The causes and solutions of cigarette mark die cutting burrs

At this stage, China's tobacco label printing is booming. In terms of the accuracy and grade of its equipment and cigarette pack products, it can almost be said to have become the highest level in the domestic packaging and printing industry. Therefore, as a first impression, the appearance of cigarette label products should not be flawed. This article focuses on the common problems of die-cut burrs in the production process of cigarette labels, and talks about the experience and experience.

1 Causes of die-cut burrs

During the die-cutting process of cigarette labels, due to various reasons, filament, powder or jagged paper scraps, colored ink powder or white spots remain on the incision of the steel knife on the cigarette label. . The main causes of die-cut burrs are as follows:

1) Improper selection of die-cutting steel knife or defects in the quality of the steel knife itself, and the phenomenon of curling defects on the blade edge, resulting in obvious burrs on the edge of the die-cut product.
2) The overall pressure was adjusted too high during plate installation, and the steel blade edge was crushed.
3) No partial decompression after partial tool change, resulting in overpressure of the new knife and damage to the blade.
4) Due to the special nature of the tobacco standard products, long-term mass production is required. During the production process, the steel knife will have different degrees of natural wear. At this time, the product is forced to be broken rather than the blade cutting through. Raw edges.
5) The pressure is not enough, the paper is not cut through, but is torn when removing the edge of the waste paper.
6) The steel plate at the bottom of the moving platform will produce a knife groove after long-term use. The rough knife groove is very easy to seriously damage the steel knife, which will cause burrs.
7) The hardness and height of the rubber strip on the knife side are not suitable or the sticking distance is unreasonable. If the hardness is too low, the height is not enough, or the paste is too far, the paper cannot be effectively compressed; if the hardness, height, or paste distance is too close, the paper is forcibly pulled and broken by the tape when the knife is not completely cut, which will cause burrs.
8) When the distance between the knife and the steel wire is too small, the paper will form a pull between the rubber strip and the indentation bottom film, and it will also cause paper burrs.
9) The die-cutting suitability of the paper itself will also lead to the occurrence of burrs to a certain extent. For example, gold and silver composite cardboards are prone to silk-like burrs, while white card glass cardboards often have powdery burrs; paper with shorter fibers Low-cost but prone to burrs, paper with longer fibers is relatively rare, but the cost is higher.
10) At this stage, most of the base molds of flat-press flat-cut die-cut plates use 18mm thick multi-layer composite glue wood board. In theory, the texture, uniformity and resistance to deformation of the board will also indirectly cause burrs through the influence of the angle when the die-cut steel knife is cut.

