Steve Katz, Editor01.25.16
Static electricity results when two or more surfaces are in intimate contact with each other and are then separated. In the label converting workflow, with rolls of stock becoming unwound and processed through a web, two surfaces are perpetually contacting and separating, hence, static is a constant – and something that must be kept in check.
Explaining the science behind static electricity, Matt Fyffe, vice president and general manager for Meech USA Inc., says, “Static arises when an external force causes an electrical charge to move from one material to another, leaving one positively charged and the other negatively charged. Speed and force of the friction, pressure and separation are all factors that contribute to the size of the charge, with increased force or faster processes leading to larger charges being generated. If one of the materials is conductive, it won’t hold the charge, but if the material is non-conductive the charge is unable to move across the surface, creating a static ‘pool’ of electrical charges.”
Brian Farno, application engineer manager at Exair Corporation, says static electricity occurs most often on the surface of non-conductive materials, but can also occur on ungrounded conductive surfaces. “A static (non-moving) electric charge is created whenever two surfaces come into contact and separate, or when friction occurs between them. When two materials are in contact, electrons may move from one material to the other. Material atoms with weakly bound electrons tend to lose them, while material atoms with sparsely filled outer shells tend to gain them. This is known as the triboelectric effect. When the materials come in contact, are separated or have friction between them, they retain this charge imbalance.”
Static electricity presents multiple challenges to label printers and converters, as electrostatic charges develop on the surfaces of webs as they are transported through various converting processes such as printing, rewinding, slitting, coating and laminating.
Kim West, marketing director at Simco-Ion, stresses that in addition to static causing detrimental effects to a print run, the phenomenon also presents a safety issue. She says, “The charges often cause contamination to the web material and defects in printing and coating uniformity, resulting in quality problems and customer dissatisfaction. Significant charges can also cause electrostatic shock to personnel or could even ignite vapors in solvent-based inks.”
An ever-present problem
Static Electricity can hinder a label converter’s process in many ways.
West points out that static charges are created and present during both the printing and finishing processes, and as little as 1,000-1,200 volts can attract contamination. “The substrate path on web presses, at each print station, can pass very close to the floor and this is where debris could be picked up and cause print defects. Incorporating static bars at each print station will help control static and lower the chance of contamination.
“Depending on the substrate, a static charge may start at the unwind and will continue all the way through the press to the winder many times, accumulating static charges unless neutralized. High static charges attract particulates and debris from several feet away to the web, resulting in poor print quality and other issues,” West says.
“In many cases a static charge will come in on the label or web stock and present issues such as misfeeds or shocking the operator as they are loading and unloading the material,” says Farno. “During the printing process, static electricity can cause spider webbing in the ink or repel the ink and keep it from reaching the label surface. When static causes freshly printed material to cling to another surface, it could smudge the image.”
Converting labels to a different length or width can also be problematic. “Slitting and cutting operations can generate a static charge, causing dirt to cling on labels, improper feeds and jamming, or labels and webs not being cut to correct lengths because they hang up in the cutting area,” Farno says.
According to Matt Fyffe, with the narrow web label industry’s stringent demands for high quality, controlling static is of paramount importance. He says, “Uncontrolled static can cause products to misbehave – print can be out of register, tiny holes appear in extruded film, and static charges can cause blockages in the most modern machinery – but dust attraction is arguably the biggest issue in a sector concerned with quality control, as airborne particles are attracted to charged surfaces, leading to high reject rates.”
Faster speeds = more static
Static and high-speed webs go hand in hand. “Today’s lines are capable of running at upwards of 1200 fpm, and we’ve noticed within the digital print sector that inkjet is evolving at a remarkable pace and its potential for increased speed and ever higher print quality is almost certain to continue,” Fyffe says. “However, with greater speeds come more static charges on filmic materials, which in turn will attract a higher degree of contamination to the web’s surface. Digital printers are especially susceptible to static, as it directly affects the print quality. A high charge on the substrate can repel or prematurely attract the ink being laid down by the printhead. This means that print quality and product cleanliness will become an even bigger concern and thorough anti-static and web cleaning solutions will be a necessity.”
