Analysis of five kinds of quality faults of the ho

2022-07-17
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Analysis of five kinds of quality faults of die-cutting indentation

die-cutting indentation is an important production process of post press processing. It is widely used. Die-cutting indentation processing process can be used for cartons, cartons, paper bags and other packaging and decoration printing products. It can be said that the quality of die cutting indentation directly affects the use effect and market image of the whole product. Therefore, it is of great significance to correctly understand and understand some quality faults that are easy to occur in the die-cutting indentation production process, take corresponding process and technical measures, and scientifically and reasonably do a good job in the die-cutting indentation production and quality control, so as to effectively prevent the occurrence of various quality faults and improve production efficiency

I. several fault analysis of inaccurate die cutting indentation position or specification of semi-finished products

1. inaccurate layout specification caused by expansion and variation of semi-finished products. If the stability of semi-finished paper is poor, resulting in obvious variation of moisture content in the printing process, especially after the product is processed by calendering, coating or mounting, the semi-finished product is subject to expansion change due to heat or absorption of moisture, so that the layout position of the printed product will deviate during die-cutting indentation. In this regard, the solution is: try not to use the newly produced paper. The newly produced paper should be placed for several months to make it relatively balanced with the printing conditions before it is put into use, so that its deformation coefficient is relatively small. For products with high precision, the deformation coefficient of calendering, film covering, mounting and other processes shall be fully considered, and the layout position shall be appropriately adjusted during printing. In addition, the temperature and humidity of the paper warehouse, glazing, calendering, film coating, mounting and die-cutting workshops, as well as the temperature and humidity of each production process, must not be significantly different, so as to ensure the accuracy of the position and specification of the die-cutting indentation

2. the thickness changes of semi-finished products after mounting, resulting in inaccurate layout specifications. After the printing semi-finished products are mounted, the thickness change will also affect the layout position of the finished products after the die-cutting indentation. Especially after the corrugated board is mounted, due to the increase of its thickness, the layout position of the products will also appear deviation error after the die-cutting indentation is formed. Therefore, the position of the page should be considered after the product is mounted and folded to increase the thickness

3. the paperboard has obvious curl, resulting in inaccurate positioning of semi-finished products. When the semi-finished products are curled and warped, especially the corrugated board semi-finished products after mounting, are placed on the embossing plate for pressing, the paper surface does not contact the die-cutting plate evenly, so that the warped paper surface first contacts the rubber strip or sponge on the plate, which is easy to cause the semi-finished product printing sheet on the embossing plate to slip, resulting in inaccurate die-cutting of the product. Therefore, maintaining the good flatness of the paperboard is an important step to improve the die-cutting accuracy of semi-finished products. The key to controlling the flatness of the corrugated paperboard is to control the production process of the single-sided machine, select the one with the similar moisture content of the corrugated paper and the box board for supporting production, and control the speed and temperature of the single-sided machine, so as to prevent the obvious curl of the corrugated paperboard from affecting the die-cutting accuracy of the product

4. the positioning error of semi-finished products is caused by inaccurate mounting of upper and lower paper. If the two layers of paperboard on the printing surface and non printing surface are not mounted correctly, the non printing surface paper will protrude from the regular paper edge of the printing surface, which is bound to cause die cutting positioning error of semi-finished products. The daily production situation shows that whether it is manual mounting or mechanical automatic mounting, it is inevitable that there will be inaccurate mounting. In order to prevent the regular paper edge of the non printing surface from protruding after mounting, it is generally necessary to add an edge trimming allowance of 3 ~ 6mm to the side gauge and front gauge paper edge of the semi-finished product during printing according to the characteristics of the product. In this way, when mounting, the regular paper edge of the non printing surface shall be appropriately reduced by several millimeters, It can effectively prevent the regular paper edge of non printing surface from protruding, and ensure the accuracy of product die cutting

5. the positioning of semi-finished products is inaccurate due to poor machine. If the multi-material functional composite of die-cutting machine has gradually become one of the important technical means to improve the performance of automotive non-metallic parts, it is also easy to cause inaccurate positioning of semi-finished products when some parts are worn and loose. In this regard, the machine should be carefully observed and checked, and corresponding measures should be taken to deal with the existing adverse conditions to ensure the accuracy of product die cutting

