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FLEXO Magazine : June 2014
The Times, They Are A-Changin’... Again Examining The Anilox Roll’s Many Design Changes Tom Cassano T he 60 degree hexagonal laser engraving has been the mainstay of flexo printing for years. While its attributes and performance advantages over other patterns are known and understood, it is not the “silver bullet” needed to satisfy all flexo printing needs and, most importantly, some of the continued challenges printers experience. The truth is, just as its predecessors have limitations, so too does the 60 degree hex pattern. EARLY CELL DESIGN The earliest laser anilox rolls were engraved with a “random cell”; meaning there was no true pattern to the engraving, just myriad holes burned into the ceramic coating. As seen in Image 1, the holes (cells) are inconsistent in size, shape and depth. This is due in part to the ceramic technology available at the time and laser and software capabilities. This inconsistency and variability made these engravings unpredictable in performance, virtually impossible to reproduce and very difficult to measure volumetrically. As both ceramic quality and laser capability evolved, the next generation of engraving that came to the industry was the 45 degree diamond (Image 2). This was the first true “pattern” created on an anilox roll surface. These engravings were slightly more consistent and a bit more predict- able than random engravings, but repeatability was a challenge. This was due to the fact that a round laser beam was used to create a “square” diamond shape. As such, these too were difficult to measure volumetri- cally using the measurement technology available at the time. FROM ZERO TO 60 Further advancements in ceramics, laser technology and software— and a lot of R&D by a major supplier—yielded the next iteration of patterned engraving: The 60 degree hexagon (Image 3). As the shape of this cell is much more closely related to the round laser beam by which it was formed, it is more consistent in size, shape and depth than its earlier counterparts. Repeatability of this pattern from roll to roll is Image 1 Image 2 Image 3 66 FLEXO | JUNE 2014 TECHNOLOGY & TECHNIQUES Anilox Roll, Doctor Blade, Ink Selection Guide