The hottest screen printing technology III

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Wire printing techniques (III)

(screen printing techniques) with the increase of the types of wire prints, the types of wire materials and wire plates are also increasing day by day. Generally speaking, silk materials were originally borrowed from other industries, and later developed some other types of materials with the needs of silk printing. However, although a variety of non-metallic wire materials have been used in the silk printing industry, such as silk, nylon and polyester, they still can not meet the needs of all tension machine testing packaging belt stretching steps: silk printing. For example, the silk materials used for dye printing or ceramic ink printing must withstand the long-term erosion of ink and solvent, and the silk plates need to be recycled. In order to meet the needs of these silk printing, people urgently need a kind of silk with long service life and good stability, so the silk called "metal wire" in industry was born. Because the diameter of the metal wire is very consistent and can be very thin, it can print the most delicate patterns. At present, the international use of brain computer interface technology in the human brain can better achieve the successful grasp of a specific object (such as a paper cup, ball) under the control of ideas. The hole (eye) of the wire is also very consistent, and it is larger than that of other wire materials. Moreover, unlike non-metallic wires that are easy to absorb ink, its wire does not absorb ink or solvent, so it can get a relatively flat ink film. It has many advantages: frequent replacement of the template will not cause damage to the wire; Ink is also easy to pass through wire; It is especially suitable for printing with ceramic ink, frit ink, Flake Copper ink and dye ink; It can be used for relatively fine operations; The metal wire can get a thicker ink film; Good rigidity, accurate overprint in printing; It can be used for mechanical automation, semi automation or manual printing. In the past, because the metal wire was not easy to stretch and expensive, it was generally only used to make small versions, but now it is increasingly used in medium-sized and large-scale wire versions. Although it is expensive and inelastic, the quality assurance of Jinan gold testing machine is its consistency and unlimited utilization, which reduces the cost on the whole. And correct stretching and printing technology can make up for the shortcomings of poor elasticity. There are two types of braiding of metal wires used for silk printing, namely, plain weaving and twist weaving. Among them, plain weaving is more commonly used, and twist weaving is mostly used in very fine operations. As shown in figures 14 and 15, plain weaving is the superposition of longitude and latitude of a single thread, while twist weaving is the superposition of longitude and latitude of two threads. The silk holes woven by the two weaving methods are square in shape. The silk obtained by twisting method is thicker. Like other wires, metal wires are classified by mesh (the number of wires). In silk printing, only square holes are used instead of rectangular holes. Square holes have the same number of meshes and the same large hole size in the length direction and width direction. The mesh count per inch or centimeter is the number of holes from any line to a distance of 1 inch. For example, No. 80 wire should have 8080 holes per square inch, that is, 6400 holes; 300 wire should have 300300 holes per square inch, that is, 90000 consistent holes. The metal wire is generally marked with "number 80" or "8080", "number 165" or "165x165". Generally, wire types range from 80 Wires/inch (31 Wires/cm) to 635 Wires/inch (250 Wires/cm). However, coarser wires are also available on the market. The lower the number of wires, the larger the hole; On the contrary, the higher the number of lines, the smaller the hole. In silk, the diameter of the wire is in inches or millimeters. The choice of silk depends on the situation of the copied work, the type of ink and the condition of the printing surface. You can buy silk cloth of any size above 1 square foot (0.09 square meter) from a silk printer. Its width can range from 36 inches (91 cm) to about 79 inches (200.7 cm), and its length is unlimited. Stretch wire although the wire is not easy to stretch and fix on the frame, it does not pose a problem to the printer. It can be nailed to the wooden frame, fixed to the floating rod frame (Figure 17), welded and bonded to the metal frame, and fixed to other special frames. Suppliers and manufacturers suggest that it is best to fix on the metal frame when carrying out fine work with metal wire, because the metal frame will not have any deformation. If wooden frames are used, the strength must be better. In practice, wooden frames can generally be treated first, that is, soak the frame in solvent and coat flaxseed oil on the floating rod. When fixing the metal wire, the silk cloth should first fix the longer side of the frame, then the shorter side, then the longer side on the opposite side, and finally the remaining short side. When fixing the silk cloth, it is best to stretch it with a puller (Fig. 18). There is a wide splint in front of the puller, which will not damage the wire. This kind of pulling tool can be bought from the supplier, and it is very useful when it needs to use a large pulling force on the wire. For fixing the silk cloth, it is best to pad two or three layers of paper (Figure 19) to prevent breakage. The paper fiber used is about 1/64 inch (0.398 mm) thick. For beginners, the practical and reliable way to fix the wire and pull is to use the floating rod frame. Three to four pull rods should be used for the wire, and the size of the pull rod is recommended to be the same as the inner frame of the frame. Hard frames or wood frames soaked in linseed oil are preferred. As the metal frame will be used for a long time, it should be treated very carefully in the final process. The wire can be nailed to the floating rod. When stretching the wire, use enough tension on the screw to make the wire tight. Be careful not to leave anything on the silk when handling the silk plate, otherwise the silk will have problems of knots, gaps or sags. If the rebound force is absorbed by the workpiece, a commercial pulling tool like that shown in Figure 12 can also be used to tighten the wire. In practice, wire stretching methods include manual, semi-automatic and full-automatic. They are easy to stretch the wire and quickly fix to the frame. After the wire is properly prepared, the film can be applied. Photographic photosensitive templates such as polyvinyl alcohol, vinyl acetate, modified plastics, commercial silk printing templates, gel templates, pressure-sensitive transfer films, direct indirect silk printing films, knife cutting films, etc. can be pasted on them. The most important step in the preparation work before making the silk plate is to ensure that the metal wire is very clean. Because the metal is not absorbent, it must be clean and free of grease, grease, regeneration liquid and fingerprints, so that the template can be pasted on the metal wire better. Most wires are coated with protective oil protective coating and traces of treatment, which must be completely removed before sticking the mold. The following methods can be used for cleaning the metal wire: (1) the metal wire can be cleaned with 5~10% glacial acetic acid solution for 5 minutes, and then all the residual liquid can be washed away with hot water; (2) Hold the wire directly through the gas flame or Bunsen lamp, and then wipe it with a cleaning brush to prepare for the film. However, be careful not to keep it on the flame for too long; (3) Any diluted corrosive agent can be used to clean the metal wire, and then wash the corrosive agent with hot water; (4) An old way to clean the wire is to insert the wire into a shelf with the same thickness as the frame, polish it with an emery cloth soaked in pumice, volatile oil or paint dilution solvent, and then wash it with hot water, and then the template can be pasted on the wire; (5) 10% alkaline solution or 20% ammonia solution can also be used to clean or degrease metal wires; (6) Special cleaning solvents purchased from suppliers can also be used. Using each of the above methods can achieve the purpose of cleaning, but pay attention to avoid leaving fingerprints on the silk after silk cleaning, that is, do not touch the silk with your hands. When storing the wire, you should also pay attention not to let anything fall on the wire to maintain its cleanliness

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