The reason for the ghosting failure of offset printing
1. The ink viscosity is too large. When the ink consistency is large and the viscosity is strong, a small amount of slip occurs during the stamping process, which is easy to cause the ghosting failure, especially when the paper teeth are insufficient, the longitudinal ghosting is more obvious. In this regard, as long as the inking process is well controlled, the ink is properly diluted, and some additives are added to reduce the viscosity of the ink, the imprint ghosting can be better eliminated
2. When the printing plate is not tightened or the bottom pad is weak and solid, due to the lack of scientific working space and large operating knowledge, the plate fastening screws are not tightened evenly in turn, resulting in uneven tightness on the surface of the plate Baole cylinder, a small amount of bow shape in some parts, too soft padding on the back of the printing plate, or the critical emptiness caused by more or less padding in some parts, which are easy to cause local ghosting. In this regard, it is necessary to properly control the operation technology of plate mounting and the technology of plate padding, that is, when the printing plate is tightened, the screw in amount of each screw should be gradually and evenly tightened in turn. Do not tighten a screw at once. So that the printing plate can not be fully and evenly attached to the surface of the cylinder. On the other hand, the padding used for padding on the back of the printing plate should be hard and try to avoid local padding or hollowing out, so as to achieve the effect of eliminating ghosting faults
3. The printing pressure is too high
when the pressure between the rubber cylinder and the embossing cylinder is too high, the displacement of the rubber blanket's extrusion deformation is bound to increase, so the ink can't be restored to its original state immediately after the ink transfer during the embossing process. In this way, when the imprint is received from the plate cylinder, a small level difference is generated, forming a double image. This fault can be eliminated as long as the roller pressure is properly reduced and the expansion deformation coefficient of the blanket is reduced
4. The rubber blanket is loose or bulging
when the rubber blanket is tightened, the stress is uneven, so that the local position is not close to the surface of the drum, resulting in void or bulging, and when there are local multi-layer padding or foreign matter adhesion on the back of the rubber blanket, it is easy to make the impression on the local layout double. For this, loosen the rubber blanket for inspection, and re tighten the rubber blanket after cleaning up the defects to eliminate 1. Remove the imprinting and ghosting fault of various automobile parts
5. Analysis of printing plate or blanket packaging film blowing machine's contribution to the food packaging industry is improper.
when the printing plate or blanket is not clamped, micro looseness in the stamping process is also easy to cause ghosting failure. In this regard, as long as careful inspection and corresponding measures are taken, the imprinting and ghosting fault can be eliminated. 6. Abnormal drum closing work
when the drum clutch pressure related parts are not adjusted properly or there is a certain level difference during each closing due to wear, resulting in different imprint positions, causing double images. For this reason, such faults can be eliminated as long as the clutch pressure mechanism is recalibrated and adjusted, and the worn parts are repaired to make the drum clutch pressure work accurately, harmoniously and uniformly
7. Insufficient pressure of the paper nipping teeth
when the roller teeth are worn and deformed, the force of the paper nipping is insufficient during the paper nipping and stamping, resulting in a small amount of slip from the teeth during the stamping, and the amount of slip is different each time. Therefore, during the next printing, the fuzzy imprint retained on the blanket does not accurately overlap with the ink transferred again, resulting in a double image at the mouth. In this regard, check the drum teeth. If the clamping force is uneven or insufficient due to deformation, readjust it. If the paper nip teeth are worn and cannot hold the paper edge tightly, they should be removed and replaced with new accessories to ensure that the paper nip teeth do not slip when holding the paper edge tightly, and the ghosting fault at the mouth can be eliminated
8. The drum gear or bearing is worn and loose
when the printer is used for a long time, and the maintenance and overhaul work is not carefully implemented, it will lead to serious wear of the drum gear or bearing, which will inevitably produce vibration during the stamping process, and the imprint shadow will follow. Therefore, the fault can be eliminated after the worn parts are repaired
9. Roller lining is not suitable this year.
when the diameter difference between the printing plate cylinder and the rubber cylinder is too large, the speed difference and friction will occur due to the inconsistent linear speed during each impression, which will squeeze and deform the surface of the blanket, and easily make the inner lining material move until wrinkled, and the imprint ghosting fault will follow. In this regard, the center distance of the drum shall be re measured, and the lining thickness shall be controlled according to the requirements of the equipment specification, so as to maintain the consistency of the linear speed of the drum and avoid the occurrence of imprinting and ghosting fault