Some methods of troubleshooting ghosting shadows

Imprinting ghosting is one of the common faults in the printing process. Its production will affect the quality of the product, but it will result in the unqualified quality of the batch product and it will not be accepted by the customer. Therefore, only by accurately analyzing the root cause of the failure and accurately and quickly eliminating this failure can we ensure the smooth progress of production.
The so-called ghosting, also known as "double printing" or "double shadow", that is printed on the entire layout or a partial layout or a layout of the double outline of the footprint. From the phenomenon of ghosting, it can be seen that ghosting features vertical and horizontal double shadows. The reasons for this are both unilateral and multi-dimensional. Poor equipment accuracy, there are also improper technical operation, process discomfort, and so on.
First, the cause of the phenomenon of longitudinal ghosting analysis and exclusion methods 1. Ink viscosity caused by ghosting too much When the ink consistency, viscosity is strong, the printed sheet in the imprint process produces a trace of slip phenomenon, it is easy to cause heavy The occurrence of shadow failures, especially the lack of bite force of grippers, is even more pronounced with longitudinal ghosting. In this regard, as long as the proper ink transfer process is turned off, the ink is properly diluted, and the auxiliary agent is used to reduce the viscosity of the ink, which can eliminate the double-image ghosting failure.
2. When the printing plate is not tightened or the "bottom pad" is caused by ghosting, due to the lack of scientific operation knowledge, the fastening screws of the plate are not successively tightened, so that the surface of the printing plate has an elastic difference. The local presence of trace bows, and the back padding of the plate is too soft, or the use of multiple pads or pads to make it critical void, can easily lead to local ghosting. In this regard, it is necessary to close the screwing amount of each screw gradually and successively, by avoiding the operation of the good-fitting plate-laying technology and the pad-plate process technology. The child tightened it. Make the plate can not fully and evenly close to the surface of the roller. On the other hand, the pad used for padding on the back of the plate should be harder and try to avoid local multiple pads or hollowing in order to eliminate ghosting.
3. Ghosting caused by excessive printing pressure.
When the pressure between the blanket cylinder and the impression cylinder is too high, the displacement of the blanket deformation will inevitably increase accordingly, so that the ink cannot be restored to the original state immediately after the ink transfer during the imprinting process, so that the impression is accepted from the plate cylinder again. At that time, a slight difference in position was generated and ghosting was formed. In this regard, as long as the roller pressure is properly reduced and the expansion and contraction coefficient of the blanket is reduced, this failure can be eliminated.
4. Ghosts caused by loose blankets or drums When the blanket is tightly stretched, the force is not uniform, so that the local position is not close to the surface of the drum, there is an empty or drum situation, and the back of the blanket When multiple layers of pad or foreign material are adhered, local ghost impressions can easily be ghosted. In this regard, the rubber blanket should be released for inspection, and the bad impressions should be re-tightened to eliminate the impression of ghosting.
5. Ghosting caused by improperly installed plates or blankets.
When the plate or blanket is not clamped, a slight loosening during the stamping process can easily cause ghosting failures. In this regard, as long as a careful inspection to take appropriate measures, you can eliminate the ghosting shadow failure.
6. Ghosting due to abnormal working of the drum pressurization When the parts related to the roller clutch pressure are not adjusted or due to wear, a certain difference in position occurs at each pressurization, resulting in ghost images with different positions. In this regard, as long as the recalibration and adjustment of the clutch-compression mechanism and the repair of the worn-out parts are performed, the drum-disengagement-pressing work will be accurate, coordinated and uniform, and such failures will be eliminated.
7. Grasp the ghost caused by insufficient paper pressure.
When the roller teeth are worn and deformed due to wear, the force exerted on the printed sheets during the imprinting is insufficient, so that the printed sheets slide out of the teeth in the imprint during the imprinting, and the amount of each slip is not the same. At one time, the ghosting of the fistula area occurred due to the fact that there was no accurate overlap between the blurred blots retained on the blanket and the retransferred ink. In this regard, it is necessary to check the teething of the drum. If unevenness or insufficiency occurs due to deformation, the moment should be adjusted again. If the crepe lines are worn and the edges are not tight, remove the new accessories to ensure that the paper edges do not slip and the ghosting faults can be eliminated.
8. Ghost caused by loosening of roller gear or bearing When the printer has been used for a long time, the maintenance and repair work has been seriously implemented for a long time, resulting in serious wear of the roller gear or bearing, inevitable vibration in the imprinting process, imprinting ghost It will follow. In this regard, after the worn parts should be repaired, the fault can be eliminated.
9. Difficulties caused by the lining discomfort of the roller When the lining diameters of the plate cylinder and the blanket cylinder are too large, the speed difference and friction occur due to the inconsistent line speed at each imprint, which causes the surface of the blanket to be misaligned. Deformation, and easy to move the liner material until wrinkles, blotting ghosting failure also followed. In this regard, the center distance of the drum should be re-measured, and the thickness of the lining should be controlled according to the specifications of the equipment, and the roller line speed should be kept consistent to avoid the occurrence of ghosting and ghosting.
Second, the analysis of horizontal ghosting analysis and elimination methods 1. Bad ghosting caused by poor quality When the paper surface is uneven, starting from the edge of the negative situation, the embossing process of paper elasticity, the paper from the bow Scratches on the surface of the blanket cause ghosting problems. In this regard, it is appropriate to knock the paper on the surface as appropriate, or to knead and knead the uneven paper surface to promote flattening of the paper surface, in order to achieve the effect of eliminating partial paper surface print ghosts.
2. Ghosting caused by poor lining When the lining material inside the lining pad is too large or underfilled, as well as local hollowing out, it may easily cause the occurrence of partial horizontal ghosting. In this regard, the rubber lining should be re-arranged and wrapped. After eliminating the bad conditions, the failure can be eliminated.
3. Ghosting caused by axial cylindricity movement When the roller's thrust bearing wears out, or if the thrust bearing screw is loosened, it will be easy for the roller to slip during the embossing process, leading to imprinted lateral ghosting. In this regard, the degree of wear of thrust bearings should be checked and appropriate measures taken to repair them. If the roller thrust bearing is loose, the nut should be tightened and the screw tightly tightened to prevent loosening. This can be eliminated.
4. Heavy backlash, ghosting caused by loose meshing When the gear wear is severe, it will inevitably produce shaking phenomenon in the imprinting process, so that the previous and next times of the imprinting can not be accurately superimposed, thus resulting in horizontal ghosting. There are even cases where longitudinal ghosting occurs at the same time. In this regard, appropriate repair and adjustment measures should be taken to reduce the backlash of the teeth and reduce the center distance so that the gears can maintain a good meshing state and eliminate ghosting failures.
In short, there are many reasons that cause the ghosting ghosting problem. As long as we are good at observing and analyzing the fault phenomenon in production practice, we can deal with such faults quickly and well to ensure the quality of product printing.