Sticking to Business

Suppliers continue to tweak splicing equipment for enhanced roll throughput and saleability.

by Susan Freidman

"Splicing technology is pretty straightforward," states Jerry von Gretener, sales manager at Advanced Web Dynamics, Bloomsburg, PA. He's not alone in his statement. Suppliers agree that a splice is well, a splice...and tape is tape. But subtle design and operation adjustments continue the progression of this finishing process.

According to "Herb" Herbert, president of West Caldwell, NJ-based CTC, specialists in narrow-web splicing equipment, the main goal of today's narrow-web splicing technology is refinement—polishing the design approach to higher line speeds, splice accuracy, splice mechanism technology and roll handling.

Electronic eye mechanisms used to locate splice marks along the register lines of preprinted material are another fine-tuning target. More converters are printing, rewinding and then taking the roll to a secondary process, so the splice mark detection process must be sped up to reduce storage needs, says David Wright, vice president at Martin Automatic, Rockford, IL.

Setting speed limits

Finding the most fitting splice configuration can depend on substrate properties and widths, as well as space and budget.

CTC's Herbert positions zero-speed splicers (as compared with the flying splice concept) as predominant in narrow-web, because they are the most flexible, can be designed as lap or butt splicers, have more accurate tension control systems, and in lap splice configuration produce much shorter tails.

Zero-speed splicing provides the utmost in control, agrees Martin's Wright, and is seeing a higher rate of success with different materials.The most difficult webs to splice are the weakest, such as half a mil thick films and foils, he adds, but zero-speed splicing's new lower inertia carbon fiber rollers can help by allowing tension as low as 8 lbs. across four meter-wide webs.

"Festoon, zero-speed systems tend to occupy more space," states Steve Carey, sales manager for Atlas Converting Equipment. He believes flying splicers offer the lowest-cost solution for medium webs 20˝ to 60˝, while zero-speed splicers provide better economics for narrow webs below 20˝. He gauges flying splicers as the most common choice for film and laminates, and sees frequent use of zero-speed with narrow-web paper, board and label stocks.

For profitability's sake, web ends must be joined in a manner that minimizes scrap and maximizes material performance. Herbert explains that butt splicers, which are an absolute requirement for pressure-sensitive webs, must produce a splice with zero gap and no overlap. In lap splicing, he explains, the splicing mechanism is less complex, since it is only required to apply splicing tape on one side of the web, and keeping the tail short is desirable but not as critical as with a butt splice.

Wright advises the lap-splice can produce undesirable results with thicker materials, such as 30 pt. to 40 pt. board, because the double thickness of the overlap may throw off subsequent operations.

A slightly more expensive splice configuration, according to Wright, is welded lap splicing for webs that will melt, such as polyethylene. The weld is often stronger than the material itself, he says, and the operator does not have to prepare the tape application. A welded butt splice can save even more product in the area of the splice.

Automatic or manual quality

For the quality splices that characterize a saleable roll, package printers can turn to both equipment advances and their operator's own two hands.

Chris Plude, engineering manager at Keene Technology Inc., South Beloit, IL, emphasizes automation. "Automatic zero-speed splicing equipment improves the alignment of the webs being spliced, and does not disturb the natural path of the web," he says.

This technology also applies the splice tape in an aligned and uniform manner, he explains, to more evenly distribute web tension and reduce the chance of the splice coming apart as it travels through the press, dryers, and die stations. It also permits a stronger splice with increased dwell time in adhering the splice tape to the web.

Suppliers have also turned their attention to more profitable quality control features. "Converters increasingly wish to sell good quality splices to their customers without removing the splice first," contends Atlas' Carey. "Improved web inspection systems allow first quality reels to be produced the first time around, but converters should keep in mind that the flying splice produces an inconsistent quality join which normally must be removed, whereas the zero speed option generates a consistent quality join with minimum or zero tail that can be passed on to the end-user."

Making splices ever-cleaner with zero tail on the unwind and zero foldover on the rewind is another current quality following, says von Gretener. Foldovers in particular can imprint and damage an entire roll of thinner film. Stationary knives are thus far the best solution to this challenge, he notes.

Sometimes, though, mere manual tweaking accomplishes quality best. "Lots of end-users will specify the number of splices they'll accept in a roll, and converters may have to make manual adjustments to the roll to ensure saleable, acceptable splices," von Gretener points out.

Flexible handling and placement

Roll handling options are fast extending beyond traditional shafts to cantilever shaft and shaftless designs. Cantilevered shafts eliminate the need for the operator to directly handle the shaft, while shaftless designs provide safety and ergonomic benefits by placing the lifting work on the unwind itself.

Shaftless designs can also provide a more forgiving handling approach. "With shaftless unwinds," explains KTI's Plude, "a roll shaft does not have to be run completely through the core, allowing easier loading of rolls with minor core deformations."

"Shaftless splicers can be convenient for roll loading," concurs Herbert, "but it is possible to run into problems with how much torque can be transmitted to the core with this design. In higher tension applications, an air shaft with multiple lugs, buttons or continuous leaves gripping the core through its entire length will transmit much higher torque to the unwinding roll."

Package printers seems to be enjoying a similar degree of flexibility in the placement of the splicing equipment itself. Plude projects that free-standing splicing equipment is currently more popular because "most press manufacturers do not build this type of equipment and it allows the end-user to select any vendor that may be preferred. It is also the most economical and timely when adding splicing equipment to a process."

Wright observes that mounted splicing machines, which can be positioned right on top of process lines, are seen most often on laminating lines. A more of-the-moment configuration for shorter printing lines, such as those for pressure sensitive labels, is a movable splicer mounted on casters.