Offset printing and rotary technology have never seemed a perfect match for package printing – where folding cartons are dominated by sheetfed offset and flexible packaging by gravure or CI and inline flexo – but rotary offset is now grabbing a slice of the market, writes Nick Coombes.
With brand owners demanding smaller quantities at shorter notice, package print converters, who know that top quality is expected, are looking for new ways to manufacture and they are wondering what rotary offset can offer.
Long accepted for high quality in commercial print, offset has been slow to make the transition to package printing. But, with lower prepress costs than flexo or gravure, its major competitors, offset is attracting interest from converters needing to improve margins, and press manufacturers concerned that their traditional market sectors are in irreversible decline.
Variable technology makes its mark
Muller Martini uses its offset know-how to provide a genuine alternative to flexo and gravure in the package printing sector. Key to the company’s success is the variable size printing offered by its VSOP and Alprinta V technology. Perfectly suited to shorter run work with frequent job changes, the simpler and cheaper prepress, faster setup times, use of UV- or EB-cured inks and varnishes, and reduced substrate waste, move the company’s rotary offset offering into the area of highly cost-effective production.
According to one of its customers, the Swiss company Nyco, offset offers a lower cost per square metre than either flexo or gravure, and helps to keep prices competitive. The value of this comment is that it comes from a company that operates all three processes side by side, and is therefore in a good position to make comparisons.
With run lengths down by at least half since 2000, the pressure on cost-effective production has never been greater. Take flexible packaging as an example. It has always required different print lengths, which ruled out offset presses until the advent of variable repeat technology.
These days, lightweight plate and blanket sleeves make offset a viable alternative to the established flexo and gravure processes in the production of shrink sleeves, labels, wraparounds, in-moulds, pouches and folding cartons.
Flexibility with precise servo control
The Swiss manufacturer Gallus has also moved into offset. Well known for its narrow web label presses, the company has developed two of its high specification lines for offset printing.
The full servo drive RCS 330 set a new benchmark when it was launched as a flexo press for label production, and its success prompted Gallus to design and produce an offset version, which is now also available in a 430mm web width.
Flexibility is the major benefit of an RCS, with its modular design that allows a wide range of substrates to be handled with the precise control that full servo drive offers.
Gallus claims that the quality of flesh tones used frequently in the health and beauty care markets, and the fine control of vignettes, make the RCS offset line a creative tool that designers can use to maximise on-shelf product appeal.
Lower printing plate cost is another plus point, while the standardisation that offset offers is valued by global brand owners looking for consistency, said Gallus.
Danish manufacturer Nilpeter has used its narrow web expertise to develop the MO-3300 and MO-4 offset presses, also designed around an open platform principle, which similarly allows production flexibility by combining other print and converting processes inline.
The use of offset printing, in a market largely dominated by flexo, is customer driven, according to Nilpeter. Major brand owners view offset as a quality process, and labels or shrink sleeves printed by this process will be the best match for cartons printed on sheetfed offset, according to the company.
Once again, cost is highlighted as a major benefit of rotary offset. The fall in prepress costs means that using a large flexo or gravure press for short-run work makes no sense, according to Nilpeter.
Also, with offset print quality so close to that of gravure, runs of 10,000–20,000 metres become commercially viable, especially as, like Müller Martini, Nilpeter uses sleeve technology for ease of handling and rapid size changes.
Role of wide web experience
A new entrant to the market for package printing presses is Goss International, which has adapted its Sunday Vpak range of variable sleeve offset lines for package printing.
Based on the company’s experience in medium and wide webs, the Vpak lines are available in web widths from 520mm to 1900mm and capable of speeds up to 450 metres/minute.
The technology is based on eliminating the blanket gaps that impose restrictions on conventional offset presses. The company believes that packaging needs the variable print length capability that is central to its Sunday technology, and is convinced the time is right to exploit the opportunities in the international market, where it says web width is crucial.
In particular, it believes that carton printers accustomed to using large format sheetfed presses are unlikely to invest in a web press they consider ‘half size’.
Making the case for CI
So far, the rotary technology I’ve mentioned has all been inline. But one Spanish company, Comexi, has taken a different approach to offset development for package printing, and launched its CI 8 central impression press for short run, high-quality flexible packaging production.
The concept is based on eight offset printing stations located around the CI drum, with the option of having the first and last as flexo heads for special ink or varnish applications.
The CI 8 is specifically aimed at low calliper substrates like PET, PE and BOPP, but can still run an 860mm web at ‘300m and, significantly, generates as little as 30 metres of waste.
Comexi also confirms that offset has quick and easy prepress, is clean to operate, fast to make ready, and offers top print quality. Importantly, in the highly competitive market for flexible packaging, it claims the new CI 8 makes an ideal complement to existing flexo and gravure capacity.
If quality was yesterday’s yardstick, then cost control is today’s. With an F1 racing car, it’s not just speed on the track that counts – pit stops have a key role too. Similarly in printing, it’s not how fast you actually run, it’s how fast you can make ready to run that sets you apart from the competition.
Rotary offset brings a whole new set of parameters to package printing – and it will be interesting to see the takeup of this new technology by existing converters.