Analysis of common faults of the most popular adhe

2022-08-23
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Analysis of common faults of offset rotary ink (II)

· circular white spots:

phenomenon: there are round cores in the print. 1. The common dot shaped circular ring of single and double tension machines surrounds a small dot of ink

reason:

1 impurities in the ink stick to the plate

2 the paper powder falls off and sticks to the plate

3 dust particles or other substances on the printing machine

countermeasures:

1 wash the version, remove impurities, and replace the new ink without impurities

2 the successive comparison method is used to remove impurities. We know that the pendulum impact tester is aimed at the impact resistance of relevant materials under dynamic load, and the paper that cannot be replaced with paper powder

3 wash the plate to remove impurities

· plate stacking:

phenomenon: ink or ink mixture is accumulated on the printing plate and image blanket, and local ink is shallow or scratchy in the graphic area of the print

reason:

1 the fluidity of the ink after emulsification is poor and the transfer is not good

2 paper powder or paper wool is mixed with ink and piled up on the layout

countermeasures:

1 replace the ink with good water resistance, or add water-resistant additives

2 replace the paper with less paper powder

· the non graphic area of the printing plate is sticky:

phenomenon: ink can be seen in the non graphic area on the print

reason:

1 the ink has poor water resistance. After emulsification, it sticks to the page and is hydrophilic

2 the surface tension of the fountain solution is large, and the non graphic areas of the version are not easy to be stained with ink

3 the ink roller and plate pressure are too high

countermeasures:

1 replace the ink with good water resistance

2 increase IPA content

3 adjust the ink roller and layout pressure

· out of print:

phenomenon: poor inking in the graphic area of the printing version, reduced print concentration or uneven graphics and texts

reason:

1 the printing plate has poor greasiness

2 the paper powder falling off the surface of the paper wears the layout

3 the image and text film of the version is worn off due to excessive printing pressure

4 too much pH solution in the fountain solution causes the printing plate to corrode and the pictures and texts to fall off

countermeasures:

1 replace the new version

2 replace paper with better quality and use ink with lower viscosity

3 adjust the imprint to reduce wear

4 pay attention to the adjustment of fountain solution and add pH solution in a reasonable proportion

· ink sticking on water roller:

phenomenon: there is ink on the water transfer roller of the printing machine

reason:

1 ink emulsification with poor water resistance

2 the pressure between water roller and plate is abnormal

countermeasures:

proper heating treatment can also avoid the phenomenon of "burning" in the processing process.

1 replace the ink with good water resistance

2 adjust the water roll pressure

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