Flat-Top Dots
Let’s start by stating what is meant by the term flat-top dot. A flat-top dot on a photopolymer plate is one that accepts the transfer of data from an imaging device to the finished plate at a 1:1 ratio. The 1:1 imaging ratio is measured in the file, post-CDI imaging, and ultimately on the final plate.
Now, let’s dive into the details of what we have identified as the most frequent questions people ask about flat-top dots. We will release one question and answer over the next several weeks.
Part 1. Flat-top dots can deliver better consistency within a job and repeat jobs. How?
The structure of the flat-top dot has a single defined point where the shoulder of the dot meets the printable face of the dot. In contrast, a conventional (non-flat top) digital photopolymer plate has a radius from the shoulder to face resulting from the presence of oxygen during the main exposure process. The presence of oxygen creates a sharpening or rounding effect as the finished dot is actually smaller than the ablated image area. Understanding polymer plates displace rather than compress when impression is applied (from anilox to plate and from plate to substrate/impression roll). Using a non-flat top plate displacement occurs along that rounded radius. This results in more variability of the printed dot size based on impression settings. In the case of FTDs, the more defined transition from plate face to shoulder allows that displacement to transfer down the plate shoulder and to the cushion mounting tape. This results in less variability of the printed dot size due to adjustments to impression.
This improved impression latitude also helps to level or minimize the differences between press operator skill levels, different mounting tapes, and challenges presented by runout and tolerances within components of the print station.
In summary, it is the stability of the flat top dot profile that creates a durable image surface, so your prints look great from the first to last impression.
Check us out next week when we answer, "Flat-top dots use less ink and less substrate and thereby minimize the cost of raw materials. How?"
If you want to learn more about this subject, please feel free to reach out to us by calling 1-800-445-4017, or by e-mail at [email protected].
All Printing Resources has formed our Technical Solutions Group (TSG) to encompass our full range of expertise in all critical areas of the flexo process. This team is made up of industry professionals dedicated to being up-to-date on new technologies along with best practices. They are armed with the latest in diagnostic tools and are experienced in problem-solving that can achieve sustainable results. The TSG has walked in your shoes, and have felt your pain.
Click here to read: Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10.