Analysis of Common Faults of Offset Transfer Printing Machine (3)

Bad overprint:

Phenomenon: After the color sequence ink overprint or not overprint.

the reason:

<1> After the color sequence ink is more viscous than the preceding sequence ink, the previous color ink is pulled off.
<2> After the color sequence, the ink is pulled off before the ink is too large.

Countermeasures:

<1> Change the color sequence or reduce the viscosity of the color ink after the color sequence.
<2> Reduce the color press of the color printer after adjustment.

Bad drying:

Phenomenon: poor drying of ink, sticky ink on the cooling roller.

the reason:

<1> The surface temperature of the paper reaching the box is not high enough so that a considerable amount of solvent in the ink cannot be removed.
<2> The cooling effect of the web after printing is not good.
<3> The paper used has poor absorbency or the print has too much ink.

Countermeasures:

<1> Increase the paper surface temperature or reduce the print speed.
<2> Reduce the cooling drum temperature.
<3> Reduce the ink supply or use absorbent paper.

· Paper breaks:

Phenomenon: The printed product will crack when folded.

Cause: The oven temperature is too high and the paper is dehydrated.

Countermeasures: Reduce the oven temperature.

· Bad rubbing resistance:

Phenomenon: The print is not resistant to rubbing and discoloration.

the reason:

<1> Low oven temperature thermosetting ink is not completely dry.
<2> The pH of the dampening solution is too low and the print is not drying properly.
<3> Strong Absorptivity of Paper Absorber
<4> There are few anti-friction additives in the ink.

Countermeasures:

<1> Raise the temperature of the oven to thoroughly dry the prints.
<2> Increase the pH of the fountain solution.
<3> Select moderately absorbent paper.
<4> Replace the new ink and add a rubbing aid afterwards.

· Bad gloss:

Phenomenon: The brightness of the printed product is not enough and the gloss is low.

the reason:

<1> The supply tank temperature is too high, resulting in thinning of the binder in the ink and excessive penetration of the paper.
<2> The print is not completely dry.
<3> Insufficient ink or low gloss of the paper itself.

Countermeasures:

<1> Lower the oven temperature and adjust the appropriate paper surface temperature.
<2> Adjust the temperature and printing speed so that the print is completely dry.
<3> Select high-gloss paper to increase the amount of ink in the print.

·Ghosting:

Phenomenon: Two or more identical prints appear on the print.

the reason:

<1> Mechanical ghosting: Loosening of the plate or blanket.
<2> Imprint overprinting is not allowed.

Countermeasures:

<1> Adjust the plate and blanket.
<2> Adjust the rules of the printing press to improve overprint accuracy and exchange overprinting sequence.

· Inequality:

Phenomenon: The print product is uneven or the cross section of the printed product is wavy and uneven.

the reason:

<1> The amount of printing water is too large to deform the printed product.
<2> The paper roll of the printing press has too much force to deform the paper.

Countermeasures:

<1> Reduce the amount of water when printing.
<2> Adjust the tension force of the printer tension roller.