EXPERT ONLINE: Inline Sheeters: What to Look For

More high-volume, sheetfed printers are realizing the benefits of buying paper in rolls and cutting their own sheets. A sheeter that feeds directly into a press supplies only the number of sheets to print, allows the press operator responsibility for sheet quality and results in fewer misfeeds at the press—at a savings of up to 15% in sheeted paper costs. Paper rolls routinely are warehoused three or four high, lowering space and carrying costs for web inventory.

To optimize inline sheeter performance in your plant, watch for these technical design features:

Shaftless self-loading is a popular roll stand design feature that allows for safe roll changes without the need for overhead hoists—within two minutes. When outfitted with tapered chucks, multiple core sizes are permitted, minimizing changeover times when switching to thicker paper grades wound on larger cores.

Web-conditioning systems include accumulators that allow the press to ramp up to maximum speed or come to a controlled stop without affecting the sheeter's cut-off accuracy, yet still maintain a sheet-to-sheet speed from the roll to the press. The accumulator expands its festoon during press slowdown and contracts during acceleration.

Inline slitting, prior to cutting to length, trims oversized rolls to finished widths—allowing the printer to standardize roll widths for inventory purposes and respond quickly to delivery demands. A slitting rig provides flexibility for standard widths, and the draw drum pulls in the web without short sheets.

The high-speed tape section pulls the sheet away from the cutter at a faster rate than the line speed, achieving successful under-lapping. The top tapes can be raised pneumatically to assist in removing end-of-run sheets. To avoid marking, select the belting in the tape system.

At the end of the high-speed tape section, sheet shingling begins. High-speed under-lapping requires control over the lead and the trail edges. Here, air guides are employed similar to those seen on many of today's big presses. As the sheet enters the slow-speed tape section, an Airfoil device uses the Bernoulli Principle to suck up the tail end, permitting the leading edge of the next sheet to pass underneath it. This creates a positive under-lapping at speeds up to 18,000 iph without mechanical touching.

The retractable tape section delivers the sheets to the press—either by passing the press feeder or developing a short pile (as required in a right angle application). The ability to retract the conveyor from the press feeder frame allows skid feeding as required. This section slides out from underneath delivery; motors raise the tape system into position to the press's incline conveyor and feeder assembly.

Retractable sheeter designs allow the flexibility of skid feed or inline sheeting as circumstances demand. When outfitted with automatic splicing and reject gate to divert spliced product, a sheeter can outpace printing press capacity.