This is a continuation to the series of flexo plates troubleshooting part 1 and 2.
If you have not read the first article on flexo plates troubleshooting, we link it here :
Flexographic Plates Troubleshooting : Problems, causes and solution – Part 1
Flexographic Plates Troubleshooting : Problems, causes and solution – Part 2
Blocking:
• Problem: Ink transfer from one print to the next.
• Causes: Ink drying problems; web tension issues; substrate humidity problem.
•  Solutions:  Optimization of ink, substrate and dryer parameters.
Ink splashing:
• Problem:: Ink splashing.
• Causes: Ink viscosity too low; wrong anilox specification (volume too high and/or line count too low).
• Solutions: Correct ink viscosity; optimize anilox specification.
Registration issues :
• Problem:: Registration problems in print.
• Causes: Issues during plate mounting; equipment problems during plate making (drying unit); plate orientation on imaging system; separations made from different raw material batches.
• Solutions: Confirm functionality of plate making equipment; image separations in the same orientation on the CDI; use plates for different separations from same raw material box/batch.
Element edges start to print earlier:
• Problem:: Element edges start to print early.
• Causes: Cupping issue; high anilox to plate or plate to substrate impression.
• Solutions: Optimization of plate making parameters (especially dry times); optimization of impression settings on press
“Unsharp“ printing
• Problem:: Unsharp printing result; high dot gain.
• Causes: Excessive plate swelling from unsuitable solvents or cleaners could result in plate softening during printing; high impression settings; possibly „cupping“ issue; possibly ink issue.
• Solutions: Confirmation of suitable solvents; possibly reduce impression settings.
Ink transfer issues
• Problem:: Ink transfer issues.
• Causes: General ink issue; ink drying on the anilox roller; plate surface contaminated.
• Solutions: Confirm the condition of the ink; cleaning of plate surface and anilox roller.
“Filling in“ of fine elements
• Problem:: Fine printed elements start to fill in with ink .
• Causes: High anilox to plate impression; wrong ink viscosity.
• Solutions: Confirm anilox settings; check and correct ink viscosity.
Ink “bleeding“
• Problem : Ink starts to bleed; no defined screen structures visible.
• Causes: Improper pigment use in ink formulation; pH issue in water based ink formulation.
• Solutions: Consult your ink manufacturer.
“Dirty printing“ in transitions of flexo plates
• Problem:: Screen transitions start to print dirty.
• Causes: High anilox to plate impression setting; low ink viscosity; high anilox volume; shallow intermediate depths or plate relief.
• Solutions: Optimization of press and ink parameters. Correction of plate making issues.
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