Analysis and Treatment of the Causes of Printing Wrinkle Failure

Print wrinkle failure is a common failure phenomenon in the printing production process. The phenomenon of the wrinkling failure of printed products is analyzed. The reasons are various, such as the abnormality of the moisture content of the paper, and the source of the defects in the printing layout; the reasons for the improper lining process and the unsatisfied printing pressure; There are paper grippers that are poorly adjusted or the amount of mouthwash is too small. Therefore, careful analysis of various wrinkling failure phenomena, and correct grasp of the printing operation and process technology are important measures to prevent the wrinkling of printed products from ensuring the printing quality of the product.

I. Analysis and Preventive Measures of Several Phenomenon of Printing Wrinkle Failure

1. Wrinkle failure caused by curling of paper edges

We know that paper is very sensitive to changes in the temperature and humidity of the environment. If the temperature and humidity of the printing environment are not normal, it is easy for the paper to undergo stretching and variability. If the moisture content of the paper is too low, the paper tends to be curled around, and wrinkling may easily occur during printing. If the moisture content of the paper is too low, it is also prone to static electricity and it is difficult to achieve normal printing. If the moisture content of the paper is too high, it is easy to make the paper too soft to cause embossing and wrinkling. Therefore, we should pay attention to strengthening the scientific management of paper at ordinary times. The room temperature of the paper storehouse should be controlled between 18 and 22 degrees, and the indoor relative humidity should be between 60 and 70%. The paper package products entering the warehouse should be unpacked and stacked as soon as possible. Stack the paper away from the ground and away from the wall to prevent the paper from moisture and moisture. In addition, the paper should also be heat-resistant, anti-folding and pressure-proof, which is not only the basic requirement for better prevention of paper warp and deformation, but also the necessary measure to prevent wrinkling of printed products.

2, printing plate structure defects caused by printing wrinkling

Some papers have good flatness, but wrinkling failures still occur during printing. This is due to layout reasons. For example, when printing on-the-spot and letterpress printing, the contact between the printed sheet and the printing surface during the imprinting process easily generates air resistance, which causes the partial sheet of the printed sheet to become convex and wrinkle. In addition, the underplating of the cleats plate is uneven and the bottom brackets are not solid enough to cause the printing pressure to be heavy, which may cause the wrinkling defects of the printed products. This should be achieved by adding a good version of the padding technology and reducing the line layout. Pressure to avoid printing wrinkle failure.

3, wrinkling phenomenon caused by lining discomfort

The lining is the medium of imprint transfer. When the inner and outer lining layers are too soft, the lining is easily pressed after the lining is pressed, and the lining bag is not tight enough. The surface lining paper has a broken condition and the lining surface is covered. Repeatedly padding or air control, pad sticker tails are not sticky and fluttering and other undesirable conditions, are likely to produce printed wrinkling phenomenon. Therefore, the printing process should pay attention to a good lining process technology to prevent the lining because of virtual loose pressure, uneven surface caused by printing products wrinkle failure.

4, printing equipment wrinkles caused by wear and loose parts of equipment

When the critical parts of the machine, plus linked roller for stamping the use of mechanical parts wear, loss of due precision, so that the machine imprinting moment due to the existence of a slight amount of looseness and slippage, which is also printing a certain layout, paper Produces the source of embossed creases. To this end, peacetime should pay attention to strengthening the maintenance and overhaul of the equipment, so that the key parts of the equipment to maintain good lubrication and high accuracy, to prevent the occurrence of axial or radial loose parts between the bad phenomenon, reduce the occurrence of printing wrinkling Opportunity.

Second, a number of printing products wrinkling occurs

1. Knock paper processing to improve the printability of the paper.

For paper that is thin or lacks flatness and stiffness due to deformation, such as the curl of the printed sheet, there must be a physical change in the paper by knocking on the edge of the sheet to improve the printed sheet. The flatness and firmness of the paper edge. As for the phenomenon of curling in the paper surface, a horizontal knocking or vertical knocking may be adopted as appropriate, so that the printed sheet can obtain the flatness required for printing so as to eliminate the wrinkling of the printed product.

2, adjust the printing pressure, eliminate the wrinkle defects caused by printing pressure uncomfortable.

For flexible papers that are prone to creping of printed products, the requirements for meeting the amount of ink on the layout should be considered as far as possible during the printing process to prevent printing ink from being misprinted due to insufficient ink on the layout, resulting in creping of printed products. In addition, the adjustment of the printing pressure should be achieved through the underpad as much as possible, and the underpad should be balanced with the pad. It is necessary to avoid large-scale shimming on the outer lining, and even dug up the outer lining repeatedly. This is also effective in preventing wrinkling of the printed product. Method.

3. Adjust the pressure of the roller gripper and the position of the crepe paper to eliminate the wrinkle-up failure of printed products caused by mishandling of printed sheets. ·

When the uneven pressure of the cylinder or the positioning of the printed sheet is not suitable to make the corners of the paper not align with the teeth, and the bad condition such as the amount of the opening of the printed sheet is too small, it is easy to make the printed sheets in the rolling process and cause the partial paper to slip. The unevenness causes the printing product to wrinkle. To this end, the pressure of the clenching teeth and the position of the printed sheet in the row of teeth should be adjusted so that the edge of the sheet is more likely to enter the bite position, and the amount of the mouth opening is appropriately increased so that the teeth can be bitten by the paper edge to avoid pressure. The occurrence of slippage was eliminated to eliminate the wrinkling problem of printed products.

4, adjust the machine brush device, so that the print service flat close to the roller, eliminating the printed sheet crease caused by falling.

In order to ensure the printing quality, an automatic printing press has a row of flat paper brushing mechanisms at the position of the cylinder imprinting line. When the softer and lighter paper is printed, if the brush presses the printed sheet on the surface of the roller tightly, it will easily cause printing. Wrinkle phenomenon. Should loosen the hair brush properly, it can eliminate the wrinkling problem of printing products.

In short, as long as we carefully sum up experience in practice, we carefully analyze and study the various phenomena of wrinkling of printed products, take various preventive measures, and carry out technical and process control checks from the source of the failure. It can minimize or avoid the various features of printing products wrinkle failure, to ensure product printing quality.

Author (Kang Qilai)