The selection, installation and adjustment of the squeegee in gravure printing have an important influence on the quality of the printed matter. The following is a discussion of the application of the squeegee in gravure printing and some of the issues involved.
First, the selection of the squeegee and the installation of high-speed gravure printing machines generally use steel squeegees with a high elasticity of import. The thickness is 150-180 μm. I have used Italian-made, Swedish-made, Japanese-made squeegees, which are better than those produced in Japan. Its new blades do not need to be ground and are more durable, while Italian-made, Swedish-made new blades must be worn before they can be used.
When installing the squeegee, note that both sides of the squeegee should be longer than the plate 10~20mm to prevent the ink of the plate from splashing on the roller. The steps and key points are as follows:
1. The distance between the linings and the blade back is about 10mm. The distance between the linings and the blades is 5-7mm. However, it is also possible to increase the distance (ie, installing a soft blade) or reduce the distance (as a hard blade) as appropriate.
2. Place the new blade behind the lining, and tighten the blade back screw into the slot. It should be tightened from the middle of the blade first, then gradually outwards, and the two sides should be tightened in turn. Here is a tip to avoid blade warping: When tightening the screw, it should be completed two or three times, not in one step. Should turn the screw while holding a rag to grip the blade and the lining and pull it to the side, so that the knife will be flatter. A flat blade ensures uniform printing plate ink.
3. Use suitable sharpening tools and sharpening methods.
When the stone is not yet used, if the stone is rough, it is not suitable for grinding a new knife. According to practical experience, it is appropriate to use a No. 1 emery paper sharpener to grind new blades or wear old ones with large defects. If you use a No. 0 gold steel sandpaper to grind a new knife, you can use it, but if you use an old blade with a slightly larger gap, it will be hard to grind. If it is sometimes felt that using a No. 1 emery paper to sharpen the blade, it can be finely ground with No. 0 emery paper. There are two ways to sharpen the knife: First, the sandpaper is folded into a V-shape, but care should be taken to remove several layers of sandpaper so that the blade does not cut through the sandpaper and cause injury. This method is more efficient, easier to control the angle of the blade, but not too safe; the other is to use two hands pull the ends of the sandpaper sharpening, this is very safe, but the angle of the edge is not very good control. Too blunt and sharp blades have a negative impact on print quality.
Secondly, the reasonable adjustment of the pressure, sharpness of the squeegee blade, and the contact position with the plate all have an impact on the printing quality. According to actual needs, rational adjustment of these factors can solve many problems in printing.
1. The factors that affect the pressure of the squeegee are the pressure of the cylinder, the difference between the hard and soft blades, the angle at which the squeegee crosses the plate, etc. The greater the slope, the greater the pressure. Excessive pressure will reduce the transfer rate of the ink, and the wear of the printing plate and the blade will be large. If the pressure is too small, the dirty plate or scraper line may occur.
2. The sharpness of the knife The sharpness of the knife depends on whether the new knife, the angle of the knife when sharpening, the type of sandpaper (oil stone) used, etc. The suitable sharpness of the knife should be to both effectively scrape the ink without producing a knife. Sharp blades are often prone to knife marks and wear plates.
3. The distance between the squeegee and the printing plate The distance between the squeegee and the printing plate can reduce the distance between the plate and the printing plate. However, it can easily cause the dirty plate. On the contrary, it can effectively solve the dirty plate and avoid some tiny line marks. Ink transfer rate.
4. Flatness of the knife The flattening and warping of the knife depends mainly on the method of installation. Of course, it may also be related to the sticking of foreign matter in the holder groove or on the blade or lining. When the flatness of the knife is poor, some watermark marks may appear on the edge of the printing surface, or some intermittent line marks may appear from time to time. Some people think that the ink is rough and the ink fluidity is not good. This phenomenon may occur. In fact, this condition may occur even if the knife is uneven.
5. The movement of the squeegee to the left and right of the squeegee reduces the squeegee line, improves the utilisation rate of the squeegee, and has an important effect on the wear of the plate. If the squeegee does not move properly, you should think of ways to improve it.
When the line marks appear in the printing, the first is to cause an edition injury, and the second is that the scraper is not sharp. However, another reason is that foreign objects stick to the back of the blade. The solution is to move the squeegee up and down so as to get rid of the adhesive. If it cannot be removed, the wiper can only be wiped off.
Another problem is related to the scraper, and many people misunderstood that it is caused by the ink. This refers to the occasional irregularity of dozens of line marks of varying lengths. It looks like the ink is piled up. It is different from the squeegee line. It is not continuous, but it is sometimes absent, or the printing port is suspended. 1/2 or 1/3 parts appear, this is in fact caused by the blade pressure is too small or the blade is not sharp enough.
Several indicators of the above scrapers have both differences and similarities. When solving specific problems, one of them can be used, and sometimes it is necessary to use them comprehensively to solve the problem completely. For example, when some intermittent ink lines appear, it is possible to increase the pressure and solve the problem by sharpening the knife. When a severely punished dirty version occurs, it is necessary to combine several aspects. One is to use sharp blades, and the other is to use sharp blades. To increase the pressure, it is necessary to increase the distance between the blade and the contact surface.
When the blade wear is severe and sandpaper and oilstone cannot be used for grinding, special grinding machines can be used for grinding, which can be reused several times, greatly reducing the cost of the squeegee.
