Framing, also called picture framing is an unwanted effect, where ink is getting transferred over image-free-areas of the printing plate. Typically outside of the sheet area.
Framing leads to an unwanted transfer of ink particles in image-free areas of the printing plate due to a disturbed printing process. Framing does not interfere with the printed image, as the barely perceptible small ink particles are removed via the substrate. Outside the printing format, however, the ink cannot be removed or transported back into the inking unit via back-trapping, as moisture on the blanket cylinders prevents this. This means that ink, especially on the impression cylinders, builds up over the entire print run. It is often only when changing plates that it becomes apparent that the printing plates, which have just been cleaned, are inked outside the printing format. This happens because many printing presses get into pressure when the plates are extended. The blanket cylinders, which are dry at this point, adopt the ink from the impression cylinder and transfer it to the printing plate. This results in high and incalculable expenditure of time due to additional cleaning. Framing can cause considerable damage to the press over a long period of time. If the problem is not solved, in the worst case the grippers, guide plates, and other sheet guiding elements can become dirty or even fail. Doubling, register issues, and early wear on blankets are all serious early-indicators. Press-downtime and high fixing-costs may follow up.
Suspect 1 – Ink/Fountain-additive incompatible
In most cases, the fountain additive is not working well with the ink in use. Micro-toning due system incompatibilities and disintegrating of the ink happens.
- Check the fountain solution
- Find proper additives for inkset
- Adjust additive concentration accordingly to manufacturers recommendation
- Try a different set of ink
Suspect 2 – excessive Plate-to-Blanket-Cylinder pressure
- Reduce pressure between the plate cylinder and blanket cylinder
- Check and optimize blanket cylinder packing
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