1、 Improper ink adjustment, too high ink viscosity, unstable position of front gauge of printing sheet

        Practice shows that maintaining the appropriate viscosity of ink is an important condition to ensure the quality of printing products. Ink without a certain viscosity can not print an ink layer with firm coloring, fullness and good brightness. However, there is no unified standard for ink viscosity.Analysis And Elimination Of Inaccurate Embossing Printing

       In printing, the viscosity of ink can only be adjusted by experience according to the characteristics of printing materials (substrates) and printing layout structure. If the viscosity is adjusted too low, the rubber roller will slip, resulting in uneven ink transfer and ink distribution, Analysis And Elimination Of Inaccurate Embossing Printing

      And there will be “oil flower” on the print layout. If the ink viscosity is too high, the printing sheet in the embossing is easy to be stuck and pulled by the ink and slip with the drum, resulting in the failure of inaccurate positioning of the front gauge. Analysis And Elimination Of Inaccurate Embossing Printing

      For example, when dt4oo four opening automatic platform printer is printing a large-area field version, if the ink viscosity is too large, it will have a strong pulling effect on the printing sheet on the drum, Analysis And Elimination Of Inaccurate Embossing Printing

     causing the printing sheet to slide outward from the paper bite teeth, and the front gauge error can reach about 3mm, which has serious adverse consequences. Analysis And Elimination Of Inaccurate Embossing Printing

      In order to prevent this failure, when printing relief products with large ink absorption, an appropriate amount of debonding agent or ink blending oil can be added according to the ink viscosity to reduce the adhesive force of ink on the printing sheet and ensure the printing accuracy.

2、 The adjustment of printing pressure has an impact on printing quality

       Printing pressure is an important factor to realize uniform transfer of imprint. The ideal printing ink layer comes from moderately balanced printing pressure. Generally speaking,Analysis And Elimination Of Inaccurate Embossing Printing

      when the substrate surface is rough and the printing format is large, the printing pressure should be increased accordingly. Analysis And Elimination Of Inaccurate Embossing Printing

        However, in practice, we can not blindly increase the printing pressure to meet the visual effect of printing ink layer. The excessive adjustment of printing pressure not only accelerates the wear of machine and printing plate, but also prone to overprint misalignment. Analysis And Elimination Of Inaccurate Embossing Printing

      This is because when the printing pressure is too high, on the one hand, it will deform the printing sheet and enlarge the printing page, resulting in inaccurate overprint; On the other hand, if the printing pressure is too large, the impression will have a compressive tensile force on the printing sheet on the drum, resulting in the sliding of the printing sheet from the paper teeth, Analysis And Elimination Of Inaccurate Embossing Printing

       which will make the positioning of the front gauge unstable and small. In order to avoid such adverse consequences, the pressure adjustment of letterpress printing should be gradually pressurized from light to heavy when the ink supply of the layout is normal, so as to accurately adjust to the appropriate printing pressure, so as to ensure the printing quality.Analysis And Elimination Of Inaccurate Embossing Printing

3、 The printing plate bottom support is not solid, and the poor flatness and compressive strength cause inaccurate printing

       The hardness and accuracy of the plate holder (adhesive plate bottom holder) used in relief printing greatly affect the printing accuracy of the product. Analysis And Elimination Of Inaccurate Embossing Printing

      If the traditional glued plate is used as the plate support for large-scale field relief printing, compression deformation is easy to occur due to the poor flatness, fastness and compressive performance of plywood. Analysis And Elimination Of Inaccurate Embossing Printing

       In the printing process, the printing pressure is bound to increase due to uneven pressure or empty bottom support, which is easy to cause the deformation of the print layout and make the printed layout larger than the actual version. Analysis And Elimination Of Inaccurate Embossing Printing

        In addition, because the wooden bottom support is easy to bow, the printing sheet taken away by the roller will inevitably slip due to the slight vibration or movement of the printing plate, resulting in the misalignment of product overprint. Analysis And Elimination Of Inaccurate Embossing Printing

       Therefore, when printing plates with large format and high pressure, it is appropriate to use magnetic plate table or aluminum plate holder, which can better ensure the overprint accuracy of products.Analysis And Elimination Of Inaccurate Embossing Printing

4、 Control the lining process technology to prevent overprint inaccuracy caused by printing deformation

       Lining is a bridge to realize the transfer of layout imprinting, which has a certain impact on the printing accuracy. Due to the differences in equipment structure, the requirements for lining thickness are also different. Only by strictly controlling the lining thickness of the machine in accordance with the specification parameters of the printing machine can we ensure that the printing layout is not out of shape. Analysis And Elimination Of Inaccurate Embossing Printing

      If the lining thickness is not enough, the longitudinal dimension of the printed plate is often less than the corresponding plate length; If the lining thickness exceeds the specified parameters of the equipment, the printed layout will be larger than the actual format of the printing plate, which is another factor affecting the printing accuracy. Analysis And Elimination Of Inaccurate Embossing Printing

      In addition, if the lining is not tight enough, there are phenomena such as virtual looseness, bulge and large-area patching of the outer lining, or when the paper is padded, only one side of the biting part is pasted, and the trailing tip position is not pasted in one case, 

      allowing it to float, which will also cause the enlargement and deformation of the print layout and printing inaccuracy. In order to ensure the accuracy of letterpress printing, it is advisable to use neutral and hard packing liner, and wrap the packing liner tightly.Analysis And Elimination Of Inaccurate Embossing Printing

5、 Misadjustment of the paper teeth of the drum causes inaccurate positioning of the printing sheet  Analysis And Elimination Of Inaccurate Embossing Printing

       When printing the field version, if the roller bite pressure is insufficient, the printing sheet is easy to slide out of the bite due to a certain degree of anti stripping resistance caused by the ink viscosity of the layout. Analysis And Elimination Of Inaccurate Embossing Printing

      For example, dt400 four opening automatic platform printing machine is prone to the above disadvantages when printing large-area field relief products. Analysis And Elimination Of Inaccurate Embossing Printing

       The main reason is that the spring steel plate pressure of the original drum bite is not enough, so that the bite can not bite the edge of the paper. The author has added steel sheets to the roller teeth, so as to bite the printing sheet tightly, prevent the printing sheet from sliding and moving during embossing, and better ensure the printing accuracy.Analysis And Elimination Of Inaccurate Embossing Printing

       In addition, the machine also has another disadvantage affecting the positioning of printing sheets, which is worthy of attention. Analysis And Elimination Of Inaccurate Embossing Printing

       That is, after the printing sheet enters the drum to bite, at the moment when the bite closes and takes the paper, one end of the printing sheet sometimes retreats slightly, resulting in printing skew. Analysis And Elimination Of Inaccurate Embossing Printing

      The main reason is that there is ink or agglomerated paper dust in the bite corresponding to the skew edge. When the bite is closed, the dust raised in the bite just hits the edge of the paper,Analysis And Elimination Of Inaccurate Embossing Printing

      resulting in inaccurate positioning of the front gauge. As long as the dust accumulated in the paper biting teeth is cleaned, the fault can be eliminated.Analysis And Elimination Of Inaccurate Embossing Printing

      To sum up, good operation and process technology can not only effectively ensure the printing quality of relief printing and improve the printing accuracy of products, but also better improve the production efficiency of enterprises.Analysis And Elimination Of Inaccurate Embossing Printing