Self-adhesive materials in the die-cutting and waste discharge is not only the basic process of self-adhesive label processing, but also a problem-prone link. Among them, waste discharge and breakage is a common phenomenon. Once the waste discharge and breakage, the operator must stop and re-organize the waste discharge part, which will reduce productivity and increase the loss rate of raw materials. So what are the causes of waste discharge and breakage in die cutting of self-adhesive materials and how to deal with them?
1. Process design is not reasonable or waste discharge is too fine
Currently, many labels on the market for variable information printing have virtual knife lines that are easy to tear. Due to the limitations of the equipment, some self-adhesive label processing companies have to place the virtual knife and frame knife in the same die-cutting position; In addition, due to cost and price factors, the waste discharge edge design is very fine, usually only 1mm width. This die-cutting process on the label material requirements are extremely high, a little carelessness will lead to waste discharge edge breakage, thus affecting production efficiency.
It is recommended that under the conditions allowed, self-adhesive label processing enterprises should try to tear the knife line and labeling framework for die-cutting separately, which not only reduces the frequency of waste discharge and breakage, but also can greatly improve the die-cutting speed. Unconditional enterprises can solve this problem in the following ways.
1) Adjust the proportion of dashed line knife. Generally speaking, the denser the arrangement of dashed line cutter, the more likely to waste easy breakage. Therefore, we can adjust the ratio of the virtual line knife, for example, 2:1 (every 1mm cut 2mm) so that the chances of rows of waste edge breakage will be greatly reduced.
2) Delete the virtual knife line beyond the label frame. In many die-cutting versions, the virtual knife line will discharge longer than the label frame. If the waste discharge edge is relatively narrow, the dummy knife will cut off the already narrow waste discharge edge, causing the waste discharge edge to break easily. In this case, the dashed cutter protruding beyond the label frame can be filed off with a sharper file, which greatly improves the strength of the waste discharge edge and makes the waste discharge edge less prone to breakage.
2. Low tensile strength of raw materials
Some materials, such as light powder paper (also known as mirror coated paper), short fiber, relatively fragile. In the die-cutting and waste discharge process, the tensile strength of the edge of the waste discharge is lower than the waste discharge equipment tension, easy to break.
In this case, it is necessary to minimize the waste discharge tension of the equipment. If the equipment waste discharge tension has been adjusted to the minimum, still can not solve the problem, then in the early process design needs to design a wider waste discharge edge, to ensure that the waste discharge edge in the die-cutting process will not break frequently.
3. Material breaks
The breakage of self-adhesive material is also easy to cause the waste discharge edge breakage. This problem is easy to find. This article will not be repeated. It should be noted that some self-adhesive materials have relatively small edge breaks that are not easy to find and require careful observation to find. If this type of problem occurs, remove the defective material before die cutting.
4. Die cutting knife defects
Defective die cutting knives can easily lead to waste discharge edge breaks. For example, there is a small gap at the edge of the cutter, which will result in the non-dry rubber surface material not being completely cut off. Compared to other parts, the force of the uncut part is more concentrated and prone to breakage. This phenomenon is easier to determine because the location of the break is fixed. In this case, the damaged die needs to be repaired before die cutting.
5. Adhesive fluidity is too strong or the amount of adhesive coating is too large
The amount of adhesive coating in the self-adhesive material has a great impact on the die-cutting performance of self-adhesive materials. Generally in the die-cutting equipment, self-adhesive materials in the die-cutting will not be discharged immediately after the waste, but continue to pass forward for some distance, until the waste discharge station only began to discharge waste. If the adhesive coating is too thick, the adhesive will flow back during the transfer from the die-cutting station to the waste discharge station, causing the cut self-adhesive facing material to stick together again, resulting in breakage due to adhesion when the waste discharge edge is pulled up.
Generally speaking, the coating amount of water-soluble acrylic adhesives should be between 18 and 22 g/m2, and the coating amount of hot-melt adhesives should be between 15 and 18 g/m in 2. For self-adhesive materials exceeding this range, the probability of the waste discharge edge breaking will be greatly increased.
If such a problem occurs, the first thing you can do is to observe whether there is a severe pulling phenomenon between the waste discharge edge and the label. If the drawing is severe, it indicates a large or fluid adhesive coating. This problem can be solved by applying some silicone oil additive to the die cutter or by heating it with an electric heating rod. Silicone oil additives are effective in reducing the rate of adhesive reflue, while heating the adhesive material will soften the adhesive quickly, thus reducing the degree of drawing.
The above are more common some self-adhesive materials label die-cutting in the waste easy to break the situation, if there are other you label printing encountered, welcome to share with Sinopack, together to solve the problem.