2 Solution

1) Choose a suitable steel knife. For high-volume production, try to use high-quality cross-grained short-edged knives treated with coatings, one to prolong the service life of steel knives, and the other to avoid burrs. When the steel knife is found damaged, it should be replaced with a new knife in time. If the blade is damaged or slightly curled, use fine sandpaper to dip an appropriate amount of engine oil and gently smooth the blade along the sides of the steel knife, but be careful not to wear the blade directly from the front.
2) Due to mechanical and other reasons, the pressure during die cutting and adjustment cannot be absolutely balanced and consistent, and the appropriate initial pressure should be selected according to the actual situation. Rather than frequently dealing with burrs in the production process, which causes quality defects and wastes a lot of time, it is far better to use a lower overall pressure from the beginning and spend more than half an hour to gradually pad the adhesion.
3) After the old knife has been worn for a long time, the blade is actually shorter than the new knife, and the required pressure is higher. Therefore, after replacing the new knife, pay attention to the local decompression immediately, and then increase or decrease the pressure according to the actual situation to just cut through .
4) We should continue to explore and verify in the company's production practice, sum up the service life of the knife die steel knife under normal conditions, formulate knife die monitoring management standards, and strictly replace the full set of new knifes in time according to the standards, or even replace the new knife die . When formulating this standard, we must adhere to the basic principle of "both fully guarantee product quality and not cause unnecessary waste".
5) Strengthen the machine's random inspection, if it is found that there are sticky burrs, local pressure should be applied immediately. Special attention should be paid here to distinguish whether the burr is caused by insufficient pressure or sticky burr caused by insufficient pressure, or is caused by the pressure of the steel knife due to excessive pressure, and different treatment measures are taken. Otherwise, it will not only be unsolvable, but also counterproductive, making the burr phenomenon more serious.
6) Before installing the plate or when there are burrs in the production process, the bottom steel plate should be carefully checked. The slight sipe can be smoothed with sandpaper, and the steel plate needs to be replaced seriously (if the conditions permit, the bottom steel plate can be replaced or used by the professional company as a whole Grinding), the burr is not serious when the sipe is slight and smooth, but when the sipe is too deep, especially when the sipe is irregular or the knife and the sipe are not fully aligned and matched, 100% of the burrs will appear severe, even if the knife is changed frequently Effectively solved.
7) Select the appropriate adhesive strips according to actual needs. Generally, the sticking position of the rubber strip should be about 1mm away from the steel knife. The general selection criteria for rubber strips are as follows: when the distance between the die-cutting blades is less than 8mm, choose a white solid rubber strip with a hardness of 60 degrees Shore hardness, and when the distance between the die-cutting blades is greater than 10mm, choose a gray breathable sponge rubber with a Shore hardness of 35 degrees When the distance between the die cutter and the steel wire is less than 10mm, a white arched rubber strip with a Shore hardness of 70 degrees should be used. However, I personally think that the only standard for the selection of rubber strips in practice is the actual effect, which needs to be handled flexibly according to the actual situation in production. Most of the burrs generated due to the rubber strip are not sufficiently hard. Generally, it can be solved after replacing the rubber strip with a higher hardness (for example, if there is an indentation mark after switching to a hard rubber strip, a softer rubber strip is tightly adhered to the side of the hard rubber strip That is, it can serve as a buffer transition).
8) In practice, cigarette standard knife molds use hard, even and high-quality base boards, even plastic template and steel template, so it is not uncommon in cigarette label production to cause burrs due to knife mold base materials.
9) When using short-fiber paper for cost purposes, you can consider using a high-front straight-line knife that is easy to smooth and cut the paper, but at this time, the die-cutting pressure needs to be strictly controlled to avoid damage to the fragile high-front blade.
10) Hongye Equipment recently introduced and promoted the German COMAT (Kangmai) die-cutting equalizing pressure device (to "sandwich" the moving platform steel plate). In addition to its main purpose of "substantially shortening the bottoming working time", personally think that it can pass Balanced pressure strengthens the protection of steel knives, etc., and simultaneously reduces the probability or severity of die-cutting burrs from several aspects. [next]

3 Special case analysis

1) Phenomenon of a certain cigarette label product, using a certain brand of white card backing paper, partial transfer of laser silver, gravure printing, partial UV, automatic flat-press die-cutting, and 18 single-tools. When the new knife mold produced about 200,000 sheets, it began to show obvious burrs on the outer edge of the glue knife. The local pad pressure was slightly improved, but short-term frequent burrs began.

2) Observation and analysis After observation, the burrs all appeared on the white background outside the glue knife, "ears" and "tongues", and the cuts on the colored inks were smooth and smooth. The blade at the raw edge is obviously dull. The most unique thing is that even with the same steel knife, with colored ink as the boundary, the edge of the colored ink side is intact, and the edge of the colorless ink side is severely blunted and whitened. According to this analysis, the reason for the burr is that the knife edge at the exposed bottom is not lubricated by ink and UV varnish, which causes the relative wear of the steel knife to increase.

3) The processing method is changed on the original local varnish roller of the gravure printing, and a varnish belt with a width of 2 mm is printed on all parts of the die cutter that have not been varnished. The mass production practice in the following year proved that after this treatment, the burr problem of the product was completely controlled.

4) Conclusion Whether it is to solve burrs or other die cutting quality technical problems, the method may be known or unknown. There is no real "million oil" in the world. The most important thing is to constantly observe and think, find anomalies and summarize the laws. This is the way to solve problems and improve technology.

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