6. the die cutting indentation plate is loose and deformed, resulting in inaccurate position and specification of the plate. Due to the high pressure of die-cutting indentation, if the plate frame is not used to install the plate due to the large size of the plate, the fastening of the plate is not very firm. In this way, it is easy to move the die-cutting plate along the horizontal position of the plate table during the production process. In addition, under the action of great pressure, the die-cutting plate may make the plate core become solid, and the steel blade is also prone to bending and other adverse conditions, which will also change the specification of the die-cutting plate and affect the die-cutting accuracy of the product. Therefore, careful observation and inspection should be paid attention to during the production process, and measures should be taken to correct the problems found in time

7. the rubber strip or sponge is too thick, resulting in inaccurate die cutting. The function of rubber strips and sponges is to use elasticity to quickly separate and peel the semi-finished products and their leftovers from the die-cutting plate, so as to achieve continuous and normal production. Generally speaking, the rubber strip should be 3 ~ 5mm higher than the knife edge, and the sponge block should be more higher than the knife edge. It should be reasonably mastered according to the characteristics of the product to achieve better results. During production, it must be noted that if the flatness of semi-finished products is poor and the rubber strip or sponge is too thick, it is easy for the rubber strip and sponge to rub the warped paper surface first during pressing, which will shift the printing sheet and cause inaccurate die cutting

8. incorrect position of die cutting indentation caused by misdirection of paper grain. There is one problem in the vertical and horizontal layout that is often encountered in experiments. The direction is generally composed of several small versions. If the horizontal strands of paper that are most prone to expansion and contraction change are used to print the layout in multiple directions, it is easy to cause inaccurate die cutting. Therefore, the layout has always been a multi plate combined structure, and the longitudinal thread of the paper should be used to print, so as to better ensure the accuracy of die cutting

II. Analysis of bursting failure of the indentation line of semi-finished products

1. the indentation line bursts due to excessive die-cutting pressure. How to control the pressure of die cutting has a great impact on the product quality. In case of uneven pressure, in order to completely cut off the leftover materials, if the pressure is blindly increased to achieve the goal, it is easy to cause the pressure at the indentation line to be too heavy and burst. In order to ensure that Russia is still the largest importer of extruders in China, the die-cutting pressure is uniform. It is forbidden to mix new and old steel knives with steel wires. The pressure of steel knives and steel wires must be uniform and appropriate. Attention should be paid to the overall consideration during the plate padding, and the plates should be padded separately to prevent the indentation line from bursting

2. the paper is too dry, causing the indentation line to burst. Offset line, glass card, white board and other papers are fragile. If the moisture content is low, the indentation line is easy to burst. Therefore, attention should be paid to the control of temperature and humidity

3. local bow of die-cutting plate or embossing plate causes the indentation line to burst. When the edge of the die-cutting plate is not square enough and there are beveled edges, the fastened plate is prone to bow; Excessive tightening of the die-cutting plate, as well as local deformation and bowing of the iron plate on the embossing plate, will cause the indentation line to burst. The controlled parts have the function of power-off memory, so that the edge of the die-cutting plate should meet the requirements of right angle and squareness. In this way, it is not easy to cause the bow of the plate after fastening, and it can prevent the indentation line from bursting

4. the indentation line burst due to poor machine. Some important parts of the machine are subject to vibration and other adverse phenomena due to wear and excessive clearance, resulting in unstable work of the pressing parts of the machine, which may cause occasional burst of the indentation line when the pressure is light or heavy. In this regard, it is necessary to find out the cause of the machine failure and take corresponding repair measures to prevent the indentation line from bursting

5. the indentation line bursts due to the displacement of the master pad. Due to the effect of pressure, vibration and other factors, during the die-cutting process, the pad paper block is easy to move, making the local indentation line higher, causing the indentation line to burst. In order to avoid this situation, the pad paper must be glued firmly, and the product should be carefully inspected during production

6. the indentation groove is too narrow or the paste is skewed, causing the indentation line to burst. When the indentation groove is too narrow or the paste is skewed, it is also easy to cause the indentation line to burst. Therefore, according to the thickness of the indentation steel wire cutter, the cutter slot with corresponding width shall be selected, and the position of the cutter slot shall be accurate to prevent the indentation line from bursting

7. the paper block adhered to the imprint plate caused the indentation line to burst. During the production process, the leftover materials falling off adhere to the iron plate, which will also cause the indentation line to burst. In this regard, attention should be paid to inspection and cleaning to prevent the indentation line from bursting

8. the thickness of the indenting steel wire cutter is inappropriate, resulting in the bursting of the indenting line. For thick semi-finished products, if the thickness of the indentation steel wire cutter is too thin, the product is easy to burst after folding at the indentation. Therefore, appropriate thickness of the steel wire cutter should be selected according to thickness of the product, so as to better prevent crack of the indentation line. (to be continued)

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