Road to Flexo : making the switch from gravure
In parts of the world, the Rotogravure continues to be the dominant printing process adopted. The main reason is due to the fineness of the print. To the rotogravure, a 175 Lpi (line per inch) print resolution is a common standard, both achievable and stable. However, this is not the case back then for flexography. Flexography was printing at 100~120 LPI resolution. This made a major difference between the two processes as the fineness of the print can be easily identifiable by the naked eye. It is not until recent years, with the introduction of the CTP plate-making process, flat-top dots, and other technologies that leapfrogged the flexographic process. To allow 175 Lpi, even up to 200 Lpi resolution to be possible on the flexography process. In this article, we will be discussing why some industries are adopting flexography better than others? What are the main reasons that are preventing printers and converters to adopt flexography in some regions of the world?
Why is flexo better adopted in the narrow web industry than in the wide web industry?
At the high level, flexography can be grouped into the narrow web category and the wide web category. A narrow web is often defined by a printing width below 400mm, and a wide web with a printing width above 1,000mm. The narrow web is mainly used for printing labels and the wide web is mainly used for printing flexible packaging. The narrow web industry is adopting flexography better than the wide web industry. Why is this the case? Firstly, as the print width increases, it becomes harder to control the printing process. Therefore, there is a greater requirement for the precision, stability, and performance of the equipment. At the same time, the requirement for the anilox, plate sleeve, ink management system is also greater. For instance, the wide web anilox with greater width and greater diameter is much harder to manufacture than the narrow web application. As result, the initial equipment investment is much higher on the wide web than on the narrow web. Secondly, the substrate used by labels is easier to print on in terms of better adhesive capability. On top, many narrow web labels are printed using UV inks. UV inks perform well under higher line screen and are less prone to plate ink blockage. On the other hand, the ink used by wide web flexography is inherently different than the rotogravure. The rotogravure solvent-based ink is less dependent on the surface tension of the substrate. The solvent-based ink has a better adhesive capability. Moreover, the ink volume of the rotogravure is higher. This results in a better print. For the flexography alcohol-based ink, it is affected much more by the surface tension of the substrate and is easier to cause ink blockage on the plate, especially during high line screen. Finally, the industry standardization in the narrow web flexography is more mature than in the wide web flexography. It is not a surprise that different packaging company produces different printed results, impeding the progression of the wide web flexography.
Some of the main obstacles to switching over from the rotogravure over to the flexography include print quality, cost, and market maturity.
As mentioned earlier, the higher resolution of the rotogravure is one of its benefits over flexography. To match the rotogravure print quality, it is not just about raising the line screen on the plate. It is much more than that. If it was that easy, it wouldn’t be one of the obstacles toward the switch. To achieve a higher line screen print it is about the different mechanisms working together in synchronization. This includes the anilox, ink, plate sleeve, and tape.
Anilox is sometimes referred to as the heart of flexography. This makes sense as the anilox is a critical factor to the print quality. Anilox needs to deliver the right amount of ink on a constant basis. As the line screen of the plate increases, the anilox line screen will need to increase as well. This will increase the chance of an ink blockage at the anilox. Therefore, choosing the anilox with the right cell shape, line screen and volume is critical. At the same time, the maintenance of the anilox makes all the difference. To make sure that inks are cleaned out properly after usage and no ink residues are left over.
Ink is another critical part of flexography. To obtain a quality ink that is balanced in its solid content and cost. To be able to control the ink viscosity and temperature.
To have a quality plate sleeve with a tight tolerance where its outer circumference has an equal diameter length.
To have a plate mounting tape that is able to withstand the repetitive impression force.
It is fair to say that overall flexography is a harder process to master than the rotogravure. However, with the right mindset to follow the standards towards the flexography operation. Quality flexography print matching the rotogravure standard is achievable in today’s environment.
Even though the flexography process is a more environmentally friendly process when compared to the rotogravure. At the end of the day, if the cost is not justified, there will be insufficient incentive for the brand owners, printers, and converters to make the switch to flexography. When evaluating the cost, in some regions of the world where flexography is less mature, it is hard to believe that flexography has a cost advantage over rotogravure. The initial quality press investment and the numerous anilox and plate sleeves that one will have to prepare makes flexography seem more expensive. However, if one includes the operational cost into the equation. For instance, the efficiency, stability, job changing time, ink consumption, energy consumption, substrate savings, VOC emission cost, flexography may turn out to be a cheaper process.
To achieve lower cost by going for the cheaper anilox, plate, tape, blades, and plates may lead to a beginning of a vicious cycle. Lower quality equipment can lead to lower print quality, lower efficiency, higher waste, and unsatisfied customer. Therefore, always aim for cost savings as a whole: investment cost + operational cost, and not just by looking at the investment cost of the equipment and accessories.
Market maturity is one of the greatest reasons for preventing flexography from becoming the dominant process in some regions of the world. Market immaturity implies a less structured supply chain. Is quality ink accessible at a reasonable price? Is there qualified plate-making vendors in the area or does the printer needs to process its own plate? When the equipment breaks down, how fast can the printer get the spare parts for replacement? Without a mature supply chain, it would be difficult for the flexography to become widely adopted.
Market immaturity implies less emphasis in the field. As the field attracts less attention, the related market knowledge, information, and education channels will be limited. This leads to less skilled labor in the field. As result, preventing the field from advancing.
This is a chicken and the egg problem. Without a mature market structure, less printers and converters will want to adopt flexography. When less printers and converters are willing to commit to flexography, it is hard for the market to mature.
In conclusion, the current industry trend towards shorter runs and a more environmentally friendly production process indicates that flexography will eventually become the dominant printing process in regions that are still rotogravure dominant. The only question left is how fast would it get there?