27 March 2017 Digital Printing Technologies

Finishing adapts to cope with shorter runs

The flatbed platen has been an essential tool for carton printers. Now the demands of shorter production runs are provoking a rethink in how cartons are removed from sheets of print.

Printing is the least of the problems for many looking at the opportunity for short run packaging. Finishing the job, through a platen for cutting and creasing, perhaps blanking to remove the unwanted material, window patching and then gluing and packaging are all activities where for many years the emphasis has been on speed to keep up with presses on long runs. A high speed Bobst carton gluer for example can run at 28,000 blanks an hour.

Its platens are rather more sedate, achieving a throughput of up to 11,000 sheets an hour. Rotary die cutting can run faster, KBA is proposing to add die cutting units inline with its Rapida sheetfed presses at 18,000sph. There are no presses to this specification in the field and such sophistication may have to wait until the Varijet 106 hybrid offset/digital press is ready.

In normal working, foiling and coating can be performed inline. Die cutting cannot. The sheets printed by the 17- and 18-unit Heidelberg Speedmasters that MPS has installed in East Kilbride combining reverse printing and coating units, inline foil application, printing and varnishing in a single pass at up to 18,000sph still need to be processes by a conventional die cutting platen.

And here the action of the platen – basically dropping a very heavy weight on to the cartonboard – has not changed for 60 or more years. There has been plenty of innovation in that time, making it easier to load the die cutting formes, faster to lock these in an accurate position and then automating the registration of sheets being loaded to the platen.

“For years we’ve been launching innovations that improve productivity by streamlining processes or by cutting downtime. We’ve been cascading these through our ranges so that now, quick turnaround features like quicklock or matic, which you would only be on top of the range machines 20 years ago, are commonplace at the entry level,” says Craig Moran, zone business director of Bobst.

Order sizes are down across the industry he says. “Today, order sizes have reduced to a point where packaging makers are really having to make some fundamental changes to the way they operate. Putting on extra shifts or adding another machine that is the same as their last one is no longer the answer because unit costs have to be driven down.

“Carton makers are finding that they have to be more productive than ever and that means having equipment that is faster to set and has more uptime. They also need their people to be more productive.”

Bobst has training courses to help customers get the most from the machinery, especially in adopting good practice for effective short run production by having operators who understand what they are doing.

However, the equipment is still geared towards conventional production. While Bobst has an inkjet corrugated press in its line up and says that it is working on a webfed digital press for carton printing, its finishing technology remains wedded to the principles that have stood it in good stead for a generation.

This is no longer the case at Heidelberg where the Primefire 106 B1 inkjet press has been installed at its pilot customer. The logic that short run printing demands short run finishing is not lost on the company, though nothing has really emerged as yet.

It has close partnerships with Polar and with Masterwork. At Drupa 2016, the former showed a laser cutting system, but limited in format and certainly not up to the task of cutting B1 sheets. Future generations may change that.

Masterwork is the Chinese manufacturer that is supplying Heidelberg’s packaging finishing technology including carton gluers and platens. It also has high speed, high resolution imaging technology developed to spot flaws in cigarette packaging and would find it simple to spot problems in digitally printed sheets if not removed before this point.

However, while there is a B2 platen in the line up of products, it is not the sort of automated set up machine that digital production of packaging is going to need. The B1 machines range from the EasyMatrix models to the Powermatrix high performance machines.

The EasyMatrix, as the entry level machine, is perhaps within the price range of an investment for short run packaging, but lacks some of the sophistication of the more expensive machines which otherwise match Bobst for features and functionality including the rapid makeready ability that is needed.

Heidelberg plans to pair the EasyMatrix with the Diana Easy as an entry level folder gluer. It will be on show at the Zero Defect Packaging day in the Wiesloch factory alongside Interpack on 10 May.

KBA is a more recent entrant into finishing for packaging. Last year it bought Iberica, a division of Cerutti from whom KBA had earlier bought the Flexotechnica press business. The immediate plans are to add KBA’s feeder and delivery units to the cutting and creasing platen.

