Bobst and Esko have collaborated to produce a new gravure system that the companies say more than halves colour matching time, reduces downtime by 70 per cent and supercharges efficiency.
Called smartGRAVURE, the new tool enables gravure printers to benefit from a fully digitalised workflow. Its creators say it optimally produces exceptional and consistent quality, minimising waste of substrates and inks and maximising efficiency across the print process.
Davide Rossello, manager for research and development process at Bobst, says, “In Bobst Italy, we always manufacture gravure,” he said. “Ink control is the final step on this journey. While this process began in prepress, it has now moved to the end of the printing process.
“We were looking to introduce something new. Gravure is a stable technology with less variables compared to others and is always the reference point whenever comparing print quality results, and our focus is on delivering improvements in productivity, management, and efficiency.”
He adds that the fragmentation of orders, with the varying number of jobs and changeovers, means that gravure printers traditionally face challenges when changing the cylinder for each colour, with the colour adjustment process requiring a lot of time to achieve the highest quality.
He says, “As Bobst did not have a colour matching tool, it was left in the hands of the customer. We decided to look at the setup time and say, ‘Okay, let’s simplify all our customers’ presses, and digitalise this process’.
“When printing in ECG, we knew we needed the optimal technology to check the print register to simplify colour adjustment. We needed first class prepress colour software and faced the challenge of combining that in the machine, to fix the colour in a proper way. This is where Esko enters the game.”
David Naisby, business development director with Esko, says the key technology in developing a solution was its AVT SpectraLab. He explains, “This ISO certified measurement device took many years to refine. and today we are proud to be able to measure both media strip and within the printed image during press start-up and during the printing process.
“This is an enabling technology for any press manufacturer to take advantage of, and Bobst clearly understood how they could turn this into an advantage for their customers to improve productivity, reduce environmental impact and ultimately increase profit.”
The team at Bobst evaluated several technologies and determined that Esko had the full solution to address their technological needs. David says, “Working together, the two companies’ research and development departments developed software that simplifies the operator interaction with the AVT SpectraLab XF and allows live density and colour information to be displayed on the Bobst user interface.
“Testing during 2022 produced particularly good results and we are now able to match the readings from the press to the X-Rite Exact Spectrophotometer to be within one Delta E, the industry accepted tolerances.
“With the trend for shorter run lengths, colour matching and the associated waste and time creates a major bottleneck which leads to unacceptable costs for the converter,” he said. “With smartGRAVURE, we have taken a major step forward with this solution.”
Davide adds, “Essentially, Esko gave us the recipe for how we could digitally fix the colour in the machine. As a result, we now have one hundred per cent control over what is happening in the press with smartGRAVURE. With this new tool, users can address any misregistration, tone value increase differences and colour control, all in line. Delta E tolerances are guaranteed, and it also enables the adjustment of process colours, which we can measure in case of any deviation, effectively closing the loop on colour matching in the press itself.
“In terms of controlling production, this means that repeatability can be assured as everything is digitalised. The machine is now doing the adjustments to bring everything in line with the benchmark. This is a new technology that can be implemented in a gravure press to give output for a customer that is fully controlled from the first metre to the last metre.”
Eliminating bottlenecks
With around 50 per cent of time spent on setup and 50 per cent on production, the development experts at Esko and Bobst analysed the data and determined where the bottlenecks in the gravure print process were.
Davide says, “We recognised that the customer was spending anywhere from 45 minutes to two hours colour matching. Obviously, that is a significant amount of time to lose. Because we are machine manufacturers, we never really looked at the chemical composition of the inks being used in spot colours.
“We have an excellent relationship with Esko and as we needed a partner from the prepress world, an expert in software, and preferably a solution that integrated with the Esko Automation Engine workflow solution to read both composition and colour, it made perfect sense to work together.”
Esko’s David Naisby says, “The dream of all converters is to be able to run a press automatically, without having to adjust colour. With this partnership, we are proud to be able to empower operators to achieve their goal.
“The fundamental part of this process is the accurate measurement of colour, as everything in the workflow depends upon this.
“Secondly, the colour data workflow must be simplified. You cannot have press operators entering complex target density and colour values press-side. To achieve this, the SpectraLab XF is connected to the X-Rite ColorCert product that resides in the Esko S2 cloud solution. Specific job colour target information is sent to the press and sets up the SpectraLab XF automatically with the correct values for each printing unit.”
Measuring at high frequency during high production speeds, Esko’s AVT SpectraLab XF ensures perfect colour matching and consistency to a brand’s specification, assisting in reducing waste by alerting for colour density deviations and assisting operators to get back to needed colour tolerances. With the new colour control abilities from Bobst, this ability is translated into an automated closed loop colour solution.
Davide adds, “Our first test was in 2019, and now we have it finally set up on a machine in our competence centre. In terms of the difference smartGRAVURE makes, it is simply better. It makes automatic adjustments, for the base and colour extenders, to bring the colour to the target density.
“In tests, 94.6 per cent of the extended colour gamut have been achieved using smartGRAVURE, with the lowest still an impressive 89 per cent,” he said. “A range of 89 per cent to 95 per cent is surprisingly high, with only some very specialist colours missing.”
“What until today has taken hours can now be significantly reduced to under 20 minutes, depending on the job and colours involved. To replace the cylinder, from the moment the machine stops, it is now just a few mechanical changes, and we don’t have to wash anything. For a new job, colour adjustment should not be needed so we can change the cylinder much faster and be back up and running on the new job in less than 20 minutes.”
David Naisby adds that in terms of actual savings and benefits, the numbers are as impressive as they are staggering. “The increased efficiency means that idle time is reduced by as much as 70 per cent, with what used to take 90 minutes or so reduced to less than a half an hour.
“This clearly creates additional advantages in terms of the availability of presses and an overall improved productivity.”
He says that to measure colour, gravure operators need to print a test run, which involves starting and stopping several times as they achieve colour matching speed, printing around 300-350 meters each time before testing and repeating until the colour is perfect. He adds, “That is a lot of printed material wasted, both in terms of substrate and ink, as well as energy and time used.
“With smartGRAVURE, this can now all be achieved with one single stop and start, meaning as much as a 60 per cent reduction in materials saved at the changeover.
“Not only does this deliver big benefits in terms of material gains, but it also further prevents wastage by enabling print customers to recognise a problem early in the run rather than when the whole reel is complete.”
Davide says for colour quality, a Pantone validation test returned the first ‘Print totality of colours’ rating to ever be attained by a gravure printer. He says, “This was in one run, on the RS 6003 press in our competence centre, with 2,369 colours, where we achieved a 92.1 per cent rating. “With this new tool, gravure printers can enjoy an end-to-end digitalised process, enabling them to meet and exceed the highest industry standards with ease.”
