Slitting Pretty
Options abound for printers seeking to bring the slitting department up to par with newer presses and other primary equipment.
by Susan Friedman
When it comes to equipment upgrade priorities, package printers have traditionally pushed slitters toward the back of the line. Technology is now in place to end productivity imbalances caused by using older slitters with more advanced pressroom machinery.
"The slitting department has become a bottleneck because slitting equipment made in the 1960s has stayed in use while presses, laminators and other equipment are being updated," observes Randy Wolf, sales manager at Titan Converting Equipment, Cumming, GA.
On-par productivity
Advanced slitter productivity features are within financial reach for converters because a single investment will buy multiple-machine capacity. One newer slitter achieving speeds of 1500 fpm is a potential replacement for three older slitters running at 500 fpm, Wolf contends.
Slitting's speed emphasis is paralled by the focus on maximized uptime. Wolf relates many converters are asking for differential rewind air shafts, a technology "still in the toddler stage" that will decrease downtime between slitting jobs, by eliminating shaft handling and adjustments to quick-locks and other devices.
Automation, of course, continues to reign supreme as the underlying efficiency vehicle. "Automation has been the key word in slitting for three or four years, with emphasis on more electronics, more measuring devices, less labor-intensive machinery and maximized productivity with a minimum of employee training," states Jerry Sellers, president of Burris Machinery, Hickory, NC.
Slitting is also achieving a more favorable place on the process line. Don Klein, western regional manager for Camas, WA-based Tidland, notes slitting is becoming more productive as it is more often seen in-line. This trend goes hand-in-hand, he notes, with slitting suppliers' increased interaction with press suppliers at the OEM stage, and the increased number of presses being supplied with video inspection equipment that facilitates on-line print quality monitoring of slit rolls.
In making a determination as to whether to slit in-line or off-line, Klein advises converters to consider how much the slitter set-up will slow them down. Long-run jobs with few changes are the best in-line slitting candidates, he notes.
The productivity of slitting itself is buoyed by sleeker approaches to supporting components and operations. Titan's Wolf explains more sophisticated handling equipment can strip, reorient, and stretch-wrap finished rolls and then place them immediately onto a pallet. Burris' Sellers cites a trend toward larger master rolls that reduce labor simply because they run longer.
Haste without waste
To prevent the quality of a finished slit roll from becoming lost in the flurry of faster, more efficient operations, suppliers offer waste-saving materials and monitoring strategies.
Wolf highlights PLC-programmed digital drives that allow smoother "soft-start" material transitions on unwind and rewind operations. In addition, newer software allows slitting operations to be hooked up to a modem for trouble shooting, and can maintain a history of any job from the master roll down to the finished roll, he says.
Tidland's Klein emphasizes automatic knife positioning as "a must" for printers of four-color process work who can't afford slitting errors on higher-cost materials. He cites shear slitting with a pair of circular knives as a higher-quality route. The knives are more expensive than razor blades, but last longer due to their scissor-like, self-sharpening capabilities—a particular benefit to industries needing dust-free packages, such as food and medical industries, he says.
Quality must also shine through increasingly broad roll-size parameters. "We are seeing and responding to requests for ever-increasing finished roll diameters, the capacity to accurately slit narrower widths with good and consistent roll density and wound in tension at maximum speeds," states Bob Preddy, vice president of sales at Webco Engineering, Westboro, MA.
Hands-on, hands-off safety
Slitting has made leaps and bounds of progress in the safety department—producing a generation of extremely sensitive equipment that will respond to the slightest possibility of injury. According to Scott Beaudoin, vice president of marketing at FlexoExport, Trumbull, CT, "Hands-off slitting operations are a major safety innovation. You can't get near a machine without breaking a light source that cuts off the power."
U.S. slitter suppliers appear poised to devote an even bigger chunk of resources to safety's cause. Beaudoin explains that it currently costs significantly more to build a slitter to European safety standards, but a universal safety standard may be in place by 2000 that brings everyone up to the same, higher level of financial commitment.
Safety enters the crucial zone in slitter rewinder areas that are not yet automated and require operator access. Webco's Preddy highlights the slitting section, commenting that "although automation in this area is becoming more cost-effective, many users are and will, for some time, be making manual settings and adjustments in this area." Current safety aids include improved pneumatic knife shafts and top knife holders, on-machine measurement with or without digital readout, and the ability to change or replace bottom knives quickly and efficiently, without the need to remove shafts, he says.
Blade selections can increase or decrease injury prospects. Jeff Epstein, president of Houston-based Ceramic Technologies, says slitting with standard steel razor blades is very common because of easy set-up, but ceramic coated steel razor blades stay sharper longer, offering a safer alternative. He elaborates that a ceramic coated blade will last 8 to 12 times longer than standard steel blades, staving off injuries with less frequent changes or positioning. Ceramic blades can cost $2 per blade compared to 25 cents per blade typically for steel, a higher cost offset by downtime savings, he notes.
Safety issues may also have sidelined laser slitting, an often-talked-about advance that thus far hasn't proved feasible for the majority of users. "I believe many obvious safety concerns will need to be satisfied prior to the serious consideration of laser slitting in the near future," comments Webco's Preddy.
"For years we've heard laser slitting is taking over, but we just haven't seen it," remarks Burris' Sellers. "Yes, lasers can cut almost any material, but the technology costs more and requires more people to run."