Exair’s Farno agrees that digital printing has presented some hurdles due to the increased speeds of printing, as well as the ink being cured by UV lights. “If there is a large static charge on a surface, it will take a fraction of a second longer to dissipate the charge,” he explains. “If the machine is running at full speed, then the fraction of a second may mean the entire charge isn’t eliminated before the ink is applied. This can cause the spider web effect on the ink before it is cured. The other static hurdle created is due to the UV lights that are used for curing. This will decrease the relative humidity in the material as well as the area, which, in turn, increases the potential for static charge. Both of these hurdles create a need for a static eliminator that is not only fast but can eliminate static from a distance.”
Materials Matter
Label material, substrates, inks, constructions, and even types of printers and converters play a factor in the level of static charge that might be generated.
“When you add in the range of substrates now available, there are a variety of potential production problems that need to be considered. Lightweight substrates such as PET, PVC and Mylar are especially vulnerable to the effects of static,” Fyffe says.
Of all of the variables at play, according to Farno, the label material and substrate play a particularly critical role in the process. “Some labels don’t want to separate from the substrate due to a large static charge, while other labels repel from the product they are being applied to because both the label and the product have a large static charge of the same polarity. No matter what the material, ink type or construction is, static can virtually always be eliminated at the point it causes an issue with the use of an active static eliminator,” Farno says.
Simco-Ion’s Kim West emphasizes how today many industrial materials are utilizing insulators, such as plastics. “Their desirable qualities make them essential to use, however, they are likely to become electrostatically charged during processing,” she says, adding, “one of the largest and most consistent trends in the labeling industry is the utilization of flexible film-based materials. Additionally, label and packaging converters are looking for ways to increase line speeds. The use of plastics coupled with increased speeds escalates the chances of contamination being drawn to the production process. Unmanaged static electricity during the process can lead to a variety of issues. For many, understanding where static is generated is the key to success. Therefore, the need for monitoring the static environment is becoming more and more critical. Many industries and applications are requiring a cleaner and high-quality finished product; thus, a newer static neutralization system is a necessity to remove contaminants and understand your specific needs,” West says.
Matt Fyffe of Meech notes that the increasing use of metalized films and coatings in high end labels has affected the use of static control equipment. “The use of conductive inks and films creates its own set of challenges in controlling static charges, as the old standard ‘cookie cutter’ methods of static control don’t always work with these materials,” he says. “There needs to be more dialogue between the label maker and the static control provider in order to find the most appropriate solution. Fortunately, there are new static control systems that allow for adjustability and feedback controls.”
Static Solutions
Simco-Ion’s IQ Power Static Neutralizing System is a multi-patented lineup engineered to include IQ Easy sensor technology, bringing monitoring intelligence with a user friendly interface.
“IQ Power is ideal for label converters who need smarter, more integrated, yet easy-to-use solutions to controlling static issues. There is no complicated software to install or maintain,” West says. “Our Sensor Bar is an active multi-point sensor bar that offers standalone monitoring or closed-loop feedback functionality that works in conjunction with our static neutralizing bars. It adjusts as needed in real time to ensure you are receiving the lowest possible residual charge. The distinctive design allows for various configurations, allowing the ability to position the sensors across the target to receive a complete understanding of any electrostatic charge issues unique to the application. And with our ‘smart addressing’ technology, new sensor bars can be added in no time.”
Simco-Ion also offers its IQ Power Nozzle, a shockless pulse DC ionizer that is compatible with the IQ Power Static Neutralizing System. West explains, “When used with the IQ BPS Power Supply, users of the IQ Power Nozzle have worry-free, one-touch setup and continuous active monitoring. The IQ Power Nozzle functions with or without air and its compact size allows for neutralizing surfaces in a variety of applications.
“If the preferred method for the removal of debris is contact cleaning, the Teknek NWP is specifically designed for label and narrow web applications. With the exclusive Teknek cleaning core, this machine cleans with optimum performance. It has been specifically designed to remove dry unattached particles from labelstock and all other moving narrow web material. The uniquely formulated elastomer rollers efficiently control contamination, and the built in static bar further eliminates static charges created from a web passing through the rollers. Teknek rollers are also available silicone-free. Teknek is ISO certified for increased confidence in safety, reliability and quality,” says West, adding, “For applications where there is heavy contamination or contact is not desired, the V-Force 30 narrow web cleaner is our most innovative narrow web vacuum system, coming soon in 2016.”
