Pressure is one of the important conditions for the offset and embossing processes. Appropriate printing pressure is also an effective process technology that guarantees normal production and improves product printing quality. However, if the technical measures are not in place and the printing pressure is unsatisfactory, some printing failures may occur and care must be taken.
First, the printing pressure is too heavy due to overprinting faults are not allowed When the roller teether surface wear, deformation, uneven teeth pressure, lack of conditions, the printed sheet into the teeth after the imprint is likely to produce slip phenomenon, resulting in product overprinting is not allowed . Especially in the case of large ink-receiving area of ​​the printing plate, and the viscosity of the ink used in the printing is large, the performance of the product inaccurate in printing is more prominent. The main reason is that the printing pressure is obviously heavy, and after reducing the printing pressure, the ink and the printing effect are not satisfactory. In this regard, the solution is: to replace the teeth with severe new teeth wear; will deform, uneven pressure on the bite paper, insufficient teeth bite, to adjust the entire tooth surface bite the edge of the paper; the viscosity of the ink Too large, moderately diluted with additives to reduce the viscosity of the ink; for printing spot color inks, the ink hue can be appropriately deepened to make the printing ink layer thinner, which can reduce the viscosity of the ink and achieve compliance Printing hue requirements. In addition, the printing pressure is appropriately reduced, and the printing pressure is adjusted so that the ink layer on the printing plate is evenly transferred to the printed sheet. However, the uniformity of the thickness of the underlay is the basis and a prerequisite. These operating techniques have been turned off, so that the problem of overprinting caused by biting teeth is not tight, and this will be easily solved.
Second, the print pressure is not caused by the traces of ink marks When the roller bearing wear serious conditions exist, due to excessive roller yield, resulting in the roller surface sliding friction caused by ink marks, this is a situation. In another case, due to the use of a hard lining, the ink bars are caused by the sliding phenomenon during the imprinting process. The third situation is that the backlash of the roller gear is too large, so that after the roller is pressed, the gears vibrate and the sliding friction occurs on the drum surface to introduce the ink stick. The fourth situation is that the pressure between the plate cylinder and the blanket cylinder is too large, so that the blanket is squeezed to form a large frictional slippage, which causes the longitudinal deformation of the screen surface to expand and cause the ink mark. The above situation should be achieved by replacing the roller bushing; adjusting the characteristics of the packing material; reducing the center distance of the roller, so that the meshing backlash of the gear is less than 0.1mm. According to the specifications of the equipment, the thickness of the packing shall be set to avoid the production of excessive pressure. To prevent the phenomenon of ink sticks.
Third, the ghost pressure caused by printing pressure does not cause discomfort When the pressure between the blanket cylinder and the impression cylinder is too large, the displacement of the blanket deformation deformation correspondingly increases, so the imprinting process can not be restored in time after the ink layer transfer In the original state, when receiving a print from a plate cylinder, a slight difference in position is easily generated and a ghost print is formed. In this regard, it is necessary to reduce the pressure of the roller and reduce the expansion and contraction coefficient of the blanket during imprinting to prevent ghosting failure from occurring. In addition, for the use of aging blankets, should be replaced with a new blanket for printing, to eliminate print ghosting failure.
The printing pressure of the lithography process does not cause ghosting failures, and the embossing process does. When the embossing process employs a multi-layered glued board as a printed bottom mat for printing a large area of ​​a plate product, due to unevenness of the bottom mat and poor solidity, the printing plate vibrates during printing to cause ghosting failure. In this regard, the elimination of measures is that the bottom pad should be flat, the bottom plate should be planed into four sides straight edge, right angle state, so that the plate is firmly attached to the bottom plate after the close, to eliminate the plate "hanging" caused by ghosting failure .
Fourth, the dirty pressure caused by excessive printing pressure and paste plate When the printing pressure is too large, the friction surface of the blanket surface on the printing plate must be increased, so that the plateau sand subject to wear and damage, the blank area of ​​hydrophilicity mutates, The ink is attached and transferred to the print, which is a dirty version. In addition, the printing pressure is too large, the elastic deformation value of the rubber under pressure is also large, the transfer of the imprint is also easy to produce deformation, especially the printing of dots and small text, there are often paste problems. This is even more evident if it is a relief process. Therefore, in order to prevent the occurrence of dirty and paste, it is necessary to accurately adjust the printing pressure. According to the equipment specification, the thickness of the liner and the center distance of the drum should be controlled.
5. Ink coloration caused by uncomfortable printing pressure When the unevenness or insufficient pressure of the unevenness of the liner, when printing, between the printing plate and the rubber, between the blanket cylinder and the impression cylinder, or between the plate and the blanket (the relief process) The phenomenon of poor contact will affect the uniform and full transfer of the ink layer on the layout, which will cause the ink of the layout with insufficient pressure to be light and fade. In order to avoid this unfavorable situation, it is necessary to turn off the printing technology of “Sanping†printing, and the printing plate and the ink roller should be leveled, and the bottom pad of the printing plate should be leveled; the plate and the blanket cylinder or the lining (embossing) should be flat. , should be flattened blanket or lining; imprinting roller and rubber roller should be flat, should protect the surface of the impression roller to prevent loss of deformation and flatness, to maintain uniform and adequate printing pressure, is to eliminate the printing ink ink Effective measures.
