Flexographic Plates Troubleshooting: Problems, Causes and Solution – Part 2

by Any flexo | 9 May 2022 | Printing Flaws

This is a continuation to the series of article part 1 on flexo plates troubleshooting.

If you have not read the first article to flexo plates troubleshooting, we link it here:
Flexographic Plates Troubleshooting: Problems, causes and solution – Part 1

Curling

Problem: Plate starts to curl and potentially causes “plate lifting“ issues
Causes: Different shrinkage behaviour of polymer and polyester carrier film on the back of the plate; main exposure too short; plate processing time too long
Solutions: All plate making parameters should be reviewed and optimised

Insufficient plate hardness

Problem: Insufficient plate hardness resulting in reduced print quality, high dot gain and reduced longevity
Causes: Long washout time; Short dry time or low drying temperature; low UVA intensity during main- or post exposure
Solutions: Confirm correct plate making parameters

Insufficient plate hardness problem in flexo printing plate

Dirty Plate Surface

Problem: Dirty plate surface; Remaining slip sheet layer on plate surface
Causes: Polymer residue redepositing onto the plate surface from the processor; dried solvent drops; lint from cleaning towel
Solutions: Solvent saturation; condition of washout processor should be checked (especially the last wiping brushes); use lint-free cleaning towels or soft brushes for cleaning the plate surface

Dirty plate surface problem in flexo printing plate

Insufficient solid ink density

Problem: Low solid ink density on the print sample
Causes: Condition of the ink; condition and specification of the anilox roller; plate and tape hardness combination
Solutions: Confirm and adjust ink viscosity and overall ink condition; confirm condition and specification of anilox roller; consider to use a different plate type and tape; consider to use a surface pattern

Pin holing

Problem: Pin holing; Ink laydown
Causes: Anilox specification; rheology and viscosity of ink; quality of the white printing; preconditioning of the substrate
Solutions: Confirm anilox condition and specification; consider to test different plate and tape combinations; consider to use a surface screening

Pin Holing

Ink Laydown

Dirty printing

Problem: Print result is dirty in some colours and with high dot gain
Causes: Ink condition not ideal, especially the dry speed should be confirmed, wrong anilox specification; missing dots on the plate
Solutions: Confirmation of the condition of the ink; confirm anilox specification

Slurring

Causes: High impression settings; problems in cylinder rolling conditions; different surface speeds of the cylinders
Solutions: Confirm and correct all printing and press parameters

Read next Flexographic plates troubleshooting – Problems, Causes and Solutions Part 3

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