Matt Fyffe says that in order to deal with such varying degrees of dust, a non-contact web cleaner like Meech’s CyClean proves to be an ideal solution, as the system performance is not affected by the contamination level and no consumables are required. “This helps reduce ongoing costs,” he says. “Designed for the narrow web industry, the CyClean is capable of removing contamination to below 1 micron, as well as incorporating fluid dynamic principles to deliver higher levels of cleanliness for label printing applications.”
While the web cleaner provides a solution for contamination on the substrate, there is also the necessity to eliminate the presence of static on the web, which may re-attract dust to its surface. Fyffe says, “Active static control utilizes ionization technology, employing high voltage AC or ‘pulsed’ DC to produce ionized air to neutralize surface charges. Recently launched static control bars, such as Meech’s Hyperion range, have marked a transition from AC systems to 24v integrated power supplies, providing more efficient ionization.”
Fyffe adds that long range ionizing systems achieve great static control in general applications, whereas for short to medium range applications (with target distances varying between 2-20"), plug-and-play bars are better suited. “The Hyperion bars are more resilient to the build-up of contamination which occurs during their use and also allow for easier cleaning, while their improved shockless design makes them safer for operators to handle,” he says.
Exairs’s Super Ion Air Knives and Ionizing Bars are the company’s most popular solutions for the static control problems of label and narrow web converters. Farno says the advantage to using the Exair Super Ion Air Knives is in how they utilize a laminar flow of compressed air to deliver a mixture of positive and negative ions onto the surface of the web or label.
“This ‘sheet’ of air will eliminate static charges on any surface it touches. This would generally blow the air against the travel direction of the material, which means the static-eliminating stream of air will continue to knock down the static charge further upstream alleviating the static problems sooner,” Farno explains. “Ionizing Bars are great for applications where compressed air is not available. They can eliminate a static charge from up to 2" away from the surface and come in stock lengths from 3" to 108". These products are small and lightweight, so attaching them to traversing printheads or fitting them into a tight space is possible.”
Explaining the science behind static electricity, Matt Fyffe, vice president and general manager for Meech USA Inc., says, “Static arises when an external force causes an electrical charge to move from one material to another, leaving one positively charged and the other negatively charged. Speed and force of the friction, pressure and separation are all factors that contribute to the size of the charge, with increased force or faster processes leading to larger charges being generated. If one of the materials is conductive, it won’t hold the charge, but if the material is non-conductive the charge is unable to move across the surface, creating a static ‘pool’ of electrical charges.”
Brian Farno, application engineer manager at Exair Corporation, says static electricity occurs most often on the surface of non-conductive materials, but can also occur on ungrounded conductive surfaces. “A static (non-moving) electric charge is created whenever two surfaces come into contact and separate, or when friction occurs between them. When two materials are in contact, electrons may move from one material to the other. Material atoms with weakly bound electrons tend to lose them, while material atoms with sparsely filled outer shells tend to gain them. This is known as the triboelectric effect. When the materials come in contact, are separated or have friction between them, they retain this charge imbalance.”
Static electricity presents multiple challenges to label printers and converters, as electrostatic charges develop on the surfaces of webs as they are transported through various converting processes such as printing, rewinding, slitting, coating and laminating.
Kim West, marketing director at Simco-Ion, stresses that in addition to static causing detrimental effects to a print run, the phenomenon also presents a safety issue. She says, “The charges often cause contamination to the web material and defects in printing and coating uniformity, resulting in quality problems and customer dissatisfaction. Significant charges can also cause electrostatic shock to personnel or could even ignite vapors in solvent-based inks.”
An ever-present problem
Static Electricity can hinder a label converter’s process in many ways.
West points out that static charges are created and present during both the printing and finishing processes, and as little as 1,000-1,200 volts can attract contamination. “The substrate path on web presses, at each print station, can pass very close to the floor and this is where debris could be picked up and cause print defects. Incorporating static bars at each print station will help control static and lower the chance of contamination.
