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Before the print industry moved inexorably towards digital methods of printing, the problem of spine cracking wasn’t so obvious. Because letterpress and offset inks penetrate the paper, any paper cracking that happened when a sheet was folded wasn’t very obvious. Although spines were observably fluffy, they were still coloured the same as the print and only an up-close examination would reveal that the paper fibres had cracked when folded.

However, a raft of industry trends combined to change all that. For a start, the rising costs of labour throughout the 1990s, coupled with the simultaneous decrease in the print industry’s pool of skilled labour and several steep rises in business rates for factories, caused problems for creasing platens and cylinders. These machines, that had formerly carried out creasing as a separate process before sending the sheets on to a folder or a binding line, came under pressure to justify their floor space, labour and skill requirement. In the 20-odd years since then, many a creasing platen or cylinder has been replaced by a scoring device on the cover-feeder of a bindery line.

But perhaps the biggest driver for change came when colour digital print arrived on the scene in the early 1990s. Digital presses’ toner, and even the liquid ink used by HP’s Indigo digital presses, doesn’t penetrate the paper to the same extent as offset litho inks and instead sits on the surface of the sheet, meaning that any split paper fibres show as ugly white gashes along a fold-line. And the fibres in a digitally printed sheet are even more likely to crack than an offset-printed sheet, because the chances are that the digital sheet has been through one or more sets of fuser rollers, whose pressure and heat combine to make the fibres more brittle and hence more vulnerable to cracking to begin with.

A quick solution
Almost overnight, it became imperative that the industry found a solution to the problem of spine cracking. At that time, many printers and trade finishers turned to scoring as a solution, feeding their covers through otherwise-empty saddle-stitchers, perfect binders or folding machines, just to affect a pre-stressed line that would lend itself to crack-free folding. But the solution was short-lived. Scoring devices fitted to bindery lines mainly work on the principle of dragging a sharp blade along a fold-line and cutting into the fibres – so subsequent folding of pre-scored documents only made the fibre-cracking problem worse.

Fuelled by the industry-wide demand for quick, easy creasing that didn’t take up too much floorspace, post-press manufacturers set themselves to the task of designing creasing machines for the new millennium. The first arrived in the form of Morgana’s Autocreaser, a stand-alone matrix creaser that was introduced at Drupa 2000. Following that, Italian firm Bacciottini launched its PitStop range of creasers, with automatic feed, again with a matrix architecture. Both creasers use a rise-and-fall principle, with male-female tooling.

Proving doubters wrong
This was the first time the matrix principle had been used in a machine so small and many platen-bred operators initially doubted the quality of crease that either the Italian or the British machine could produce. And plenty of detractors pointed out that the process was inherently slow. Although each machine can put up to nine (the Autocreaser) or 100 (the PitStop) creases in each sheet, the fact the sheet has to be stopped for each crease to be made slows the process down. Nonetheless, within these limitations – neither of which particularly works against the creasers in their target digital sector – the stand-alone creasers have, quite literally, made their mark and are now the accepted solution to the fibre-cracking problem in digital print.

Following the introduction of the matrix machines, creasing underwent its next revolution back in 2001, when Tech-ni-fold founder Graham Harris secured the first contract with a folding machine manufacturer to incorporate his creasing brainwave, dubbed the Tri-creaser.

The Tri-creaser came into being after Harris, former manager of the finishing department at a general commercial printer, observed both the problems with scoring and the unsatisfactory speeds of the rise-and-fall matrix mechanism. “The matrix machines were fine, but they were always going to be slow,” he says. “They work within digital because the runs are short and they don’t cost very much to buy or run. But there’s always a need to crease higher volumes and to
do so faster.”

The basic Tri-creaser mechanism works as follows: a pair of wheels that incorporate male-female tooling place a crease in a sheet without stopping it or even slowing it down. Simple, inexpensive and effective, it has since been bought by thousands of printers worldwide to add to their folding machines or bindery lines.

