A moving web will create static electricity under any conditions.
The presence of static can be a threat to safety as well as the cause of contamination and equipment malfunction. Removing static safely and effectively is easily accomplished with the right equipment.
By Jack Kenny
Meech 915 high intensity AC ionizing bar
The narrow web industry is paying more attention lately to static control, according to Matthew Fyffe, general manager of Meech Static Eliminators USA. “Narrow web converters haven’t always been at the forefront when it comes to static control, but because of competition we see more attention being paid to quality control. As web speeds get faster, they are using a lot more different materials and generating more static. Any plastic or material with a polycoating will generate more static charge. There are certain types of labels, such as styrene, that generate even higher charges.”
Wide web converters are more familiar with static issues, he adds, because of the higher speeds at which their presses traditionally perform. High performance static control equipment might not be needed in the narrow web shop because speeds are generally lower.
“That said, the old standby inexpensive hot or shockless bars are no longer powerful enough for narrow web,” Fyffe says. “Now they need high intensity, long range static bars. These are much more powerful than older bars, and can be positioned farther from the material. And they can utilize fewer bars than before to neutralize the charge.”
Older bars could manage static removal at up to about 300 fpm, and had to be located about a half-inch from the web surface. The new bars can operate at 2,000 fpm and can be positioned up to about six inches away from the web.
Fyffe says that static removal equipment these days isn’t always positioned at the unwind. “We have gotten away from trying to neutralize the charges everywhere, so we address it where it happens, at a print station or at the rewind. Sheeters can generate significant static charge, and we are seeing a lot with in-mold labels.”
The Meech static removal product popular among narrow web converters is the model 915 high intensity AC ionizing bar. “This one has a greater range, and can handle faster web speeds,” Fyffe says. The unit is shockless and provides effective ionization from up to six inches away.
“A lot of the action today is in the digital arena,” says Peter Mariani, president of Electrostatics, “in both variable data and short run, high graphics applications. Though it’s not as intimidating as more established printing technologies, it is certainly where a lot of the phone calls are coming from.”
The challenges with digital presses, Mariani says, “are that these are very precise pieces of equipment. Paper dust causes difficulties in these machines: It jams inkjets, affects print quality, and causes downtime. We have developed a new line of web cleaners – called AutoStat-D – specifically for digital presses. They incorporate our patented grooved face plate – which keeps paper out of the vacuum slot, allowing for loose web tension – as well as a small compressor in the dust collection system. A lot of digital press owners don’t have a compressed air source in their building, so this web cleaner comes with it.”
The AutoStat-D web cleaners are designed to fit continuous feed digital printing equipment from manufacturers such as Kodak, HP, Xerox, Canon, and Nipson.
Mariani says he hasn’t seen big problems with speed and static in the narrow web converting arena. “Speed is a factor, but materials are also important. Some will generate more charge. Paper typically is not that big a static generator. With coated and high gloss papers you get more charge. Plastic films and vinyls will have high charges.
“Relative humidity is a factor,” he adds. “At around 60 percent humidity most things in a room wet out. Below that, the less conductive a surface becomes and the more things behave like a nonconductor.” That’s when the static charge builds up.
Equipment these days has a lot more electronic components, says Mariani, making static removal imperative. “Static can build up and cause damage. It can get picked up by sensors, then go back to the controllers and blow them out. There are all kinds of sensors that the machine needs, and these are subject to damage due to static. They are also subject to confusion with dust buildup. Dust will be attracted to the electronic eyes and cloud the windows.”
Contamination is an operator issue as well, because it can have an impact on productivity. “Sometimes static will cause materials to wrap around rollers, or it won’t sheet properly, or it may not stack properly. If you are working on a high quality direct mail piece with inserts, for example, where you have to keep track of all material in sets, a jam or hang-up in the machine is detrimental to your productivity.”
Doyle focuses principally on web cleaning systems that utilize a variety of technologies, including static control, but it also markets the static control products of Meech Static Eliminators. One product that Doyle does manufacture is called Statikil, which comes in liquid or aerosol form for application to specific areas.
“In the printing market it is used if the converter is having feeding problems at the end of the press, static issues at the diecutter, sheeter or stacker,” says Mark Gibis, vice president of sales for Doyle Systems. “Instead of putting an active static elimination device in place there, if it’s only a temporary problem, the Statikil is a good solution. The liquid can be sprayed or added to another formulation.”
Doyle manufactures what it terms a multi-modal web cleaning system that utilizes four processes: active static elimination, heavy duty dual brushing action, high velocity dual air scrubbing action, and extreme vacuum. “We try to match the static elimination device to the application; it can be simple shockless bar for lower speed applications. Depending on the substrate and static readings, we will go to a higher intensity solution.” Brushing involves heavy duty nylon brushes to agitate and loosen debris. The air scrubbing uses a specially designed face plate that makes use of outside air.
