Successful screen production requires handling some simple problems. Screen decontamination is a problem that is easy to handle. However, many operators have done a very bad job. As a result, it has caused waste, affected the printing quality, and shortened the life of the stencil.
When there is dirt or dry ink on the printed part of the graphic, the screen should be decontaminated. After the printer is stopped, the screen frame will be lifted. At this time, some operators will use abrasive cloth with solvent. Wiping the lower side of the stencil, the sound can be heard in the entire printing shop, and the stencil is often damaged.
A truly knowledgeable operator rarely scratches the graphic printing surface of the stencil because he knows that the sharpness of the printed graphic requires that all graphic edges maintain a clear emulsion layer graphic interface. Forced rubbing can damage the graphic interface of the emulsion layer, and even wipe off the emulsion layer, leaving only a bare mesh.
When printing high-line color images, the emulsifier film under the wire is only 5-6 μm thick, and the thread diameter of the mesh itself may be only 30 μm, and it cannot withstand friction. Therefore, the key to avoid rough decontamination is to first prevent the stencil from being contaminated.
The main cause of the template pollution is the improper control of the ink, leaving dry ink in the mesh. When using solvent-based inks or water-based inks, the reason is that the ink is thin or thick. The additives should be blended at the specified amount when the ink is transferred. In addition, some pre-adjusted inks are often added to the printing process to keep the ink from changing. In the use of UV-curable inks, efforts should be made to avoid exposure of the screen to ultraviolet light and to avoid sunlight.
Another ink control problem is related to improper control of printing speed. Improper adjustment of the speed of the printer, either automatically or manually, can result in uneven supply, which can quickly dry the ink-receiving cells.
The last reason for the ink to dry out is that the squeegee is misaligned or has been worn out. When printing fine images with high screens, a sharp squeegee with sharp edges is required. The horizontal line angle is approximately 75 degrees. Because the squeegee will deform or be worn during normal use, the image clarity of the surrounding area will decrease, indicating that the ink may not be able to pass through the mesh properly. If the problem is not solved in time, the ink will Dry in the mesh. To avoid this, the squeegee should be turned over regularly to extend the life of its squeegee, or it can be replaced with a new squeegee before the print quality has dropped.
In order for the mesh to function properly, care should also be taken to remove dirt from the ink or the substrate. Due to the electrostatic adsorption of airborne contaminants and poor storage conditions, the surface of the substrate will become contaminated with dirt. The above problems can be solved by improving the storage conditions and process control. In addition, the use of static eliminators and substrate decontamination devices can also be used. Prevent dirt and dirt from transferring from the surface of the substrate into the mesh.
What should I do if the template is contaminated? When using a flatbed screen printer, stop the printer after printing a set of prints, and then input a blotter paper so that the screen contacts the blotter.
Let the screen be in the printing position, and then use a non-abrasive soft cloth moistened with a screen cleaner to wipe away dirt from the surface of the squeegee. Do not use excessive force so that dirt can fall through the mesh. The following absorbent paper, if necessary, can be repeated with a piece of absorbent paper to clean the mesh. Some of the dirt particles that fall on the top may be large and cannot pass through the mesh, but they can stick together with a soft cloth. After the cleaning is completed, the stencil can be dried with a blower (adjusted to "cold air").
When cleaning circular press screen printing machines, you will encounter different situations. Due to the design of the structure, it is not possible to wash the dirt on the absorbent paper like a conventional screen printer. Fortunately, because the printing speed is faster, the ink is less likely to dry on the mesh. If this happens, first stop the printer when a group of jobs is printed, and then use a non-abrasive cloth to apply the screen cleaner or thinner to the top of the template at the printed graphic site. Do not leave too much detergent on top of the template. The purpose at this time is to scrub the dirt in the mesh with a solvent.
Sometimes the dirt under the template is also removed. In this case, the dirt should be wiped gently with a soft cloth, and do not use force.
In the production process, the above cleaning and decontamination methods should be used frequently to extend the service life of the template and reduce the scrap rate.
Source: China Screen Printing Network
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