“Depending on the substrate, a static charge may start at the unwind and will continue all the way through the press to the winder many times, accumulating static charges unless neutralized. High static charges attract particulates and debris from several feet away to the web, resulting in poor print quality and other issues,” West says.
“In many cases a static charge will come in on the label or web stock and present issues such as misfeeds or shocking the operator as they are loading and unloading the material,” says Farno. “During the printing process, static electricity can cause spider webbing in the ink or repel the ink and keep it from reaching the label surface. When static causes freshly printed material to cling to another surface, it could smudge the image.”
Converting labels to a different length or width can also be problematic. “Slitting and cutting operations can generate a static charge, causing dirt to cling on labels, improper feeds and jamming, or labels and webs not being cut to correct lengths because they hang up in the cutting area,” Farno says.
According to Matt Fyffe, with the narrow web label industry’s stringent demands for high quality, controlling static is of paramount importance. He says, “Uncontrolled static can cause products to misbehave – print can be out of register, tiny holes appear in extruded film, and static charges can cause blockages in the most modern machinery – but dust attraction is arguably the biggest issue in a sector concerned with quality control, as airborne particles are attracted to charged surfaces, leading to high reject rates.”
Faster speeds = more static
Static and high-speed webs go hand in hand. “Today’s lines are capable of running at upwards of 1200 fpm, and we’ve noticed within the digital print sector that inkjet is evolving at a remarkable pace and its potential for increased speed and ever higher print quality is almost certain to continue,” Fyffe says. “However, with greater speeds come more static charges on filmic materials, which in turn will attract a higher degree of contamination to the web’s surface. Digital printers are especially susceptible to static, as it directly affects the print quality. A high charge on the substrate can repel or prematurely attract the ink being laid down by the printhead. This means that print quality and product cleanliness will become an even bigger concern and thorough anti-static and web cleaning solutions will be a necessity.”
Exair’s Farno agrees that digital printing has presented some hurdles due to the increased speeds of printing, as well as the ink being cured by UV lights. “If there is a large static charge on a surface, it will take a fraction of a second longer to dissipate the charge,” he explains. “If the machine is running at full speed, then the fraction of a second may mean the entire charge isn’t eliminated before the ink is applied. This can cause the spider web effect on the ink before it is cured. The other static hurdle created is due to the UV lights that are used for curing. This will decrease the relative humidity in the material as well as the area, which, in turn, increases the potential for static charge. Both of these hurdles create a need for a static eliminator that is not only fast but can eliminate static from a distance.”
Materials Matter
Label material, substrates, inks, constructions, and even types of printers and converters play a factor in the level of static charge that might be generated.
“When you add in the range of substrates now available, there are a variety of potential production problems that need to be considered. Lightweight substrates such as PET, PVC and Mylar are especially vulnerable to the effects of static,” Fyffe says.
Of all of the variables at play, according to Farno, the label material and substrate play a particularly critical role in the process. “Some labels don’t want to separate from the substrate due to a large static charge, while other labels repel from the product they are being applied to because both the label and the product have a large static charge of the same polarity. No matter what the material, ink type or construction is, static can virtually always be eliminated at the point it causes an issue with the use of an active static eliminator,” Farno says.
Simco-Ion’s Kim West emphasizes how today many industrial materials are utilizing insulators, such as plastics. “Their desirable qualities make them essential to use, however, they are likely to become electrostatically charged during processing,” she says, adding, “one of the largest and most consistent trends in the labeling industry is the utilization of flexible film-based materials. Additionally, label and packaging converters are looking for ways to increase line speeds. The use of plastics coupled with increased speeds escalates the chances of contamination being drawn to the production process. Unmanaged static electricity during the process can lead to a variety of issues. For many, understanding where static is generated is the key to success. Therefore, the need for monitoring the static environment is becoming more and more critical. Many industries and applications are requiring a cleaner and high-quality finished product; thus, a newer static neutralization system is a necessity to remove contaminants and understand your specific needs,” West says.
