.
So whether drying, cleaning, controlling coating, setting a coating or cooling, compressed air operated air knives offer an economical and viable solution. To further reduce your compressed air energy consumption – don’t forget to check out this article!
Plastics, glass and other insulating materials generate a static charge when rubbed, cut, and stretched. Hot or warm plastics will generate a static charge as they cool. In many production processes this can cause any of the following problems:
Static charge will attract dirt particles. If the part needs to stay clean for further processing such as painting, coating or even just packaging, these particulates can be a major issue.
As the product moves along the manufacturing process, materials such as film may bend or warp due to static and cause jamming of machinery, and hence downtime.
If the static charge is high enough, it can cause sparks and discomfort or even harm to personnel working with the material that is statically charged.
For these reasons, static charge needs to be eliminated or at least reduced and controlled. So how does the static charge get generated in the first place? Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged.
The rubbing of certain materials against one another can transfer negative charges, or electrons. For example, if you rub your shoe on the carpet, your body collects extra electrons. The electrons cling to your body until they can be released. As you reach and touch your pet (which is being really mean!) or perhaps a door knob, you get a shock. This same process occurs in a production line.
There are two ways to address a static charge. One is with a passive static eliminator and the other is with an active static eliminator.
Passive Static Eliminator
Some Passive static eliminator examples include: Copper Tinsel, Nylon Brushes, Sharp Edged Metal Strips, Antistatic Flexible Rope and Anti-Static Spray. These passive devices usually only reduce the charge with the exception of antistatic spray. In some situations – a reduction in the static charge may be adequate, however there are limitation with these passive devices. For rope and tinsel, it can potentially be dangerous when they break off and also has the potential to fall onto the material being processed. Antistatic spray may not be used if the statically charged part cannot tolerate a liquid for any reason. Brushes are limited to slow moving and lower static charges – most commonly used with printers, fax machines, and elsewhere where static only needs to be reduced to avoid sticking of the sheets.
Using passive static control may help in preventing some machine jamming and address employee discomfort but because it does not eliminate static completely (except for antistatic spray) it will usually not be enough to address dirt problems caused by static. Sprays have the disadvantage of being an endless consumable and an on-going cost that can add up over time. If the charge is very high, a passive device may knock the charge down to an extent but still leave a very high static charge that needs to be further addressed. This is when active static elimination is needed.
Active Static Eliminator
Active static eliminators (static bars or ionizing bars) are electrically operated and can be either AC or DC systems. DC systems are designed to work farther away from the target but are usually more costly than AC systems. On the other hand, AC systems normally work close to the statically charged product to remove the static charges. That being said – a more powerful AC system such as the Haug VS bar offered by Nex Flow is available which works at a further distance depending on the speed of the target. Active systems essentially ionize the oxygen molecules of the surrounding air which get attracted to the charged surface, thereby neutralizing the charge that the air “sees” (come in contact with).
Active systems work by generating alternatively a negative and then a positive charged ion. Whatever the charge on the surface is, the oppositely charged ion will remove it. Active systems can remove almost, if not all the static charge from the surface of a statically charged part. There needs to be an adequate number of ions for the level of charge needed to be addressed as well as some dwell time over the charged area. The faster the target moves the less dwell time is available for the static eliminating ion to remove the static charges. So for fast moving materials, you need a more powerful static bar – either high powered AC system or a powerful DC bar. Keep in mind that the distance from the target also matters. The further the bar is positioned, the longer it takes for the ions produced to arrive at the target and as they travel some will recombine. The result is less concentrated eliminating ions reaching the target surface.
Combining an Air Knife to a Static Bar
One way to help make a static bar work further away is to push the ions with either low pressure compressed air or with blower air. There is a myth perpetrated by some companies that make air knives, claiming that you can remove static charge at a ridiculously large distance just by adding a compressed air operated air knife. This is not entirely accurate. It is true that compressed air operated air knife, being laminar will push the ions and have much less of a recombination of ions than pushing these ions with a turbulent flow, but some recombination will still occur. So the further away the static eliminator bar is placed from a statically charged target, more dwell time will be needed to remove the static charge.
