Flexo presses pack brains, brawn
Design improvements in today’s flexo presses may be found in virtually every inch of these machines, but some of the key advances include automatic registration/impression setting and increased capacity and throughput-all aimed at delivering the efficiencies today’s packaging printers seek.
One example of these improvements includes smartGPS, an automatic register and impression feature from Bobst Group under its Fischer & Krecke brand. The technology allows virtually instant job startup, and as Bobst product manager Kurt Flathmann explains, his company first examined and then virtually reinvented the way printers set up today's new presses.
“We looked at the process an operator goes through to set impression, check for even ink transfer across the plate, and doing all this until he eventually brings everything into register, all while wasting press time, substrate and his time,” says Flathmann. “We looked at this and said the optimum scenario would be to back the process up and do it as an off-line process.”
With that, the smartGPS system was born, which uses an RFID chip and register sensor embedded in each printing sleeve, creating what Flathmann likens to a giant USB thumb drive capable of communicating relevant print data to the printing press. Such print data includes actual print diameter, job design and stickyback and printing plate measurements. Once installed on the printing press, each sleeve’s data is then recalled and moved automatically into the exact register and impression setting.
Flathmann points out smartGPS technology is available on newly manufactured presses, but may also be retrofitted on existing Fischer & Krecke gearless presses. But no matter the age of the application, the benefits are quite clear.
“Prior to this, printers could measure plates in a couple spots and get some general idea what the plate consistency was,” says Flathmann. “But it really wasn’t something that you could use to do anything with from a quality control standpoint. With the smartGPS, you can monitor many parameters and check topography as you go. By monitoring this process, you can see how consistent you are and make improvements if need be. But ultimately, it enables you to control the process.”
Like Fischer & Krecke, Lincoln, R.I.-based Windmoeller & Hoelscher produces a suite of automatic impression and register tools marketed under its Easy Family line for Miraflex, Novoflex and Vistaflex presses. Mike Reinhardt, press product manager for W&H, explains that his company’s EasySet S and EasyReg S offerings can correctly set impression and register all 10 colors of a press using only 35 feet of substrate, a key (and sometimes costly) consumable that printers manage as tightly as possible. But as Reinhardt explains, the Easy Family suite goes one step further with EasyColor, an automatic color matching system.
“Once a you set impression, you take a print sample and compare it to a reference sample,” says Reinhardt. “Then, through software in the machine as well as hardware that weighs each ink container, the system will tell you how much ink to add to bring you within color precisely and how much ink is needed to finish the job." He further explains that the system can dial in accurate color within a Delta E of two, a difference that’s not noticeable to the average human eye.
“That used to be a guy who would look, very subjectively, and say, ‘I’m close. Maybe add a little bit of this or that,’” says Reinhardt. “It takes the art out of it and makes it more of a scientific process.”
W&H's 52-inch Primaflex preceeded the Miraflex, and as successful as the Primaflex proved to be, Reinhardt points out the company heard the same feedback several times over: How about 59 inches?
“Printers are always talking about going wider and faster, because they just need to put more product through the machine to increase ROI,” says Reinhardt. “So we developed the Miraflex, which is sort of a hybrid between our high-end Novaflex and our mid-range Primaflex.” Reinhardt explains that the press covers that 59-inch width printers were seeking, along with a 31.5-inch maximum repeat. Available in either 8- or 10-color versions, the base press speed is 1,200 feet per minute but an enhanced model can reach 1,640 feet per minute.
Miraflex presses also use W&H's patented SpaceFrame structure, which uses purely cast iron and positions the two halves of the frame closer together in comparison with earlier press designs to give superior print quality.
"This stiffens up the machine, and the cast iron helps absorb a lot of the vibrations that run through an operating machine," says Reinhardt. "That’s a real advantage for printers looking to run jobs a lot faster with no bounce."
Windmoeller & Hoelscher