Matt Fyffe of Meech notes that the increasing use of metalized films and coatings in high end labels has affected the use of static control equipment. “The use of conductive inks and films creates its own set of challenges in controlling static charges, as the old standard ‘cookie cutter’ methods of static control don’t always work with these materials,” he says. “There needs to be more dialogue between the label maker and the static control provider in order to find the most appropriate solution. Fortunately, there are new static control systems that allow for adjustability and feedback controls.”
Static Solutions
Simco-Ion’s IQ Power Static Neutralizing System is a multi-patented lineup engineered to include IQ Easy sensor technology, bringing monitoring intelligence with a user friendly interface.
“IQ Power is ideal for label converters who need smarter, more integrated, yet easy-to-use solutions to controlling static issues. There is no complicated software to install or maintain,” West says. “Our Sensor Bar is an active multi-point sensor bar that offers standalone monitoring or closed-loop feedback functionality that works in conjunction with our static neutralizing bars. It adjusts as needed in real time to ensure you are receiving the lowest possible residual charge. The distinctive design allows for various configurations, allowing the ability to position the sensors across the target to receive a complete understanding of any electrostatic charge issues unique to the application. And with our ‘smart addressing’ technology, new sensor bars can be added in no time.”
Simco-Ion also offers its IQ Power Nozzle, a shockless pulse DC ionizer that is compatible with the IQ Power Static Neutralizing System. West explains, “When used with the IQ BPS Power Supply, users of the IQ Power Nozzle have worry-free, one-touch setup and continuous active monitoring. The IQ Power Nozzle functions with or without air and its compact size allows for neutralizing surfaces in a variety of applications.
“If the preferred method for the removal of debris is contact cleaning, the Teknek NWP is specifically designed for label and narrow web applications. With the exclusive Teknek cleaning core, this machine cleans with optimum performance. It has been specifically designed to remove dry unattached particles from labelstock and all other moving narrow web material. The uniquely formulated elastomer rollers efficiently control contamination, and the built in static bar further eliminates static charges created from a web passing through the rollers. Teknek rollers are also available silicone-free. Teknek is ISO certified for increased confidence in safety, reliability and quality,” says West, adding, “For applications where there is heavy contamination or contact is not desired, the V-Force 30 narrow web cleaner is our most innovative narrow web vacuum system, coming soon in 2016.”
Matt Fyffe says that in order to deal with such varying degrees of dust, a non-contact web cleaner like Meech’s CyClean proves to be an ideal solution, as the system performance is not affected by the contamination level and no consumables are required. “This helps reduce ongoing costs,” he says. “Designed for the narrow web industry, the CyClean is capable of removing contamination to below 1 micron, as well as incorporating fluid dynamic principles to deliver higher levels of cleanliness for label printing applications.”
While the web cleaner provides a solution for contamination on the substrate, there is also the necessity to eliminate the presence of static on the web, which may re-attract dust to its surface. Fyffe says, “Active static control utilizes ionization technology, employing high voltage AC or ‘pulsed’ DC to produce ionized air to neutralize surface charges. Recently launched static control bars, such as Meech’s Hyperion range, have marked a transition from AC systems to 24v integrated power supplies, providing more efficient ionization.”
Fyffe adds that long range ionizing systems achieve great static control in general applications, whereas for short to medium range applications (with target distances varying between 2-20"), plug-and-play bars are better suited. “The Hyperion bars are more resilient to the build-up of contamination which occurs during their use and also allow for easier cleaning, while their improved shockless design makes them safer for operators to handle,” he says.
Exairs’s Super Ion Air Knives and Ionizing Bars are the company’s most popular solutions for the static control problems of label and narrow web converters. Farno says the advantage to using the Exair Super Ion Air Knives is in how they utilize a laminar flow of compressed air to deliver a mixture of positive and negative ions onto the surface of the web or label.
“This ‘sheet’ of air will eliminate static charges on any surface it touches. This would generally blow the air against the travel direction of the material, which means the static-eliminating stream of air will continue to knock down the static charge further upstream alleviating the static problems sooner,” Farno explains. “Ionizing Bars are great for applications where compressed air is not available. They can eliminate a static charge from up to 2" away from the surface and come in stock lengths from 3" to 108". These products are small and lightweight, so attaching them to traversing printheads or fitting them into a tight space is possible.”