To my knowledge—at least since I've been the Print Production Manager at MORRIS—we haven't used flexo printing.
Recently we were asked to design a ticket that would be printed using this method. The difference between offset printing and flexography is that the image is transferred directly from the plate to the substrate (no blanket), in this case paper. It's used most often for packaging. A flexo press can print on a variety of materials, including plastics, labels, cardboard, etc.
Here are some tips and limitations to consider when designing packaging. This info came from packageprinting.com.
Although many of the recent improvements in flexo printing have broadened its capabilities, specific factors need to be understood when designing graphics for this process. According to Terri McConnell, director of brand strategy for Gravity, a subsidiary of Phototype, flexo has a several important limitations that must be considered. These include:
• Dot gain is a problem, especially when creating drop shadows and soft gradients, blends, and vignettes;
• Minimum line weights and type sizes are more difficult and traps are often heavier, making small type areas and more elegant, fine-line aesthetics challenging;
• Registration limitations dictate the use of outlines around reverse copy and graphics on backgrounds made from more than one color;
• Having to run separate plates for tone/screen and solids of the same color can significantly impact the number of ink stations available for design, notes McConnell.
“There’s no question that designing for flexo requires special consideration and forethought,” observes Rick Murphy, creative director for Gravity. “Just as an artist has to understand the unique characteristics of watercolors versus oils, package designers must understand the differences between the flexo and offset or gravure mediums in order to conceptualize a winning package that won’t disappoint when it comes off the press onto the shelf.”