Never Boring
Shorter runs—they are the reality for many package printers today. This reality can impact your slitters/rewinders by way of greater wear and tear, more frequent tool changes, and so on, but these are not the only packaging trends that affect the slitters/rewinders market. The myriad substrates available to converters alone impacts slitter/rewinder performance and construction. Thank the emergence of flexible packaging for the increased substrate requirements. All these factors will impact your business in terms of what equipment you buy—a typical rewinder versus a turret rewinder, for example—what you will do to increase the lifespan of such equipment, as well as what other types of web handling equipment you purchase.
Lifetime and wear and tear
According to Brian Ivens, manager, marketing and sales, ARPECO, a quality product designed for hard work over an extended period of time is a good start toward extending the life of your slitter/rewinder. Next, and everyone who contributed to this article agrees, ensure that the equipment is properly adjusted and maintained periodically. “Train operators on proper adjustment and use of the machine to eliminate undue wear,” says Ivens. “Utilize knowledgeable maintenance staff or factory-trained technicians to change wearing parts and make machine adjustments.” Doing so, says Ivens, will ensure proper performance and provide longevity to the life of the machine. Patrick Boshell, marketing manager for Rotoflex International, Inc., concurs. “Regular maintenance and operator training is important to maximize machine productivity. Simply put, “maintenance, PM, and maintenance, like every piece of equipment, if you take care of it, it will be reliable for an extended time,” says Wolfgang Ripper, Matik.
Ulrich Jorgens, product manager, Atlas/Titan slitters/rewinders, Bobst Group North America, adds that “a preventive maintenance program increases the lifetime substantially, but qualified opeators have the biggest impact.”
As far as wear and tear, slitters by their nature tend to wear out, simply by virtue of the job that they do. “Slitters and rewinders are meant to run at high speeds and typically cycle often, which [creates] wear and tear on acting parts such as clutches, brakes, nip rollers, motor drive systems, etc.,” says Ivens. “The trend [toward] shorter runs can cause the number of cycles to increase, but with periodic maintenance, slitters/rewinders will not suffer excessive wear and tear as a result of shorter runs.”
According to Darrel Spors, sales manager for Keene Technology, Inc., slitter blades have a definite lifespan when you consider the amount of material passing over them. Set-up and tear down also impact the wear and tear “more so on the slitter blades being repeatedly set up and torn down,” he says. “The more the components of the machine are changed out and moved around, the more chance they will wear and tear.”
“The sheer variety of label jobs forces machines to run at extremes, and as a result, machine components can be stressed and, as a result, fail,” says Jeff Feltz, director, product management, Mark Andy, Inc. “Today’s rewinders are also more complex, employing much more electronics than before.” As a result, according to Feltz, these machines run far better than their predecessors, but they also have many more sensitive components such as load cells, drives, touch screens, and so on. These components can and do fail. “Our engineers and support personnel work continually to improve the product life of our equipment through testing, design, and improved sourcing,” he says.
To extend the lifetime of your slitters and rewinders, Feltz suggests specifying equipment for future requirements as opposed to current requirements. By doing so, converters will prolong the useful life of their machines as substrates and applications change.
Again, preventive maintenance is key. “High-quality, new machinery that is maintained regularly by either factory-trained technicians or trained maintenance personnel will last for many years,” says Feltz. He also states that converters should insist on high-quality spare parts from the OEM or a reputable dealer.
Continuing development
As packaging continues to be the final straw in consumers’ buying choices, the demands placed on the equipment that produces the packaging will increase. Feltz states that modern slitters/rewinders must adapt to the demands of the short run label market—capable of quick changeovers with little or no scrap produced. “Our business has responded by developing rewinders that are capable of running a wide variety of substrates, are easier to set up, and produce less scrap on setup,” he says.
To Ivens, continuing development is natural. “I don’t expect that we will ever have a slitter/rewinder, or any other machine in the package printing and converting industry, that is perfect and will not continually require development. The current trends to shorter runs and thinner materials will be replaced by the next wave. I am just happy to be involved in such a dynamic industry that continues to be innovative and progressive in its thinking day after day, year after year. It will never be boring.” pP
Proper setup for quality cuts
Pete Ackerman, senior technician, slitting group, Tidland, suggests the following to ensure the effectiveness of your slitter/rewinder.
Air Pressure
Instrument quality air or the use of a low micron coalescing and particulate filter is required. This will keep the knifeholder in top condition from contaminants like water and oil. It is necessary to have enough pressure to penetrate the web and start the slit process, but not too great to jeopardize blade wear.
Overlap
Overlap, a potential hazard not only to blade life, can also jeopardize slit quality. It is estimated that for every 0.010 inch increase in overlap, the speed of the upper blade will decrease 1 percent. Also, the nip point will progress ahead of the anvil when the overlap is increased causing the paper to burst ahead, rather than being supported by the anvil prior to slitting.
Side-load
Correct side-loading of the upper blade accomplishes two things: the blade will shift away from the anvil blade prior to disengaging, and the upper blade is driven by the anvil.
Over-speed
Over-speed is used on tangent slitting only where the material contact to the blade is minimal. If you can be turning faster than the web, then the results of the cut will be much cleaner.
Grind Angle
Grind angle depends on the material being slit. Greater angles will allow a narrower contact of the blade into the web path, and will not disrupt the edge of the material.
Cant angle
In heavier stock, this angle is decreased to allow the denser material to pass the blade without slowing or stalling the blade from turning. In some instances, such as foil, a zero degree angle is used.