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Consider the steps to produce a folding carton in a typical sheetfed-production system. First, rolls have to be sheeted, then jogged, printed, jogged again, die-cut, and finally sometimes hand-stripped. Only then are they finished cartons, ready for the gluer.

Now, think about a typical web-fed, cartonmaking process. A roll of board is put on one end of the press and finished blanks come off the other end.

Intuitively, most people, even those with no printing or converting background, would be able to spot the more productive process. In our analyses, we have discovered disparities in revenue per labor hour of up to 400 percent when comparing the same work through both processes. Quite simply, fewer workers can produce the same amount (or greater) of work. This is the essence of productivity.

Much is made of the productivity of the 40-in. sheetfed press, with some machines rated at up to 15,000 sph. But, because printing is only one part of making a carton, these super-producers are still hamstrung by the diecutting operation. A 15,000-sph press doesn't do one much good if the diecutter chews through only 6,500 sph. Multiple diecutters can keep up with the faster presses, but these necessities put a damper on true productivity by adding labor and depreciation costs.

Looking now at the flexo side, the productivity of a 26-in.-wide press with in-line rotary diecutting stacks up very favorably against the popular 40-in. sheetfed with flatbed diecutter. A quick calculation shows only 50,555 sq ft of output (6,500-sph sheetfed) vs. 78,000 sq ft (600-fpm web flexo).

This represents gross theoretical throughput; these figures have to be modified to allow for makereadies, starts/stops and all the normal things that can happen on the production floor. However, it exposes an important point–that even a fairly small, web-flexo press has the capacity to outproduce the venerable 40-in. sheetfed machine by a wide margin. One could argue about the speed assumptions, but experienced cartonmakers will recognize the figures as reasonable estimates.

Flexo's second major economic benefit comes from the nature of in-line rotary diecutting. Some might say that this is the primary benefit because paper-waste reductions are sometimes quite dramatic and fall immediately to the bottom line. In any case, with paperboard being the largest single cost component in cartonmaking, it behooves converters to squeeze out every percentage point they can.

By comparing an efficient, sheetfed layout of a reverse-tuck carton with a web-flexo layout, there is no gripper waste using web-fed (which presumes printing-plate sleeves or cylinders made to the exact repeat) and there is also, and perhaps more significantly, no nesting waste. The continuously repeating pattern made possible by the rotary die allows for the most efficient substrate use. The finite surface of the flatbed die places severe limitations on this ability to use paper efficiently. We have found in our analyses that these factors combined nearly always outweigh the much higher cost of the rotary die.

Recent studies support the paper savings made possible by in-line processes. Depending on the mix of carton sizes and shapes one produces, paper savings amount to between 5 to 15 percent. This is chiefly due to the differences in layout mentioned above.

We can examine the positive effects that a 10-percent, across-the-board, paper-waste reduction makes on profit. Simply perform following mental calculation: Paper cost=70 percent of overall cost, so a 10% reduction is 7 percent of overall cost. For every $100,000 of overall production cost, $7,000 can go directly to the bottom line.

How many converters couldn't benefit from a 7-percent cost reduction? And remember, this is just the paper. The productivity advantages discussed earlier, when added to paper savings, make for a truly compelling business case.

In fairness, there are cost components of the web-flexo process that are higher than corresponding costs in sheetfed offset. The most obvious are rotary dies; photopolymer flexo plates cost more than aluminum offset plates, and flexo inks (especially UV-flexo) can run 10 to 15 percent higher than offset. Any comparison should consider all production costs before presuming an advantage for either process.

In today's folding-carton market, having the ability to produce cartons with either process gives converters the flexibility to deal with most anything that comes their way, maintaining market share, reducing costs and maximizing profitability as they go.