Die cutting indentation of five types of quality failure analysis II

Third, the rough edge of semi-finished die-cut lines

1. Deformation and dulling of the edge of the die-cutting steel blade cause rough edges on the die-cut line of the product. Due to the excessive pressure, the increasing number of die-cuts, and sand grains on the semi-finished products, it is easy to deform the blades of the steel blade and become blunt, resulting in rough edges at the edge of the die cutting line. Therefore, the pressure of the edge of the steel blade should be controlled with as little pressure as possible to cut off the scrap. In addition, steel blades that have been deformed and dulled should be replaced in time to ensure that the edge of the product is clean and smooth.

2. The presence of knife marks on the imprinting plate causes a rough edge on the die-cut line of the product. If the imprinting plate is used for a long time, there are densely stenciled marks, and it is easy to make the edges of the product die cutting line appear rough. In this regard, new iron plates should be replaced in order to eliminate the rough edges at the edges of the product's die cutting lines.

3. Repeated patching of the embossed plate results in rough edges on the die-cut lines of the product. When the press plate is repeatedly patched with a piece of paper to increase the pressure, the surface is uneven and the flatness is poor, which can also cause the product to have a rough edge on the die-cut line. In order to avoid the existence of this situation, a new steel blade should be replaced in the die cutting of the local edge wear of the steel blade to avoid repeated application of partial pressure undercuts on the platen to ensure the product edge Bright and clean.

4. Excessive hardness of the rubber strip causes deformation of the edge of the die-cutting steel blade, and rough edges appear on the edge of the die-cut line. If the rubber strip is too hard or too thick, the combined pressure will inevitably produce a strong compressive force on the edge of the steel blade, which will cause the blade edge of the steel blade to be easily deformed and cause the appearance of rough edges on the edge of the die cutting line. In this regard, you should choose a soft rubber strip, and reduce the thickness of the rubber strip as appropriate.

Fourth, the semi-finished product indentation line is not clear, the collapse of the phenomenon of poor deflection

1. Die pressure is not stable or too small to cause indentation. When the parts and components of the machine are worn out and loosened, the stroke of the press roller or the platen each time is inconsistent, and there is a phenomenon of lightness and heavy weight. When the pressure is light, the indentation line of the product is not clear. In this regard, the equipment should be properly repaired to ensure uniform die-cutting pressure.

2. The width of the indentation sipe does not contribute to indentation or inaccurate crease lines. If the width of the indentation sipe is too large, the indentation line is likely to be unclear, and the product tends to be deflected after folding. Therefore, the width of the sipe can only be matched with the thickness of the steel knife to ensure the clearness of the indentation and the accuracy of the crease line.

3. Indentation steel knife thickness does not cause deflection of the semi-finished product. When cutting thicker products, such as corrugated cardboard, if the thickness of the indentation steel wire cutter is too thin, the pressure on the paper crease line at the crease part of the printed product is not enough. When folding, the crease is at the paper surface. It is prone to bulge due to "stacking paper", resulting in skewed products after folding. Therefore, when the thickness of the die-cut product is large, the thickness of the steel wire cutter is also correspondingly larger, so that the indentation of the semi-finished product is “crushed”, so that the edge of the crease is less likely to generate a “stacking” phenomenon and can prevent the finished product. Skew after folding.

4. The rubber strips are too dense and too thick to make the indentation lines unclear. When the aging precision of the machine is poor, if the rubber strips are over-tightened or over-thickened, the resistance due to the pressure will be large, which will inevitably affect the uniformity and stability of the pressure, and will also cause the indentation lines to be unclear. Therefore, the density and thickness of the rubber strip should be appropriate to make the die-cut indentation pressure uniform.

Fifth, the reason why the die-cutting pressure is not stable due to unstable edge

In the process of die-cutting and indentation, if the trimmings can sometimes be cut off and cannot be completely cut off, this phenomenon is also common in production. The main causes are:

1. The precision of the equipment is not high, and the stroke of each pressure-compressing mechanism is inconsistent, and there is a difference in the pressure.

2. The die-cutting layout is relatively large, and the pressure of steel cutters and steel wire layouts is difficult to fully take into consideration, resulting in uneven and unstable pressure, and the pressure tends to fluctuate when die-cutting.

3. Rubber strips are too dense and too thick, and the material elasticity is unstable. As a result, the working pressure of the pressure-compressing mechanism is large and the pressure is unstable.

4. The four sides of the die plate are not square enough, and there is a hypotenuse. After fastening, the layout is prone to bowing. In this way, the local layout of steel knives will appear high and low in the pressure process;

In summary, in the production process, the quality failure of die-cutting and indentation is various, and the cause of the failure is also multi-faceted. The presence of one or more undesirable factors can cause the occurrence of die-cutting indentation failure. Affect the quality of the product. Therefore, in the daily die-cutting production process, only by carefully summarizing the production experience, and effectively operating the technology and process technology, scientific and rational production, in order to effectively prevent this or that fault occurs to ensure the quality of die-cutting products.

Source: "China Printing" Author: Kai Kang