In a word, printing pressure is the basis of product quality. Only by carefully concentrating good printing operation technology, scientifically and rationally adjusting, and handling various factors affecting the pressure, can we ensure the printing quality of the product. (Kang Qilai) ("China Packaging News")
First, the printing pressure is too heavy due to overprinting faults are not allowed When the roller teether surface wear, deformation, uneven teeth pressure, lack of conditions, the printed sheet into the teeth after the imprint is likely to produce slip phenomenon, resulting in product overprinting is not allowed . Especially in the case of large ink-receiving area of ​​the printing plate, and the viscosity of the ink used in the printing is large, the performance of the product inaccurate in printing is more prominent. The main reason is that the printing pressure is obviously heavy, and after reducing the printing pressure, the ink and the printing effect are not satisfactory. In this regard, the solution is: to replace the teeth with severe new teeth wear; will deform, uneven pressure on the bite paper, insufficient teeth bite, to adjust the entire tooth surface bite the edge of the paper; the viscosity of the ink Too large, moderately diluted with additives to reduce the viscosity of the ink; for printing spot color inks, the ink hue can be appropriately deepened to make the printing ink layer thinner, which can reduce the viscosity of the ink and achieve compliance Printing hue requirements. In addition, the printing pressure is appropriately reduced, and the printing pressure is adjusted so that the ink layer on the printing plate is evenly transferred to the printed sheet. However, the uniformity of the thickness of the underlay is the basis and a prerequisite. These operating techniques have been turned off, so that the problem of overprinting caused by biting teeth is not tight, and this will be easily solved.
Second, the print pressure is not caused by the traces of ink marks When the roller bearing wear serious conditions exist, due to excessive roller yield, resulting in the roller surface sliding friction caused by ink marks, this is a situation. In another case, due to the use of a hard lining, the ink bars are caused by the sliding phenomenon during the imprinting process. The third situation is that the backlash of the roller gear is too large, so that after the roller is pressed, the gears vibrate and the sliding friction occurs on the drum surface to introduce the ink stick. The fourth situation is that the pressure between the plate cylinder and the blanket cylinder is too large, so that the blanket is squeezed to form a large frictional slippage, which causes the longitudinal deformation of the screen surface to expand and cause the ink mark. The above situation should be achieved by replacing the roller bushing; adjusting the characteristics of the packing material; reducing the center distance of the roller, so that the meshing backlash of the gear is less than 0.1mm. According to the specifications of the equipment, the thickness of the packing shall be set to avoid the production of excessive pressure. To prevent the phenomenon of ink sticks.
Third, the ghost pressure caused by printing pressure does not cause discomfort When the pressure between the blanket cylinder and the impression cylinder is too large, the displacement of the blanket deformation deformation correspondingly increases, so the imprinting process can not be restored in time after the ink layer transfer In the original state, when receiving a print from a plate cylinder, a slight difference in position is easily generated and a ghost print is formed. In this regard, it is necessary to reduce the pressure of the roller and reduce the expansion and contraction coefficient of the blanket during imprinting to prevent ghosting failure from occurring. In addition, for the use of aging blankets, should be replaced with a new blanket for printing, to eliminate print ghosting failure.
The printing pressure of the lithography process does not cause ghosting failures, and the embossing process does. When the embossing process employs a multi-layered glued board as a printed bottom mat for printing a large area of ​​a plate product, due to unevenness of the bottom mat and poor solidity, the printing plate vibrates during printing to cause ghosting failure. In this regard, the elimination of measures is that the bottom pad should be flat, the bottom plate should be planed into four sides straight edge, right angle state, so that the plate is firmly attached to the bottom plate after the close, to eliminate the plate "hanging" caused by ghosting failure .
Fourth, the dirty pressure caused by excessive printing pressure and paste plate When the printing pressure is too large, the friction surface of the blanket surface on the printing plate must be increased, so that the plateau sand subject to wear and damage, the blank area of ​​hydrophilicity mutates, The ink is attached and transferred to the print, which is a dirty version. In addition, the printing pressure is too large, the elastic deformation value of the rubber under pressure is also large, the transfer of the imprint is also easy to produce deformation, especially the printing of dots and small text, there are often paste problems. This is even more evident if it is a relief process. Therefore, in order to prevent the occurrence of dirty and paste, it is necessary to accurately adjust the printing pressure. According to the equipment specification, the thickness of the liner and the center distance of the drum should be controlled.
5. Ink coloration caused by uncomfortable printing pressure When the unevenness or insufficient pressure of the unevenness of the liner, when printing, between the printing plate and the rubber, between the blanket cylinder and the impression cylinder, or between the plate and the blanket (the relief process) The phenomenon of poor contact will affect the uniform and full transfer of the ink layer on the layout, which will cause the ink of the layout with insufficient pressure to be light and fade. In order to avoid this unfavorable situation, it is necessary to turn off the printing technology of “Sanping†printing, and the printing plate and the ink roller should be leveled, and the bottom pad of the printing plate should be leveled; the plate and the blanket cylinder or the lining (embossing) should be flat. , should be flattened blanket or lining; imprinting roller and rubber roller should be flat, should protect the surface of the impression roller to prevent loss of deformation and flatness, to maintain uniform and adequate printing pressure, is to eliminate the printing ink ink Effective measures.
In a word, printing pressure is the basis of product quality. Only by carefully concentrating good printing operation technology, scientifically and rationally adjusting, and handling various factors affecting the pressure, can we ensure the printing quality of the product. (Kang Qilai) ("China Packaging News")
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