Analysis of operation skills of ink scraper, the h

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Silk printing tools: analysis of operation skills of ink scraper

the final result of silk printing depends on the synthesis of the technology used, so every tool, skill, formula and operator has more or less influence on it, and even the most humble ink scraper plays an important role in silk printing brush. Whether it is manual printing or mechanical printing, doctor blade is one of the most used tools in ink transmission. There are other methods to force the ink through the silk plate besides using the doctor blade, such as vacuum pressure method or rolling method, but the doctor blade is the most commonly used tool. The doctor blade consists of several parts: a wooden board with grooves as the handle; A rubber blade is inserted into the groove of the wood board to protrude from the groove; A fixture. The most commonly used doctor blade is made of two boards. The methods of connecting the doctor blade handle and the doctor blade are also different. The handle of doctor blade is mostly made of wood, but also aluminum. The groove handle can be made of hardwood or cork, but it must be dried and free of defects. Cork (such as white pine) is used because it is not only strong enough, but also light enough to make large handles. This is because the length of the doctor blade can reach about 72 inches (183 cm), so its weight is very important. The lighter doctor blade is easy to use. The handle of the doctor blade should be in contact with the operator's hand, so the edges and corners of the handle should be round to prevent hand abrasion. Although the allergy of rubber protein forces the manufacturing raw material of this product to be changed from NR latex to NBR latex leather, the blade must be well matched with the groove of the handle. If it cannot be well matched, different color inks will dry in the gap between the blade and the groove of the handle, affecting the color of the printing ink. Some operators apply shellac on the position where the blade contacts the handle groove to prevent the ink from drying and make it easy to clean. In the large silk printing workshop where three and four colors are used for printing, different ink scrapers are used for each color, and after use, they are cleaned and kept as the same color for printing. The wooden part of the doctor blade should be sanded with sandpaper to ensure that there are no rough sand spots. Rubber can also be used to make blades, which can be polyurethane or other types, but it must have good moisture resistance, corrosion resistance and heat resistance. It must be resistant to animals, minerals, vegetable oils and fats. It should also be able to withstand the oxidation effect of the metal components contained in the ink. Rubber is not affected by benzene, alcohol, paint, enamel, silk cleaning solution and film coating solution, especially when encountering some product problems. Artificial rubber has better fire resistance and printability than natural rubber. Natural rubber has short service life, is easy to deform, and is easy to be dissolved by solution. The source of rubber raw materials is the same as that of all pigments and composites. The rubber blade has various hardness. For silk printing, the blade with hardness of 45 ~ 80 is generally used. Generally speaking, suppliers have three kinds of blades: soft, medium and hard. 45~50 hardness is an extremely soft blade, and 75~80 hardness is an extremely hard blade. The edge of the blade determines the uniformity and deposition thickness of the ink. The edge of the blade must be parallel to the printing surface. The blade should fit well in the groove or between two pieces of wood, and the current global trends include the expansion of medical care channels, the aging of the population and the increase of cost, which should be fixed with wood wool nails. The fixed wood wool nails should be four inches away. They should be cross nailed. First pass through one side of the board, and then enter the other side. The blade also brings a lot of convenience to the industry, with a thickness of about 1/4~1/2 inch (0.63~1.27 cm); The height is about 1.5-3 inches (3.8-7.6 cm). The thickness, height and length of the blade depend on the size of the handle of the doctor blade and the length of the doctor blade. Although some printers can use tools to make doctor blades by hand, it is not practical after all. The best doctor blade suitable for various purposes can be bought from silk printing suppliers and is cheap. Its price varies with the line length of the doctor blade. A good doctor blade can be purchased in various lengths, and the blade and handle can be purchased separately. The length of the doctor blade depends on the live parts to be completed and the size of the frame used. It is recommended that the doctor blade used should be 2-3 inches (5-7.6 cm) smaller than the size of the plate, but it should be able to cover the whole pattern to be printed in one stroke. In order to maintain the printing gap between the two times so that the doctor blade is not in contact with the ink and give the staff breathing time, it is necessary to insert a support rod in the middle of the doctor blade. There is also a method of inserting a support rod in the vertical direction of the doctor blade surface. The doctor blade is usually controlled by two hands. When the doctor blade only needs one hand to control, the other hand can be free to rest. Like all tools, the doctor blade also has some things to pay attention to. This is mainly to maintain the sharpness and straightness of the blade. Its sharpness and straightness can be tested with a ruler or yardstick. When the blade becomes blunt, damaged and uneven, the doctor blade needs to be treated by the staff or the silk supplier to make it sharp and straight. If the doctor blade is not sharp or straight, the ink layer of printing products will be uneven, and the workers with poor skills may sometimes think that it is the reason for the ink or silk cloth. When printing with a silk printer, the flatness of the blade of the doctor blade must be checked regularly to ensure the uniformity of the ink layer of the printed matter. The knife edge can be sharpened by using a knife sharpening fixture or a special machine. The production of fixtures is very simple, which can be made of wood. The length is 1-3 feet (0.305-0.914 meters). The friction medium of the knife sharpening fixture can use 0 sandpaper, abrasive cloth with 80~120 coarse sand, or new (or old) sandpaper. The sharpening method is to hang the doctor blade in a vertical position and pull the friction material back and forth until the blade becomes smooth. If there is a belt sander or disc sander, it will save workers a lot of work. The speed of the sander is 1000~1300 rpm. If the speed exceeds 1300 rpm, the rubber may melt, because most synthetic rubbers are thermoplastic and soften when heated. In case of this situation, a small amount of water can be added to cool it to prevent decomposition and softening. In addition, press the rubber gently so that it can be rubbed without melting. Another way to sharpen the blade is to cut off a part of the blunt blade with a knife sharper than the blade, a manual paper cutter or a mechanical paper cutter. If the blade or paper knife is wiped with a wet cloth, it is easier to cut off the rubber blade. If the blade is so damaged that it cannot be ground flat, then you have to replace it with a new one. The doctor blade must be kept clean and cleaned with detergent of cleaning wire. It is more difficult to clean the dirty doctor blade after it sticks to the ink. And the dry ink may react with various color inks after printing. The doctor blade should be stored for two hours after cleaning, so that the solution can evaporate completely. In addition, if the storage time is long, it is recommended to spray French lime powder on the blade to protect the blade. Generally, it should be hung up or placed on the tool holder during storage

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