Offset printing fault handling

XIV. Why is the flower version eliminated?

The flower version refers to the narrowing and emptiness of the dots on the printing plate, the weakening of the sense of fat, the loss of fine ideas, and the dullness of color. The cause of the floral version and its elimination methods are:

(1) The pressure between the plate cylinder and the blanket cylinder is too large and the thickness of the cylinder liner should be reduced;

(2) The pressure between the water roller and the upper water roller is too small (water volume), and the pressure of the water roller and the water roller should be properly adjusted;

(3) The dampening water is too acidic, and it should dilute dampening water to reduce its acidity;

(4) When the amount of water is too large, the amount of water supply should be reduced;

(5) The viscosity of the ink is too high, a certain amount of ink should be added to the ink to reduce the viscosity of the ink;

(6) The printed version is already printed in the process of plate making and printing, and it should be replaced with a new one.

15. What are the reasons for the paste version? How to eliminate?

The reasons for eliminating stencils and eliminating them are:

(1) The pressure between the plate cylinder and the blanket cylinder is too large, and the pressure between the plate cylinder and the blanket cylinder should be reduced;

(2) Relying on the plate roller and plate pressure is too light, the pressure should be readjusted (2.5-3mm);

(3) The pressure on the plate roller and plate should be reduced;

(4) The dampening water is too acidic and the acidity of dampening water should be properly reduced;

(5) Ink is too thin. Add "0#" ink to the ink;

(6) Too much ink should reduce the amount of ink supply;

(7) Add excessive amount of desiccant in the ink, the ink roller should be cleaned to reduce the amount of desiccant in the ink;

(8) Printed body is too fine and should be replaced with a new one.

XVI. Causes of back stains and remedies

Back scumming refers to the fact that the newly printed sheets are stacked together. The ink on the bottom of the sheet is rubbed against the back of one of the sheets, resulting in contamination of the printed sheets.

The reason for removing the back of the back and how to remove it is:

(1) Ink drying is not good or the amount of ink is too large, appropriate amount of desiccant and anti-sticking agent should be added to the ink or reduce the amount of ink;

(2) Stacking the paper too high should reduce the stacking height of the paper;

(3) The ink is not dry and the paper is too heavy;

XVII. Causes of ghosting

Ghosting, commonly known as double printing, ghosting, has two kinds: axial ghosting, in which the footprint of the ghosted part is approximately parallel to the axis of the drum; the circumferential ghosting, that is, the marking of the ghosted part is perpendicular to the axis of the drum.

Causes of axial ghosting:

(1) Poor machine accuracy and bearing wear.

(2) Axial displacement of the plate cylinder or blanket cylinder occurs.

(3) Axial movement of the ink roller (or the plate roller is not compatible with the original machine)

(4) Paper "Ruffle"

The reasons for the weekly ghosting are:

(1) The blanket is not tight

(2) The drum pressure is not in place

(3) The machine is used for many years, the roller gear, bearing wear, or clearance between the three rollers is too large

Source: Guangdong Printing Network