Continued success
The Tri-creaser success doesn’t stop there: manufacturers of post-press equipment are beginning to sign OEM deals with Tech-ni-fold to use the Tri-creaser wheels in their kit – typically to replace the scoring mechanisms that pre-score covers. Japanese post-press manufacturer Horizon now incorporates Tri-creaser wheels on its perfect binders and bookletmakers, while fellow Japanese corporation Duplo has invented several dedicated cutting-slitting-creasing lines that have the Tri-creaser mechanism at their heart.

Harris’s invention initially raised non-comprehending heckles across the industry. Because the male-female wheels look outwardly similar to the rotary scoring devices incorporated into folders, saddle-stitchers, perfect binders and bookletmakers, many printers have taken the Tri-creaser itself for a scoring device; a mistake compounded by an early joint venture between Tech-ni-Fold and French folder manufacturer Acson that saw the launch of a table-top auto-feed creaser known, confusingly, as the EasyScore.

By virtue of the fact that the Tri-creaser wheels run at the same speed as the sheet that passes between them, no drag effect is incurred and no paper fibres are broken. Instead, the male-female tooling presses a crease into the sheet in much the same way as a rise-and-fall matrix, but without the need to stop the sheet. Heavier stocks are creased by repeat wheel-sets positioned sequentially to effect a first crease and a second reinforcing crease along the same line. While the Tri-creaser mechanism is protected by several patents, the principle of rotary tooling (tooling incorporated into wheels) is not.

Another method of incorporating creasing into an existing print process is to run it on-press. This isn’t a new idea: printers have been buying perforating and cutting tooling for use on-press for years. But the idea recently took a technological leap forward with the involvement of German firm Cito, which in 2002 began to promote its RSP perforating, die-cutting and creasing system for use on an offset press. This was closely followed by the Perf-Print-Plus system manufactured by Swiss company PPP International, which works on similar lines: an arrangement of metal rules in a grid that locks to the cylinder of either the coater or the impression cylinder. Again, by adding the basic cut/crease/perforation functionality to an existing print process, Cito and PPP are effectively saving labour, skill, floor-space and costs for printers – as well as offering a quality of pre-stress device with superior results to scoring.

It looks as if scoring, with its fibre-damaging effects, is rapidly becoming a thing of the past in the print industry. “The only thing scoring had to commend it was that it was cheap,” says Graham Harris. “But now there’s an alternative to scoring that’s even cheaper and more effective.”

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HOW THEY WORK: CREASING AND SCORING
Scoring is the easier process to understand; it’s essentially the same thing as children do in school to make the fold in their Mother’s Day cards. But where they run the blade of a pair of scissors alongside a ruler, a modern scoring device drags a pointed metal blade along a scoring line. The blade cracks or cuts through the paper fibres on the surface of the sheet, creating a point of pre-stress so that when the sheet is folded, the fibres are predisposed to crack and, therefore, fold more easily along that line.

Where the creasing process differs from scoring is that with creasing, the fibres are not cracked by the movement of the creasing tool along the line; instead, they are pressed between a pair of male-female tools that indent the sheet. Like scoring, this creates a point of pre-stress, but the difference is that when the creased sheet is folded, its fibres do not crack, but instead retain their natural elasticity and bend while remaining intact.

Scoring has numerous disadvantages when compared to creasing. For a start, it actually damages the paper fibres by cutting them, which means that any document folded along a score-line is likely to fall apart faster than a creased document. Scoring knives on saddle-stitchers and digital presses are also often regarded as consumables and either need replacing or sharpening, at a cost; and a blunt scoring knife can also score a wider crack than is necessary, causing greater damage.

Feeding laminated covers through a pre-scoring device on a stitcher or digital press can also cause problems: a scoring knife will cut through the top layer of laminate film to score the paper fibres, and therefore makes the cover likely to delaminate.