Setting the precedent

There are many factors that influence which print technique is eventually used in production. For the more commercially minded, a good starting point is to consider the scale of production in terms of order size, to best calculate the most efficient return on investment. At its simplest, the outcome can be decided as follows: above 100,000m2 is usually flexo or gravure, between 5,000–100,000m2 is offset and below 5,000m2 is best handled with a digital run. Keeping in mind that the average customer is also facing increased demand for shorter run lengths, decreased lead times, reduced solvents, quality demands and flexibility in press configuration. Ultimately, offset remains the leading choice for companies with an average order size between 5,000–100,00m2.

Although the consensus is that offset is a complex technology, it is deceptively simple. Some of the key areas it excels in are image carrier, water, inks, web tension, reliability and use of solvents. This makes for a compelling set of reasons to celebrate offset, even as the number of choices increases with the progression of digital.

Image carrier

Offset is a technology which uses thin plates. An image carrier is made in 5 minutes, is inexpensive and requires minimal storage and cleaning costs – as it is much easier to make new plates for every order. Felip Ferrer, offset brand manager at Comexi, is aware of these benefits. As a provider of systems for flexible packaging that use offset, Comexi has had a number of successful launches in the area, including the F1 – which boasts an automatic changeover. It is an innovative solution that incorporates a robot capable of automatically manipulating anilox, plate and intermediate sleeves. Improved ergonomics, a better access for maintenance and a high-performance electronic system enable printers to boost their production capacity by at least 25%, as well as increase the number of jobs managed by 30%.

“Comexi’s offset technology has been awarded with EMAS in Europe and is a world renowned and recognised solution for its commitment to the environment. It has flexibility of production and an ability to adapt to the current demanding time to market. That is why our Comexi CI8 offset printing press has been one of the most demanded machines,” says Ferrer. “A robot has been incorporated into this press, which is fully integrated and able to handle all the sleeves involved in the printing process automatically. It is efficient, reduces downtime of the process and improves the ergonomics.”

Brian Cook, application development manager for MacDermid Graphics Solutions, is also focused on the benefits of good plate management, “LUX lamination is still our most popular product and there are two reasons for this. Firstly, LUX lamination allows our customers to use any plate product in our product line designed for round-top digital exposure to create flat-top dots. LUX lamination also allows customers to choose whether they want to alter the surface of the plate for improved ink transfer with our LUX M200 membrane, or keep the smooth surface of typical uncapped plates with the M100 membrane.” In short, image carrier, which is a crucial part of the printing process, is easy to insert, apply, check and recycle.

 Water

Water, plus additives, is called a ‘fountain’ or ‘damping solution’. The control of fountain solution is critical in offset. Todd Blumsack, vice-president at Business Web-Fed Bobst North America, understands the importance of water in offset with relation to the latest presses, saying “In 2016 we introduced new printing presses for flexible materials, as well as a new HMI. The MW 85F and the MW 125F perfectly meet the market requirements for medium- to wide-web width. The inking and drying systems of both models are designed to print solvent-based inks, as well as water-based inks. Thanks to servo drives for impression setting and high-precision mechanical guides, the MW presses can handle impression adjustment with a resolution of 1µ. This precision – in conjunction with the largest anilox roll diameter in their class and excellent register accuracy – makes the press print superior graphics delivered at all speeds.”

Rinus Hoebeke, sales and marketing of the graphics division at Toray, built on the growth in waterless plates. “We are experiencing a demand for waterless plates from across the printing world, the main reason being waste reduction – a hot topic. As a company, we are always looking to the future and checking out for partners – such as ink manufacturers – to work closely with to provide the printing community better products and easier printing methods. The Imprima line of waterless offset printing plates is a result of these evolutions.

“Within the newspaper sector – particularly in local newspapers – there is still a place for print. For Toray, this is very relevant. Our company strategy is to focus on print as a valuable product. We have a new factory and we are also setting up a new research and development centre.”

Ferrer discussed a new offset invention, involving inks, “Comexi has developed a revolutionary solution that adapts to the demanding time-to-market concept. It is offset printing with a central impression cylinder, which offers reduced costs per print and decreases environmental impact due to the EB offset inks devoid of solvents. When offset printing is used, ink control is automatised. Offset technology uses CIP3 and CIP4 technology for pre-setting ink keys control. Offset technology can also modify the ink volume on each printing unit to adjust colour densities by zones. Simultaneously, offset uses a dampening system and ink and water balance for a correct density in printed areas and the cleanest non-printed areas. Printing offset requires standardisation and stabilised printing parameters to achieve colour consistency and production repeatability.”

Blumsack continues, “We would like to offer a few words relating to the use of UV inks in flexible packaging applications for food. It is a topical issue about a technology that provides many advantages, but suffers from some misconception as to its safety for food packaging applications. This has no reason to be, as the combination of energy-curable inks and control systems delivers full compliance with even the most stringent regulations. The Bobst UVTrack system, for instance, measures the UV dose and tracks the safety of every printed metre of substrate, thus providing continuous safety checks, as opposed to conventional random safety traceability.

Web tension

Web tension needs to be controlled due to high forces on the web. Web length has an influence on the web tension and stretch on the material. An offset press can better cope with its tension and web length. Tension determines how you can print and the modularity of the press.   

Blumsack explains, “Our range covers requirements in all sectors, from labels and flexible, through folding carton and corrugated. The systems have to cover changing widths, as well as multi-step processes, all of which can affect the line or be affected by differing tension. There are trends toward thinner mono-layer films with increasingly high-barrier protection, to fulfil the requirement for material down gauging and to increase the rate of recyclability. This poses a challenge to equipment manufacturers as new materials have different mechanical qualities and perform differently from conventional ones. We are very active on this front, with a view to assisting converters facing process performance challenges. Bobst develops processes for production of high-barrier transparent films, such as AlOx, on our web-coating and metallising machine and also solutions for their conversion and machinability, even during the more complex conversion processes required by some packaging applications.”

Reliability

One overlooked benefit of offset is its incredible durability and reliability. With the money being spent to install the systems, it is vital to reduce changeover or downtime, so that the machines can fulfil their purpose and produce goods to pay off the investment. There will be maintenance costs, for cleaning or parts replacement. However, these are infrequent and seamless on a high-quality offset printer. Testing and proofing time is also long enough to perform efficiently without delaying the run and modern printers also have excellent flexibility and can have additional functions added to the press.

“As a final point, there are no solvents. This means no incinerators, atex regulations and no warehouses for cleaning or storage of image sleeves. All of this promises a reduced fire risk.”

It is so important to evaluate all the options that are out there, not only when it comes to web offset, but any printing technology. Offset can certainly hold its own when evaluated against the others, especially when a customer considers the purpose and volume of the task to be completed.