Die-cut indentation is an important production process of post-press processing, and its application is very extensive. Cartons, paper boxes, paper bags and other packaging and decorating printing products can all adopt die-cutting and indentation processing technology. It can be said that how the quality of die-cutting indentation directly affects the use effect and market image of the entire product. Therefore, correctly understand and recognize some of the quality defects that are likely to occur in the production process of die-cutting indentations, adopt appropriate technological measures, and do scientific and reasonable die-cutting indentation production and quality control to effectively prevent various quality defects. Occurrence and improvement of production efficiency are of great significance.
First, the semi-finished die-cutting indentation position or specification of a number of fault analysis
1. Semi-finished telecommutation variation results in inaccurate layout specifications. If the paper semi-finished products are poor in paper stability, the moisture content in the printing process will fluctuate significantly, especially after the products have been subjected to calendering, laminating or gluing processes, due to heat or moisture absorption, the semi-finished products will undergo telescopic changes. When die-cutting indentations like this, the position of the layout of the printed product will be deviated. In this regard, the solution is: try not to use just the production of paper, freshly produced paper should be placed for a few months to make it relatively balanced with the printing conditions and then put into use, so that its deformation coefficient is relatively small. For products with higher precision, the coefficient of deformation of processes such as calendering, laminating, and gluing shall be fully considered, and the position of the layout shall be appropriately adjusted at the time of print imposition. In addition, it is necessary to control the temperature and humidity of the paper warehouse, coating, calendering, laminating, laminating, and die-cutting workshops, and the temperature and humidity of each production process. There shall be no significant gap between the levels to ensure the location of die-cutting indentations. And specifications are accurate.
2. After the semi-finished product is attached, the change in thickness causes the layout specification to be inaccurate. After printing the semi-finished products, the change in thickness will also affect the position of the finished layout after die-cutting and indentation. In particular, after the corrugated cardboard is inserted, due to its increased thickness, the layout of the product will be biased after die-cutting and indentation forming. error. Therefore, the print imposition should take into account the position of the layout where the product is folded after the thickness of the product is increased.
3. There is a noticeable curling of the cardboard that results in inaccurate positioning of the semifinished product When the semi-finished product is curled or curled, especially after the corrugated cardboard half product after the stencil is placed on the platen, the paper surface and the die-cut plate are not in uniform contact, so that the warped paper surface and the layout are first The rubber strips or sponges are in contact with each other, so that the semi-finished printed sheets on the embossing plate are liable to slip, resulting in inaccurate die cutting. Therefore, maintaining good flatness of cardboard is an important part of improving the precision of semi-finished die-cutting. The key to controlling the flatness of corrugated paperboard is to control the production process of single-side machine, and to select the moisture content of corrugated paper and cardboard. Closely matched production and control of the speed and temperature of the single-sided machine to prevent the crimping of the product from affecting the die-cutting accuracy of the corrugated board.
4. The upper and lower paper magazines are not allowed to cause positioning error of semi-finished products. If the two layers of cardboard on the printing surface and the non-printing surface are not accurately affixed, the non-printing surface of the paper will protrude beyond the edge of the printing surface, which will inevitably result in the positioning error of semi-finished products. Daily production shows that no matter whether it is hand-cutting or automatic mechanical sticking, it will inevitably cause inaccurate phenomena. In order to prevent the non-printing surface of the post-printing paper from appearing on the edge of the paper, it is generally necessary to print it. According to the characteristics of the product, add trimming margins ranging from 3 to 6mm to the lateral gauge and the front gauge edge of the printed semi-finished product. In this way, the edge of the non-printing surface should be shrunk by some millimeters. Sticking can effectively prevent the occurrence of convex appearance on the non-printing side of the paper edge and ensure the accuracy of die-cutting.
5. Poor machines cause inaccurate positioning of semi-finished products. If some parts of the die-cutting machine are worn out and loosened, the semi-finished products are likely to be misaligned. In this regard, the machine should be observed and inspected carefully, and appropriate measures should be taken to deal with the existing unfavorable conditions to ensure that the product is die-cut accurately.