The Iberica has had its adherents in the UK, though the machines perhaps lacked the finesse of Bobst. Under new ownership that is sure to change. The machines already feature fast changeover for the dies and the stripping tools. However, for the shorter runs and B2 and smaller sheets that are going to be prevalent in digital carton production, KBA points to rotary die cuttings using a dedicated machine.

It demonstrated this at Drupa 2016 on a B1 unit where print units were adapted to hold the cutting plate mounted instead of a printing plate. It is an extension of the Cito and Kocher & Beck systems which have been used for cutting labels and stickers inline with a sheetfed press. Komori has also looked in this direction in the past and announced plans to include embossing, but nothing ever reached the market.

There are a number of options for cutting and creasing on ultra short runs. Xeikon has developed a half-sized platen which handles a sheet in a two-step process. It cuts the cost of the machine and also of the dies, but is limiting in terms of the size of sheets it can cope with.

Laser cutting was a popular option at Drupa with SEI, linked to HP Indigo, LasX, Polar and Petratto offering this technology. The last also had a digitally controlled series of bars to produce the sharp creases that carton buyers are used to.

However, these are all in the early stages of adoption if not still under development. For now Kama reigns supreme in terms of cutting and creasing for short run carton production. It has the ProCut 58 and ProCut 76 for this market. “We saw the opportunity from cartons early on,” says Marcus Trenau, “and started developing machines for the packaging market.”

The German company had been building equipment for commercial printing and still does, though revenues are now split 50:50 says Trenau. “We asked ourselves how could we enter the market which was dominated by Bobst, Masterwork and so on. In commercial printing we were used to working with short runs, so decided to take this experience to the packaging market.”

It has worked, though not immediately. The first machines were announced in 2008 with little impact. Now the Kama is the product of choice for Xerox and HP when specifying a finishing line. “We started to see the breakthrough last year and since Drupa everyone wants to know about short run packaging,” he explains.

“For us size is important. We think that digital is limited to B2. In a larger format offset will prevail because the cost per unit of a box printed litho and cut on a B1 platen will be less. But with digital printing, people seem to forget to take into account the cost of post press, which in terms of a platen means the make ready, handling the sheets and so on. As a result the cost of a digitally printed B1 die cut sheet is twice that of a B2 platen.”

The same reasoning makes Trenau think that direct inkjet will not be suited to carton printing, at least while the cost of ink is high and cartons continue to require high coverage. “For folding cartons electrophotographic is more cost effective

“For short runs, B2 is more efficient. Above say 1,000 sheets, B1 is most effective. We don’t think that laser cutting is suited to delivering a professional finish.”

The Kamas are designed for fast turnaround and to cope with any registration issues that may emerge with digital printing. Cameras are used to identify the image and move the sheet as it enters the cutting and creasing section. The unit will also emboss in the same pass.

For Trenau the solution will be a mixed production area where runs below 1,000 sheets are produced on B2 sheets, either by litho or digitally. This then takes pressure away from the larger platens and allows them to handle the longer runs.

Kama introduced a fast change folder gluer at Drupa and has notched six installations since then. The same philosophy of a two-minute makeready applies. “We have a customer in Italy who demanded that we prove we could do a changeover in less than five minutes rather than the 20 minutes he had been used to on a conventional line,” says Trenau.

That is prohibitive when the run is only a few hundred boxes, which is where Kama is aiming the FlexFold 52. Some of the first companies to produce digitally printed cartons have been using conventional equipment. It is inefficient to lift a job from the high speed line to run a couple of hundred boxes. The culture of the people let alone the technology makes this difficult.

And it is a cultural change among customers that is driving the demand for shorter runs, for top up quantities, for special artwork. In turn converters have to adapt. Finishing needs a digital outlook just as much as printing.

Gareth Ward

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Heidelberg's EasyMatrix is typical of machines that are designed for a crossover market, where commercial printers are coming into packaging or else want to replace a windmill platen or Cylinder with a sheath curing system that is more automated and up to date.

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