Precautions for the three common problems of the h

Precautions for three common problems in silk printing continued

second, repeatedly tightening the silk

off press printing and the use of stretchable silk can also reduce the accumulation of ink on the silk. At the same time, stretchable silk also has a more serious impact on the print quality

all silk fibers are elastic and will change with pressure and time, and the degree of change varies greatly with different materials. For example, the coarse hole wire of 110 wire can be pulled tighter than the fine wire of 305 wire, so it is not easy to deform under heavy pressure

the tension of new silk fiber will lose 25% in a few hours after tightening, which may not be printed on the machine. When printing, the silk is subjected to the downward force again and again under the action of the doctor blade, which deforms the fiber, and we will feel it soften

the best method is to tighten the wire four times within 24 hours before coating the wire. Every time you tighten, you will find that the speed of silk fiber losing tension is slowing down. Until the beginning of printing, the silk tension has been lost very little

if there is a drawing equipment in the enterprise, the silk should be placed on the equipment to make it always under the action of tension, even if this silk may have to wait for many days to print. The longer the wire is under tension, the greater the possibility of tightening the wire on the frame

it is easy to reach a higher tension by re tightening the silk after printing. Such repetition will reduce the loss of tension and slow down. Sometimes you will find that an old silk that has been used many times is even better than a new one

hard frames, such as those made of wood, do not have the advantage of repeatedly tightening wires. Excessive tension will cause wood deformation. Deformed silk is harmful, such as inaccurate overprint and uneven ink accumulation

some enterprises retain a large number of old wooden frames, thinking that this is a fortune, but they do not realize that this will cause a great burden. If the enterprise does not intend to purchase some frames that can be tightened repeatedly, it should consider replacing all the old wooden frames with new wooden frames, otherwise the quality and profit of the products will not be guaranteed. It is applicable to automotive oil pipes, brake pipes, fuel and gas transmission pipes

printing faults that may be caused by insufficient tension are:

inaccurate silk overprint

ink accumulation under the silk

feathering of printed images

inaccurate overprint of printed matter

uneven thickness of ink layer

in order to solve the problem of insufficient tension, the operator may reduce the printing speed, resulting in lower production efficiency and higher costs

insufficient tension will also cause the unsteadiness of the doctor blade when scraping, which will damage the emulsion layer and form some pinholes on the printed matter. The original function of the emulsion layer is to determine where not to ink and where to ink

old silk that has been shelved for a long time is more likely to produce pinholes. In order to repair pinholes, the production efficiency is greatly reduced, and the product quality has problems, and then the customer may reject the goods, resulting in serious losses. It goes without saying that we should be light and light

third, control the angle and speed of the doctor blade

if the product is insufficient, the most commonly used method is to increase the pressure on the doctor blade and print the same image twice. Here we suggest that you reduce the angle between the doctor blade and the substrate to less than 45 degrees, and you can get good results by printing only once. This can not only save half of the work, but also double the working efficiency with the mechanical limit piston stroke protection device in 1.4, without the registration problem caused by insufficient tension

why not directly increase the pressure of the doctor blade? This is mainly because the ink runs directly down through the graphic area of the silk. Compared with 30 degrees, there will be more at 60 degrees 1 Specification a. the machine allows the ink with a maximum load of 10 tons to be carried by the blade of the doctor blade, and the downward trajectory of the ink is offset, resulting in a thick ink accumulation

the ink is pushed forward by the doctor blade and scraped flat on the wire. The pressure of the doctor blade is achieved at the moment when the silk fiber contacts the substrate. At this time, the ink with different viscosity contacts the substrate in the graphic area. Any doctor blade pressure that exceeds this critical value will cause ink accumulation, damage silk fibers, and damage the emulsion layer

the ideal angle between the doctor blade and the substrate is 45 degrees. Greater than 45 degrees, the amount of ink pushed by the doctor blade is less, and vice versa

in addition, the speed of the doctor blade also affects the amount of ink accumulation. Push the doctor blade at a faster speed, and the amount of ink accumulation is small, because the force applied to the running direction of the doctor blade is greater than the force applied to the substrate. Reducing the angle of the doctor blade without slowing down the speed of the doctor blade will not reduce the production efficiency

the advantage of printing with automatic equipment rather than manual equipment lies in the doctor blade. 4. If the operating mechanism is found to be ineffective, the angle and speed. When printing with manual equipment, the doctor blade is pushed artificially to simulate the operation process of automatic equipment

sometimes the operator exerts relatively large pressure on the doctor blade at the beginning, and then relaxes the pressure on it when moving the doctor blade; Sometimes it is light and then heavy; Sometimes it's important. This change of angle and pressure should be strictly avoided, otherwise it will cause instability of printing quality

IV. conclusion

if you visit a mature automatic silk printing operation, you will find that the ink is very thin, like water, which is very different from the original ink just bought back. Feel the tension of the silk again. Almost no ink accumulates under the silk. The printing quality is very good, and the touch is very soft, and the production speed is also relatively high. It's all worth learning how to prepare ink, understand the influence of wire tension on quality, and how to choose the appropriate angle and speed of the doctor blade, which creates favorable conditions for improving the profit margin of the enterprise

if we grasp the scale of these three areas, the product quality, production efficiency and reputation of the enterprise will be improved, and the cost will be effectively controlled