The only way to address a very high static charge or a fast moving target at a great distance from the target is with a stronger static bar that produces more ions – not by just using a compressed air operated air knife. History has proven this. If a static bar works at a moderate distance to the statically charged surface, it will probably still work if the static bar is combined with an air knife, on a moderately charged surface and at moderate speed. But to truly eliminate static charge farther away or at high speed, you actually need a stronger AC bar or a DC bar, with or without an air knife.
The real purpose of an air knife, whether blower operated or compressed air operated is to clean the parts. Dirt particles that stick due to static charge cannot be blown off easily because they get attracted back to the surface, even if loosened by a blast of air. By combining a compressed air knife with a static bar (ion air knife), the ions that get pushed by the laminar air flow eliminate the static charge allowing the static particles to be easily removed. Once the static charge is gone, it takes very little energy to remove the particles, so the air pressure can be as low as 2 – 3 PSIG in many cases. Blowers combined with static bars also work but because of the nature of the air flow with blowers, they need stronger or double static bars to do the same job and should have a high mass flow. In many instances, if the air flow is intermittently used, the energy cost of a compressed air knife static systems to blower air knife static systems are about the same. The advantage of a compressed air versions is that it is much quieter, simpler, compact, and is less costly to install and maintain. Nex Flow offers compressed air operated air knife systems with standard as well as with extra powerful static bars.
Combining an Air Amplifier to a Static Bar
Another version combining compressed air with static control is using an annular compressed air amplifier with a point ionizer (spot ionizer). This produces a laminar cone of ionized compressed air to blow onto the charged surface. Some applications include neutralizing the inside of blow molded or injection molded containers to loosen and remove plastic pieces and strings inside due to cutting processes. Another application is to blow off plastic strings and pieces after a molding process form the mold itself. Again, all these particles stick due to static charge. Our Ion Blaster Beam is a point ionizer attached to a compressed air amplifier via a plastic attachment. The attachment should be plastic to avoid the grounding effect of metal that would reduce the effectiveness of the ions generated. This is one of the reason why our Ion Blaster Beam works up to 30% faster than competitive units of similar design but with metal attachment.
Manual Static Elimination
For manual static elimination, an anti-static air gun is best and for the same reason stated above. Dirt particles are not easily removed if they stick to the surface due to static. Only by removing the static charge can a surface be cleaned. As with air knives and with the annular amplifiers combined with a static eliminator, once the air from an anti-static air gun neutralizes the charge on the part, particles can be blown off with minimal pressure and minimal compressed air consumption.
In summary
There are passive and active static control systems. Active static control is the only means to eliminate static charge completely and not adversely affect the end product. If the static elimination system is far from the statically charged target, or if the target is fast moving, or has a very high static charge, you need to use a more powerful static eliminator or increase dwell time.
The main application for using compressed air knives and amplifiers with static eliminators is more so for cleaning the charged surface and less so for pushing the static eliminating ions. That said, compressed air knives and amplifiers with static eliminators can be used at very low pressures and, especially when used with on-off control the energy cost is comparable to using blower systems. The advantage is that compressed air operated static eliminators are low cost, compact, quiet, simple and easy to use with minimal maintenance.
For manual cleaning operations an anti-static air gun is ideal and can save a great deal of energy because you can clean with less pressure than using the air gun solely.
When utilizing a static bar with a compressed air operated air knife, the further you are away increases the time needed for static charge removal so you may need a stronger static bar if dwell time is inadequate (high speeds) or the static charge is very high.
Nex Flow Air Products Corp. specializes in the use of compressed air technology for cleaning, drying, blow off, cooling and moving with the goal of svaing energy, and optimizing compressed air use efficiently and effectively. Also offer other specialized technologies related to compressed air use.
Questions may be submitted on the any application you may have or planning in the use of compressed air.