Another technology incorporating static control is contact roll cleaning technology, which utilizes a tacky roll for collection of debris from surfaces. Doyle’s hybrid cleaning system is a combination of the multimodal vacuum based system first, then the contact roll cleaning system as a second cleaning unit. “It gives the customer two options,” says Gibis. “They can use them in combination to remove the majority of debris with vacuum, then finish with the roll cleaner for a fine cleaning finish. It’s really a high efficiency system.”
SIMCO’s PerforMAX IQ system
SIMCO recently launched its PerforMAX IQ closed loop ionization system, which has the ability to monitor static charge on the web downstream from the ionizer and display the information on a screen. The data feeds back to the ionizer and can adjust its performance, according to Jay Perry, marketing manager. The system is designed to efficiently neutralize electrostatic charges on films, paper, nonwovens, and fabric in web or sheet form, and also can be used for applications such as blow molding and injection molding.
“The PerforMAX IQ uses an entirely new static bar design utilizing emitter points constructed of special alloys for extended operation and to provide maximum neutralization of high static charges on high speed and distance applications,” says Perry. “The IQ bars include a unique connection design which enables the power supply to recognize the application requirement and automatically set the output power necessary for the installation. The PerforMAX IQ power supply is equipped with a single momentary push-button calibration design that simplifies the setup.”
Popular among narrow web converters is SIMCO’s R50 Blue Bar, which can handle web speeds up to 2,500 fpm.
“The biggest problems in the tag and label industry connected with static electricity are cleanliness, contamination control and operator safety,” Perry says. “With complex label structures, using coated papers and films, as the material travels through the press and gets charged it acts as a magnet and attracts particles. When that happens you have print quality issues.”
Perry also says that positioning of static removal devices is important. “Most often in a typical flexo press operation, there will be an ionizer and maybe a web cleaner right before the first print station to remove the static charge and clean particles off the web. Then there can be one or more ionizers positioned elsewhere in the process, depending on the number of colors that are set up.”
Static Clean International
“Static electricity is like gravity,” says Tim Rice, marketing director for Static Clean International. “It’s always going to be there.”
Static Clean manufactures static bars and static brushes. A static brush, says Rice, is a passive device “great for taking the static charge down to a certain point, but it still leaves about 1,000 volts behind, so it’s not perfect. If you want complete or close to complete static removal, go to a static bar.”
The company’s two most popular static bars in the narrow web field are the BR2200 and the BR4400. “The 2200 is a single bar that will work within two inches of the material. Once you go beyond that it starts to lose its effectiveness. The 4400 is a double bar with a more extensive range, and will work upwards of six to eight inches away from the substrate. The issue is how close you can mount on your press.”
The company also produces air tubes and air knives that will assist with the static removal and web cleaning. “These are air assisted ionizers, such as a 4400 with an air tube or a 2200 with an air knife. An air knife creates a blade of air that blows off not only particulate but also the electrons that cause the static.
MKS Ion Industrial
Ion Industrial introduced an “intelligent” static neutralizer in 1999 with its patented Virtual AC system, featuring a control module that displayed real-time feedback on system performance and diagnostics. In 2000, Ion Industrial unveiled a system with computer interface and dedicated software that allowed operators to monitor and control up to 31 individual static neutralizers connected in an integrated system. A Virtual AC system was then designed with performance monitoring and computer interface for use in hazardous areas.
In 2004 the Virtual AC became the first static neutralizing system with fieldbus communications for interfacing with industrial networks, according to the company. Today, Virtual AC static neutralizers are available with monitoring technology that can verify static charges before and after the point of neutralization.
Installation of Virtual AC equipment is simplified using compact, high voltage power supplies that are half the size of conventional power modules. These can be mounted directly on the bar or remotely nearby, minimizing or eliminating the need for high voltage cabling. The system’s plug-and-play design allows static bars to be daisy-chained together using a single Virtual AC solid-state power supply – ideal for narrow web converters requiring several points of static control.
Bars have been tested effective in neutralizing static charges up to eight inches away from webs moving at speeds of 2,500 fpm and higher, and up to 20" away on unwind and rewind installations. Static bars also can be remotely activated without turning off monitoring circuitry.
In 2006, Ion Industrial and another innovative static control manufacturer, Tantec Inc., became part of MKS Instruments, a worldwide provider of process control solutions for advanced manufacturing processes. MKS Ion Industrial is also a source of electrostatic “pinning” or “tacking” equipment used in card inserting, magazine/catalog stacking, chill roll pinning, in-mold labeling, interleaving, roll changeover/transfer, plastic bag manufacturing, binder manufacturing and shrink wrapping.