The use and maintenance of blanket

The protection and maintenance work during the use of the blanket is the basic work that the offset printing operator must constantly work on. This helps to print clear and full images, avoid failures, reduce downtime, and also help extend the life of the blanket. .

Offset blankets are responsible for transferring the ink on the plates to the paper. To make the prints uniform in ink, clear dots, and rich layers, offset blankets must not only possess suitable hardness, small compression deformation, good ink transfer performance, and flexibility. Small physical properties; but also chemical properties that do not react with chemical potions and various oils.

The manufacturing quality of the blanket itself has an important relationship with the quality of the printed matter. The elasticity of the blanket is good, the hardness is suitable, the compression deformation is small, and the abrasion resistance is good. Therefore, the graphic quality is high in the printing process; otherwise, the printing quality is high. Can not guarantee. However, during the offset printing process, even if the quality of the blanket is good, improper use and maintenance will also cause print quality problems and shorten the service life of the blanket.

1 The use of blankets

The blanket consists of a surface layer and a base fabric, and is divided radially and horizontally. Since the extension of the blanket after the radial force is smaller than the transverse direction, the radial direction in which the expansion and contraction amount is small must be taken as the force direction of the blanket, that is, the radial direction of the blanket coincides with the circumference of the drum. When the blanket is cut, all four sides should be at right angles, and the diagonal line should be equal. In this way, the blanket can be evenly distributed on the roller to ensure product quality. At the same time, the bite of the blanket and the two ends of the tug are punched separately. The position of the hole should be on the same horizontal line, and there should be no height to prevent the blanket from being skewed.

When the new blanket is installed on the machine, it should be tightened first, and then check the blanket for wrinkles and air bubbles. If there is no problem after the inspection, tighten the roller after pressing the pressure several times. The new blanket has good elasticity and good stretchability. Tensile blankets should be gradually carried out. It is required that the tipping and the bite of the mouth should be performed at the same time. Do not apply tension on one side. Each time it is tense, it will wait for 3 to 5 minutes to pressurize and pressurize, so that it can be tightened several times. After the blanket has been tightened, we should also visually or manually stroke the blanket to check if the blanket and its cushioning material are flat, whether there is unevenness caused by the ink, paper, etc., and handle it in time.

Before the new blanket is put on the machine, the thickness of the desired pad should be determined according to the specific thickness, uniformity, elasticity, etc. of the blanket, and the number of liners should be determined with a micrometer. Over-thick gaskets will cause greater pressure between the blanket and the plate, affect the printing quality, make the imprints thicker and more distorted, and the dots will expand, and it will cause premature damage to the blanket. In addition, it will also speed up the printing plate. Graphic wear.

2 blanket storage requirements

1) The blanket should be stored in a cool, dry environment, away from heat sources and direct sunlight to prevent desulphurization. In order to ensure good air circulation, each blanket should be hung on the mast. If the warehouse is narrow, the blanket should be placed flat, do not press heavy objects on it, and the blanket should not be rolled into a tube when it is best preserved.

2) Open the blanket packaging, remove the protective cover, and carefully inspect the blanket for damage. It is not advisable to install a new blanket directly on the machine. Since the blanket is wrapped in a roll, it should be laid flat for a period of time so that it can gradually return to level before it can be used on the machine.

3) If you stack a lot of blankets, stack the blankets face to face or back to back, otherwise the fiber pattern on the back of the blanket will affect the flatness of the other blanket surface.

4) Do not cause the blanket to be squeezed so as not to damage the blanket or destroy its elasticity. The blanket is afraid of light and heat and moist air. They will make the surface of the blanket sticky, crusted, cracked, and hardened. .

5) The storage warehouse should be ventilated and dry, the relative humidity should be about 70%, and the temperature should be about 24°C. Save the rubber blanket and do not touch the acid and alkali, oxidants, and petrochemical products to avoid the erosion of chemicals on the blanket.

3 blanket maintenance

1) The correct washing blanket can prolong its service life. It is necessary to cultivate civilized production work habits. After a product is printed, oil on the blanket, paper hair, debris, ink blots, wetting fluid, etc. should be used in time. The blanket cleaner is cleaned and wiped clean.

2) Prevent the blanket from being deformed by pressure. In the normal operation of the offset press, the blanket is fully and evenly pressed, so there will be no compression and deformation at any location. If the machine is deactivated for a long time, remove the blanket and lay it on the table to prevent the rubber layout from being deformed under pressure.

3) A good blanket cleaning reductant can not only play the role of cleaning the clean blanket, but also can restore the surface of the blanket, flat clothing, and restore its elasticity. The blanket cleaning reductant cannot be evaporated too quickly, otherwise it will cause trouble for the operator.

4) Because the blanket is subjected to long-term penetration of gasoline, varnish, and ink during the printing process and is periodically stretched and squeezed under pressure and relative friction, the blanket will lose sulfur, become sticky, and deform. , And lack of good flexibility, thus affecting the quality of the transfer, at this time we must replace the new blanket.

Reproduced from: Wins