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Short-run saddlestitching: Bridging the gap

Aug 1, 2004 12:00 AM

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Printers with sheetfed presses long have produced saddlestitched booklets using the traditional method of printing multiple-up, perfo- rating and signature folding offline, then loading the eight-, 16- or 32-page signatures into a saddlebinder for gathering, stitching and three-side trimming. Saddlebinding lines can be cumbersome to set up and changeover, and a certain amount of spoilage is inherent, but that's tolerable for longer runs when you can write off setup times and overrun costs of more than tens of thousands of units.

But run lengths are in free fall as customers look to print fewer units to avoid the high costs of inventory, storage and obsolescence. This forces printers to wrestle with the challenge of making a profit on quick-turnaround saddlestitching jobs from 5,000 to 50,000 units. Fortunately, there are new flexible and affordable methods that can help printers stay competitive on shorter runs while maintaining booklet quality.

Alternatives for shorter runs

One widely adopted alternative is to impose the job multiple-up as four-page flat signatures for printing on a small-format press (for example, 23 × 29-inch presses are becoming popular in part due to their ability to impose 11 × 17-inch three-ups). The sheets are cut into four-page flat-sheet signatures, then loaded into a high-speed vacuum collator equipped with inline stitching, knife folding and face-trimming accessories. If the bookletmaking system is automated, it'll provide fast setups and quick turnaround, two ingredients that help bolster finishing profits.

These conventional flat-sheet collating and bookletmaking systems provide production and efficiency advantages, but the method also has its limitations: Maximum sheet count is about 22 (55-lb. offset), because knife folders are ineffective on thicker sets. Booklets may have a more rounded fold than saddlebound products, especially as the sheet count increases. Flat-sheet systems ordinarily are equipped with a face trim only, so proper head and foot trimming is essential. Two-up production is impossible without center chip-out. And finally, typical flat-sheet systems cycle in the range of 3,000 to 4,000 per hour, depending on format and operating conditions that, while fast, limit throughput and turnaround on longer runs.

Hybrid options

To avoid these tradeoffs, a new hybrid method bridges the gap and retains some of the best advantages of saddlestitching and flat-sheet bookletmaking. The Standard Horizon StitchLiner 5500, manufactured by a Japanese bindery equipment manufacturer, combines productivity (up to 11,000 two-up booklets per hour), fast automated setups (less than two minutes to change over the complete system), and the ability to stitch, fold and three-knife trim a 200-page, 50-sheet booklet. One of the new generations of intelligently interfaced Horizon i2i systems, the StitchLiner 5500 features automated setups via a user-friendly touchscreen control panel and the ability to receive JDF job-control data. The construction is robust for heavy-duty operation (the three-knife trimmer alone weighs more than 2,500 pounds), and finished booklets are comparable with booklets completed via traditional saddlestitching machines.

System control

The line is set up and controlled via the interactive icon-based touchscreen on the SPF-30 saddlestitching machine. From the input job information, the control computer calculates and sets the positions of the:

  • Front and back stops and joggers on the ACF-30
  • Incoming set stopper, stitching position stopper and jogger, drive finger position, stitcher heads, clincher and stitch stroke (wire length)
  • Stopper for advancing books
  • Gap of the steel spine-pressing rollers within the SPF-30
  • Top and bottom guides at the infeed section of the HTS-30
  • Back stop for the fore-edge knife, the top and bottom trim knives and the delivery belt speed of the HTS-30.

This entire process is completed within two minutes. The SpeedVAC collator sets itself automatically on the passage of the first “proof” set. The operator may need to adjust the blower, scoring pressure and guide bar in the ACF-30, as well as the gap in the belt guides at the HTS-30 infeed, according to the stock type and job. The touchscreen also is used to fine-tune on the fly. Fitting of the center gutter knife in the HTS-30 — required for two-up production — takes less than five minutes.

The production method

Four-page sections of untrimmed sheets are fed (portrait) from the SpeedVAC and collated in a subset of up to the equivalent of 20 sheets of 80- gsm paper (depending on stock type and required spine definition). At the ACF-30, the subset is jogged, registered and transported at a right angle (landscape) — without turning — through a set of scoring rollers. Then it is plow-folded, dropped onto a saddle and held until any remaining subsets have been delivered on top. When the last subset arrives, the saddle conveys the completed book block to the stitching area for jogging and stitching. Faulty blocks pass unstitched into a reject tray.

After stitching, the booklet is conveyed through a set of steel spine-pressing rollers to the HTS-30 three-knife trimmer (maximum book thickness of 10 mm), where it stops for face trimming, then advances to the head- and foot-trimming station. If required, for example with stock pre-cut to size, the user may select “fore-edge trimming only” or “no trim” on the control screen during setup.

Trimmer waste can be handled with a central evacuation system or via the extractor into a waste container. An optional set of center knives may be fitted for two-up production (book thickness of 3 mm; 6 mm standard gutter). Finished books are delivered onto an electric delivery conveyor with an integrated batch counter.

The StitchLiner system helps tackle some unlikely jobs. Colonial Printing (Cranston, RI) printed a diecut brochure on 12-pt. cover that needed to be scored, folded and bleed trimmed very precisely, so the diecut cover opening lined up perfectly with an inside image. In the past, Colonial would trim the sheets, score and fold them, then send the job to the cutter for final trimming. On the StitchLiner it became possible to set up the crease-fold station, disengage the stitch heads and perform the final three-knife trimming in one inline pass. At least three separate machine setups now are completed on a single, fully automated system.

Finishing digital prints

For digital-print applications, StitchLiner also can be equipped with the Horizon HOF high-speed sheet feeder. It handles a 10-inch stack of digitally collated output, from high-speed cut-sheet or continuous-feed laser printers, and feeds at a rate of 27,000 sph, with optional barcode-integrity checking for personalized booklet production.

As run lengths decline, printers must evaluate new production methods that may better meet their customer's needs. Flat-sheet collating and saddlestitching — using some of the techniques described above — is a proven approach that brings short-run efficiency and profits to the bindery.

Mark Hunt is director of marketing at Standard Finishing Systems (Andover, MA). Standard distributes Horizon print-finishing equipment and a range of print-on-demand feeding and finishing solutions through independent dealers in the U.S. and Canada. For more information, visit