Excerpted from China Packaging Yearbook 1999
First, the selection of the squeegee and the installation of high-speed gravure printing machines generally use steel squeegees with a high elasticity of import. The thickness is 150-180 μm. I have used Italian-made, Swedish-made, Japanese-made squeegees, which are better than those produced in Japan. Its new blades do not need to be ground and are more durable, while Italian-made, Swedish-made new blades must be worn before they can be used.
When installing the squeegee, note that both sides of the squeegee should be longer than the plate 10~20mm to prevent the ink of the plate from splashing on the roller. The steps and key points are as follows:
1. The distance between the linings and the blade back is about 10mm. The distance between the linings and the blades is 5-7mm. However, it is also possible to increase the distance (ie, installing a soft blade) or reduce the distance (as a hard blade) as appropriate.
2. Place the new blade behind the lining, and tighten the blade back screw into the slot. It should be tightened from the middle of the blade first, then gradually outwards, and the two sides should be tightened in turn. Here is a tip to avoid blade warping: When tightening the screw, it should be completed two or three times, not in one step. Should turn the screw while holding a rag to grip the blade and the lining and pull it to the side, so that the knife will be flatter. A flat blade ensures uniform printing plate ink.
3. Use suitable sharpening tools and sharpening methods.
When the stone is not yet used, if the stone is rough, it is not suitable for grinding a new knife. According to practical experience, it is appropriate to use a No. 1 emery paper sharpener to grind new blades or wear old ones with large defects. If you use a No. 0 gold steel sandpaper to grind a new knife, you can use it, but if you use an old blade with a slightly larger gap, it will be hard to grind. If it is sometimes felt that using a No. 1 emery paper to sharpen the blade, it can be finely ground with No. 0 emery paper. There are two ways to sharpen the knife: First, the sandpaper is folded into a V-shape, but care should be taken to remove several layers of sandpaper so that the blade does not cut through the sandpaper and cause injury. This method is more efficient, easier to control the angle of the blade, but not too safe; the other is to use two hands pull the ends of the sandpaper sharpening, this is very safe, but the angle of the edge is not very good control. Too blunt and sharp blades have a negative impact on print quality.
Secondly, the reasonable adjustment of the pressure, sharpness of the squeegee blade, and the contact position with the plate all have an impact on the printing quality. According to actual needs, rational adjustment of these factors can solve many problems in printing.
1. The factors that affect the pressure of the squeegee are the pressure of the cylinder, the difference between the hard and soft blades, the angle at which the squeegee crosses the plate, etc. The greater the slope, the greater the pressure. Excessive pressure will reduce the transfer rate of the ink, and the wear of the printing plate and the blade will be large. If the pressure is too small, the dirty plate or scraper line may occur.
2. The sharpness of the knife The sharpness of the knife depends on whether the new knife, the angle of the knife when sharpening, the type of sandpaper (oil stone) used, etc. The suitable sharpness of the knife should be to both effectively scrape the ink without producing a knife. Sharp blades are often prone to knife marks and wear plates.
3. The distance between the squeegee and the printing plate The distance between the squeegee and the printing plate can reduce the distance between the plate and the printing plate. However, it can easily cause the dirty plate. On the contrary, it can effectively solve the dirty plate and avoid some tiny line marks. Ink transfer rate.
4. Flatness of the knife The flattening and warping of the knife depends mainly on the method of installation. Of course, it may also be related to the sticking of foreign matter in the holder groove or on the blade or lining. When the flatness of the knife is poor, some watermark marks may appear on the edge of the printing surface, or some intermittent line marks may appear from time to time. Some people think that the ink is rough and the ink fluidity is not good. This phenomenon may occur. In fact, this condition may occur even if the knife is uneven.
5. The movement of the squeegee to the left and right of the squeegee reduces the squeegee line, improves the utilisation rate of the squeegee, and has an important effect on the wear of the plate. If the squeegee does not move properly, you should think of ways to improve it.
When the line marks appear in the printing, the first is to cause an edition injury, and the second is that the scraper is not sharp. However, another reason is that foreign objects stick to the back of the blade. The solution is to move the squeegee up and down so as to get rid of the adhesive. If it cannot be removed, the wiper can only be wiped off.
Another problem is related to the scraper, and many people misunderstood that it is caused by the ink. This refers to the occasional irregularity of dozens of line marks of varying lengths. It looks like the ink is piled up. It is different from the squeegee line. It is not continuous, but it is sometimes absent, or the printing port is suspended. 1/2 or 1/3 parts appear, this is in fact caused by the blade pressure is too small or the blade is not sharp enough.
Several indicators of the above scrapers have both differences and similarities. When solving specific problems, one of them can be used, and sometimes it is necessary to use them comprehensively to solve the problem completely. For example, when some intermittent ink lines appear, it is possible to increase the pressure and solve the problem by sharpening the knife. When a severely punished dirty version occurs, it is necessary to combine several aspects. One is to use sharp blades, and the other is to use sharp blades. To increase the pressure, it is necessary to increase the distance between the blade and the contact surface.
When the blade wear is severe and sandpaper and oilstone cannot be used for grinding, special grinding machines can be used for grinding, which can be reused several times, greatly reducing the cost of the squeegee.
Excerpted from China Packaging Yearbook 1999
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