On a roll
Nearly every wide-format printer has a dedicated roll-fed unit making them the bread-and-butter machines of the industry. With the huge range of inks and technical specifications now available, Sophie Matthews-Paul says it's easy to see why.
Since the earliest days of wide-format inkjet production, roll-fed printers through necessity have played a cogent role in all types of production where flexible media is used. This was aided by the fact that sign-makers and display producers were mostly well accustomed to working with reels of materials from having used vinyl cutters which, for many, provided an entr?e into computerised production. In the past decade, roll-fed printers have evolved from fairly basic systems to highly sophisticated machines and today's options can handle a variety of substrate weights and sizes to suit a broad range of applications and can, where apt, also output at extremely high speeds.
Wide-format digital print tends to follow trends and fashions. So, when UV-curable inks first came to market, there was an apparent rush from the industry in general to adopt the ability to output direct to rigid substrates as these formulations were the first to be able to do so with a modicum of success. Today we are now spoilt for choice, with roll-fed printers offering every ink technology suitable for virtually all requirements, and developments have progressed briskly across all formulations. Pundits who were pretty insistent that aqueous-based products would die have been proved wrong, and the widespread feeling that solvents would quickly be superseded with UV-curable alternatives has not been realised. Thus all three in their separate guises continue to be strong contenders for wide-format, complemented by a growing band of textile printing options using acid, reactive and disperse dyes.
The quality of print isn't the only improvement that has manifested itself radically since the early developments of wide-format inkjet. Materials handling has also seen steady changes to promote ease of use and better consistency of alignment, plus correct registration parameters for double-sided applications. Speed of throughput depends on more than the mere rate at which the carriage can travel; printhead technology and controls generally have been refined to minimise the chances of banding and poor results.
Although UV-curable roll-fed printers are commonplace today, these have largely resulted from a metamorphosis from their flatbed counterparts. Despite the claim that they can print to virtually all substrates, poor adhesion has presented a challenge on some materials which is often more evident with flexible media where cracking and flaking can sometimes happen. As a result, developments in inks and curing continue relentlessly as manufacturers strive to guarantee reliable results.
The latest arrivals on the roll-fed scene have encompassed all ink types, with new options and improvements available across all technologies. Far from retiring into a has-been production method, aqueous-based machines have continued to play an important role in the wide-format market, as evidenced by Canon, Epson and HP - all of which have added higher quality and faster speeds to their modestly priced portfolios of products. Extra colours provide a wider gamut and better accuracy for high quality work and these additions appeal to the colour-conscious for whom there can be no second-best.
Solvent printers, too, have continued to be developed and brought to market despite continued mumblings about their hazardous chemistries. In combination print-and-cut machines, where Roland maintained dominance for several years, Mimaki has now decided to bring to market its own version. Both of these printer manufacturers have incorporated solvent-based inks with options for additional white, but it's still up the individual user regarding preference for single printing and cutting units or for a combination machine.
Since the three-year agreement with HP came to its conclusion, new introductions from Seiko I Infotech made their way to market at the end of last year, via UK distributor Colourgen, enhanced in the spring with a modestly priced mild-solvent printer. Epson, too, has produced its own low solvent-based machine using an ink formulation which is odourless and can, in principle, be used in many environments without ventilation and fume extraction. Additions such as these up the ante in quality terms and bring the benefits of additional durability.
Currently there's only one challenger which bridges the gap between aqueous-and solvent-based chemistries and that, of course, is HP with its own latex printing technologies. Since the launch of the Designjet L65500 at Drupa 2008, interest and orders have been encouraging and much of this equates to the desire to be able to print more durable results without environmental compromise.
Certainly Mimaki, Mutoh and Roland have continued to introduce products using solvent-based chemistries but this hasn't stopped them from pursuing the UV-curable end of the market, with all three now having their own solutions for working with flexible materials. There are other manufacturers, many of whom have used engines from these three contenders, and we continue to see printers from the Far East being introduced at international trade exhibitions.
Roland's entrant into the UV-curable roll-fed market followed a different path to the majority with its VersaUV offering glossy, even tactile, results and good adhesion. This philosophy has been adopted by other manufacturers using their own inks, with the realisation that flexibility in the formulation would remove many of the former problems associated with roll-fed principles on some media. Developments have also been ongoing with refined types of UV curing now growing in popularity, and LED options are increasingly being introduced into newer models, such as the Mimaki UVJ-160. The idea here is to enable more delicate materials to be used and to broaden the options available to users wanting to move to UV-curable ink technologies.
Roll-fed machines have always played a major role in high production environments, too. Manufacturers at the upper end, such as HP Scitex and EFI Vutek had their foundations based mainly on solvent-based machines but have successfully made the transition to UV-curable inks. From HP's point-of-view, the acquisition of NUR meant that the company had an instant solution which had already proved itself using this chemistry, whilst Durst and WP Digital missed out on solvent chemistries entirely and devoted themselves to developments using UV-curable formulations.
Today's market sees a wide-format roll-fed printer for every type of user, starting from aqueous-based units, through a range of products using solvent families of inks, to those designed to benefit from UV-curable output. Although printing direct to rigid substrates continues to be a major line of investment for many businesses, the ability to use this latter chemistry on flexible media is growing in popularity as users demand fast, unattended production.
Roll-fed printers have proved to be the bread-and-butter machines for print service providers and display producers across all sizes of company. The continued development and improvements in inks and associated technologies have resulted in strong families of reliable equipment designed for all types of use, from occasional prints through to non-stop industrial production.