Finishing for digital books all sewn up

Nessan Cleary
Monday, March 20, 2017

There’s a consensus that the digital book printing market is growing, which of course means more demand for book finishing.

But of course there are lots of different types of books – from photobooks and corporate reports to manuals and catalogues – which come in different sizes, thicknesses and run lengths. There are also lots of bindery options, with varying degrees of automation, but no single process. 

There are two main choices: perfect binding or saddle-stitching. As a general rule, stitching tends to be the cheapest option and is mostly used for products with a short shelf life, such as magazines. Saddle-stitching is also very quick, which suits the high volumes associated with the magazines market.

Traditionally saddle-stitching involves taking a sheet of paper and folding it over, then folding a second sheet on top of that over a saddle and stitching them together. These days most saddle-stitchers fold a block of paper over and then staple the sheets together. Some systems use pre-formed staples but most use a drum of wire and pass the wire through the pages and cut it to length to form the staple. In the main, stapling machines are cheaper to buy and maintain but the consumable cost of the staples is much higher than a stitching system so the choice depends on volume. 

Jo Watkiss, marketing director for Watkiss Automation, points out that a stapling machine will use the same size staples for every book but that a stitching machine will use less wire for a thinner book. She adds: “We can get a perfectly formed stitch and close the ends which is unique to our machines.”

Watkiss’ main saddle stitching offering is the PowerSquare 244, which offers stitching, folding, spine forming and trimming. It can produce books up to 10.4mm thick, roughly 224 pages at 70gsm. It can form books with the appearance of a square spine, achieved by rolling the cover onto the book block, which looks similar to perfect binding. Watkiss adds: “It’s possible to count how many sheets are going in a book and adjust the stitching and folding to match the book thickness automatically.” Watkiss also sells the smaller PowerSquare 160, which does use staples.

watkiss-powersquare

Watkiss PowereSquare 244



Horizon makes the StitchLiner series of saddle stitchers. The StitchLiner 6000 can take books up to 10mm thick and produce 6,000 booklets per hour. It incorporates flat-sheet collating, scoring, folding, stitching and three-knife trimming in one line. There’s a touchscreen so that operators only have to input the sheet and booklet size and the system sets up each station automatically.

Duplo sells the iSaddle 2, a modular device available in several configurations, such as including a twin feeder. The iSaddle itself includes scoring, plough-folding, stitching and trimming. It can handle books up to 120 pages. 

Muller Martini makes several saddle stitching systems, including the Presto and Primera, modular systems that are both available in conventional and digital versions. The Presto II Digital system, for example, can handle books ranging from 1mm to 10mm at up to 9,000cph, with every book being different. The Primera MC Digital can handle 14,000cph with a variable page count from one book to the next.

Ibis Bindery Systems has taken a unique approach to saddle-stitching, developing its own ISG gluing system for its Smart Binder. Managing director John Cracknell explains: “We replace the wire stitching with little drops of cold glue between each sheet, which produces a very strong book that’s better for lay flat and for very thin books, and easy to operate.” The glue is applied as part of the plow-fold process and activated through pressure. The Smart Binder can be fitted with both a wire stitching head and glue applicator but Cracknell says that most customers just use the ISG glue. There’s also an option for perfect binding.

The Smart Binder can handle books from four to 200 pages and can dynamically adjust from the minimum to the maximum thickness from one book to the next. Cracknell says: “We designed it from the beginning to suit on-demand digital printing.”

It’s been designed for 24-hour production and can produce up to 7,000 saddle-bound books per hour. It can be used online and offline. 

Perfect binding

The main alternative to saddle-stitching is to use glue for perfect binding, which produces a very flat spine. This has the advantage that the book title can be printed on the spine so that when a series of books are stored vertically on a shelf it’s easy to pick out the one you want.

Jason Seaber, technical sales director for Intelligent Finishing Systems, says: “If it’s a book or booklet with 64 pages plus cover then generally it’s recommended to be saddle stitched because it will be flat and well presented. Above 64 pages we find that the book starts to gape a little bit and doesn’t look as neat. So anything over that we would recommend perfect binding rather than stitching.”

Hotmelt or PUR

There are two different types of glue: EVA, also known as hotmelt, and PUR, and each has its own distinct advantages. Hotmelt is much quicker as the glue dries immediately and the machines are much simpler, meaning cheaper, and easier to use. Hotmelt glue is ideal for on-demand fast-turnaround jobs, such as company reports. The glue is heated up and absorbs moisture from the pages, curing almost immediately as it cools down.

PUR glue, on the other hand, cures through a chemical reaction with the moisture content in the atmosphere. Seaber explains: “Generally PUR glue gives you a stronger bond and has the advantage that you don’t have to be concerned with things like grain direction of the pages or if the pages are flat or if it is a heavy paper.”

The PUR process can’t be undone by further heating but starts as soon as it is exposed to air. The glue will stick to anything so the storage tanks and applicators have to be teflon coated. It has to be stored in vacuum sealed tanks and operators have to be careful to only draw off the required amount.

Some perfect binders, such as Horizon’s BQ470, are designed to work with both types of glue. The BQ470 is a four-clamp machine that can handle books up to 65mm thick. However, Horizon showed off a new version, the BQ480, at the recent Hunkeler Innovation Days event. This gains more powerful stepping motors, which significantly increases milling, sizing, pressing and creasing. It can handle variable-data production down to a book of one as well as short runs with multiple thicknesses providing the books are the same size.

Bourg makes several perfect binders, with some using EVA and others PUR glue, as well as the BB3202, which works with both glue types. It includes a compiler that can collect the pages into a book block ready for binding. It can handle books from 1mm to 60mm and produce up to 285bph with PUR glue, or 350bph with EVA. 

Duplo makes a number of perfect binders, including the PFi Bind 6000 series of automatic single clamp machines. This is capable of inline scoring and cover feeding and can produce up to 300bph. There’s a PUR version as well as a Duo model that lets the operator choose between EVA and PUR. 

Morgana makes the Digibook range of perfect binders, which all use PUR glue. The top of the range is the DigiBook 450, which has an automatic cover feeder and can handle up to 450bph, with spine thicknesses ranging from 1 to 50mm. There’s an option for using hotmelt glue. 

Muller Martini has several options for perfect binding soft-cover books, including the Vareo, designed as a flexible and relatively compact solution. It’s a highly automated system that includes barcode matching of cover to book block. It can use both hotmelt and PUR glue and automatically feeds the book blocks. It measures the size and thickness of each book and can handle variations from one book to the next. 

Conclusion

There’s no simple choice with most printers using multiple technologies and choosing the most appropriate for each job. However, Seaber says: “There are no two book printers in the UK that have the same solutions. They are all different in one way or another: they are using different paper, different print technology, or doing different types of books with different deadlines so there are all sorts of variables that need to be considered.”

There seems to be an even split between inline and offline set-ups, depending on the application. Offline generally allows for more flexibility, particularly with multiple presses. Seaber adds: “With uncoated paper where the ink will dry faster they might consider inline but it depends on run length.”

The more expensive systems are highly automated and much more productive. But as Watkiss points out: “There’s always a trade-off. The more automated a machine is the easier and quicker it is but if you haven’t got enough run lengths then you probably don’t want to invest so much money.” That said, several systems offer options such as barcode readers and volume feeders so that they can expand as the business grows.

It’s also worth noting that whichever binding method you use will be just one of several processes that also including collating and folding the sheets as well as trimming the finished book. There may be more flexibility in keeping these processes separate but some systems will include some or all of these processes, which in turn will make a difference to the total amount of investment needed to set up a book production line. 

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