3 common printing fault analysis and solutions! Included tips!
In the process of map printing, problems such as broken lines, lack of color, scratches by hard objects, and inconsistent color stacking of image maps often occur, which greatly affect the quality and production efficiency of map printing. The author has continuously summarized in many years of production practice, explored the causes and solutions of failures in the map printing process, and shared them with peers here.
Disconnection problem
01
Cause analysis
There are two main reasons for the problem of wire breakage during the printing process:
First, the layout is sticky;
second, the original data is missing during plate making or lost during exposure and development.
When there is a problem of wire breakage, first of all, it is necessary to determine whether it is caused by stickiness (paste), you can use a wet cloth to dip a little plate cleaning paste and wrap it on the ink shovel without stopping the machine, wipe the corresponding bucket roller according to the position of the printing plate, the plate cleaning paste on the bucket roller is transmitted to the printing plate through the chrome plating roller and the dampening roller, and the floating dirt on the printing plate can be removed;
If the above method fails to remove the stickiness, it is necessary to consider whether the graphics and text are lost at the broken line during plate making, and you need to stop the machine first with a wet cloth to get the plate cleaning paste, wipe off the dirt on the printing plate, and then wipe it with a clean wet cloth, and then carefully check the broken line on the printing plate, you can clearly find out the cause.
02
Workaround
If it is the cause of sticky layout, you can use a damp cloth to scrub the plate to solve the problem in the process of finding the cause.
If it is the reason for the loss of layout graphics and text, it can be solved in two situations.
First, when there is a broken line problem at the beginning of printing, the plate is usually repaired with a refill pen, but the refill pen is thicker, and if the line is thin at the broken line, this method cannot be used.
Through long-term exploration, the author usually uses the thimble needle method to solve such problems, that is, to connect the needle points into a dotted line to achieve the purpose of filling the gaps.
In the process of needling, it is necessary to ensure that the needle punch line is absolutely consistent with the broken thread, the thickness of the broken thread is expressed by the depth of the needle punch, the fine line is the needle punch shallow, the wire is thick the needle punch is deep, the needle punch point gap should be uniformly controlled at 0.5mm, and the proofs should be compared in real time during the needle punching process, and the ink of the color group should be used to fill the needle punch area after the needle punching is completed.
Second, when the printing production is completed in part or in all of the tasks, the disconnection problem is discovered, and usually all the printed products will be scrapped, corrected or re-plated, and then reprinted.
Workaround
The author's method to solve such problems is to re-plate only the broken wire and the corner line, overprint on the printing sheet with the broken wire problem, and then repair the corner line when the broken line can be accurately overprinted, and only print the broken line.
Color deficiency and color stacking inconsistency
01
Cause analysis
The problem of color loss and color stacking inconsistency mainly refers to the phenomenon of inconsistency with the requirements of the proofs after the superposition of yellow, grade, blue and black colors in the map printing process. There are two main reasons for this:
First, the ink density is inconsistent;
Second, the rubber blanket air cushion is damaged, and the cause can be found according to the following methods.
First, check the ink density. Experienced operators can see the depth of ink with the naked eye, and add or subtract ink in time to make it meet the standard ink color requirements. Inexperienced operators can use a reflection density meter to measure the density of each color, the density is large, the ink color is dark, and the opposite means that the ink color is light, and the ink is added or subtracted according to the actual situation.
Second, check if the blanket air cushion is damaged. If there is a problem, stop the machine in time, touch the rubber blanket with your hand on the place where the ink color is obviously uneven, if you feel that the rubber blanket is dented, it means that the air cushion has been damaged here.
02
Workaround
When there is a problem of color loss and color stacking due to uneven ink density, the operator can make appropriate adjustments to a certain ink area or the entire ink area where the ink color is inconsistent.
When the blanket air cushion is damaged and the color stacking is inconsistent, the operator can use xylene to tighten and expand the blanket air cushion and repair the damage. If the air cushion is seriously damaged, the lining paper in the damaged area can be thickened accordingly to ensure the printing effect.
Redundant graphic problems
01
Cause analysis
There are three main reasons for redundant graphic problems:
One is sticky;
second, the original data is redundant or there are impurities on the exposed lens during plate making;
Third, the layout is scratched by hard objects, and the reason can be found according to the following methods.
After stopping, wash the printing plate with a damp cloth, carefully check the excess graphic parts on the printing plate, if it is due to stickiness, wipe it clean with a damp cloth; If there is excess original data or impurities on the exposed lens during plate making, it can be clearly seen after wiping the layout; If the layout is scratched by a hard object, touching the surface of the plate with your hand will feel prickly.
02
Workaround
If it is due to stickiness, washing the plate with a damp cloth can solve the problem.
If it belongs to the reason of excess graphics and text on the printing plate, and when printing first starts, the plate is usually repaired with a plate repair pen, but the plate repair pen is relatively thick, if the excess graphics and text exist in the middle of the contour line or text, it is difficult to repair it with a plate repair pen.
The author's method of solving such problems is to use toothpicks to stick the plate repair paste for repair, and the wet cloth can be placed under the palm of the hand as a support point to fix the arm to avoid shaking, and quickly wipe it clean with a damp cloth after the repair.
If it is the cause of scratches on the hard object on the layout, the treatment method is to use a clean damp cloth to dip the plate repair paste first, then dip a little wetting powder, gently wipe the scratch on the plate a few times, and then add water to the plate and idle it a few times when starting printing, and then put the ink roller, under normal circumstances, the scratch will disappear. When the scratches are heavy, you also need to use a corrosive stick to gently sand the scratched part of the printing plate, and then wipe it clean with a damp cloth.
When some or all of the printing production tasks are completed, redundant graphic problems are found, if the finished products are treated as waste, it will cause great waste, and manual processing methods can be used to remedy it.
Specifically, the finished product with excess graphic problems is removed from the printing machine, placed for a period of time, and after the ink dries, the excess graphic part is scraped off with a single-sided blade. Pay attention to the light movement when scraping, so as to scrape off the lint on the paper. After scraping treatment, use an eraser to slightly wipe the scraped area.