6. The looseness and deformation of the die-cutting indentation plate result in inaccurate layout position and specifications. Since the pressure of die-cutting indentation is relatively large, if the plate size is too large and the plate is not used, the fastening of the plate is not very firm. Therefore, in the production process, the lateral position of the die-cut plate along the platen is easy to make. Divert. In addition, under the pressure of die-cutting plate, the plate core may become solid and the steel blade may also be bent. This will also change the specifications of the die plate, affecting the die-cutting accuracy of the product. Therefore, the production process should pay attention to careful observation and inspection, find problems and take timely measures to correct.
7. Excessive thickness of the rubber strip or sponge results in inaccurate die cutting. The role of the rubber strips and sponges is to use elasticity to rapidly separate and shed the die-cut semi-finished products and scraps from the die-cut plate to achieve continuous, normal production. In general, the rubber strip is suitable for the knife edge 3~5mm, and the sponge piece is more than the knife edge, and it should be reasonably grasped according to the characteristics of the product in order to achieve better results. During production, care must be taken to ensure that the flatness of the semi-finished product is not good, and if the rubber strip or sponge is too thick, the rubber strip and the sponge may be rubbed to the warped paper surface first when the pressure is applied. quasi.
8. The misalignment of the paper pattern results in inaccurate position of the die-cut indentation. One direction on the vertical and horizontal planes is generally composed of multiple small editions. If horizontally-stitched papers that are most prone to telescopic changes are used to print layouts in multiple imposition directions, it is likely to cause inaccurate die cutting. Therefore, the layout has always been a multi-version structure, it should use the vertical silk paper to print, in order to better ensure the accuracy of die-cutting.
Second, the semi-finished product indentation line burst failure analysis
1. Excessive die-cut pressure causes the indentation line to burst. How much die-cutting pressure control, a great impact on product quality. If the pressure is not uniform, in order to completely cut off the scrap, if blindly using the full increase in pressure to achieve the goal, it is easy to make the pressure at the indentation line is too heavy to burst. To ensure uniform die-cutting pressure, avoid using new and old steel knives and steel wires in combination. The pressure of steel knives and steel wires must be uniform and moderate. Attention must be paid to the full consideration of pad plates, and pad plates must be separately prepared to prevent them. Indentation line burst.
2. The paper is too dry causing the indentation line to burst. Papers such as offset lines, glass cards and whiteboard papers are relatively brittle. If the moisture content is low, the indentation lines can easily burst. Therefore, attention should be paid to the control of temperature and humidity.
3. The indentation line bursts due to partial bowing of the die-cut plate or embossed plate. When the edge of the die cut board is not square and edged, the clamped version is prone to bowing; the over-tightening of the die cut board, and the local deformation, bowing, etc. of the iron board on the stamping board will all occur. Causes the indentation line to burst. Therefore, the edge of the die-cut plate should meet the requirements of right angle and square shape, so that it is not easy to cause the occurrence of layout bowing after fastening, which can prevent the indentation line from bursting.
4. Poor machine causes the indentation line to burst. The use of some important parts of the machine due to wear and tear, excessive clearance caused by tremors and other undesirable phenomena, resulting in the machine is not stable press work pieces, so that when the pressure is light and heavy will cause the indentation line occasionally burst phenomenon. In this regard, the cause of the machine failure should be identified and appropriate repair measures should be taken to prevent the indentation line from bursting.
5. The offset of the indentation line is caused by the displacement of the pad plate. Due to the effects of pressure, vibration and other factors, during the die-cutting process, the offset printing plate is easily moved to make the local indentation line high, causing the indentation line to burst. In order to avoid this situation, the backing block must be glued and glued. During the production, the product should be carefully checked.
6. The indentation sipe is too narrow or the sticking deflection causes the indentation line to burst. When the indentation sipe is too narrow or stick to skew, it can easily cause the indentation line to burst. Therefore, according to the thickness of the indentation steel wire cutter, a sipe with a corresponding width is selected, and the position of the sipe paste should be accurate in order to prevent the indentation line from bursting.
7. The embossed plate adhered to the block causing the indentation line to burst. During the production process, the peeled off scrap adheres to the iron plate and can also cause the indentation line to burst. In this regard, attention should be paid to checking and cleaning to prevent bursting of the indentation line.
8. Indentation steel knife thickness does not cause the indentation line burst. For thicker semi-finished products, if the thickness of the indented steel wire cutter is too thin, the product will crack when it is folded at the indentation. Therefore, according to the thickness of the product, choose the appropriate thickness of steel knife in order to better prevent the indentation line burst. (to be continued)
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