One of the errors:
Plate selection is blind
Many platemaking companies do not consider the actual situation of the printing factory, such as the type of printing machine, the thickness of the sticker tape, the type of ink used, etc., and blindly follow the public. Taking the printing plate used for corrugated boxes as an example, many customers only know about the famous TDR plate of DuPont. TDR is a widely used corrugated paper printing plate with excellent plate-making performance, but its resolution is not as high as that of a series of thin plates such as EXL/UXL. When printing E-type corrugated and up to 120 lines/inch images, thin plates such as EXL/UXL should be used instead, and sponge pads should be used so that high resolution can be achieved. At the same time, with the increase in the hardness of the plate, it is also possible to reduce dot gains and achieve excellent results.
Misunderstandings:
Pre-press system configuration is unreasonable
Because the special software for flexo printing is relatively expensive, non-average small and medium-sized plate-making companies can afford it. Therefore, only a handful of overseas companies can afford it at present, while the vast majority of plate-making companies have made localized measures according to local conditions. In general, small-scale plate-making factories mostly use platform scanners and digital cameras as input devices, modify PCs or Apple G3s used in computers, and include imagesetters and punchers as output devices. Due to the limitation of the platemaking scale, many domestic manufacturers copied the configuration of the offset printing plate and even adopted the lagging technology such as the print output and the camera, which made the domestic corrugated carton flexo printing technology always at a low level, just as a hand carved rubber plate. The alternatives have not entered the era of color corrugated box printing. Compared with foreign counterparts, we have been behind for nearly 10-15 years.
Misunderstandings:
Use offset film as final output film
Admittedly, offset printing films have a series of advantages such as convenient purchase, economy, and timely delivery, and the process conditions are relatively mature. However, the offset film has a fatal weakness: the surface is too smooth.
The photosensitive resin flexographic plate will release a certain amount of oxygen during the photopolymerization reaction (the physicochemical mechanism is patented and will not be disclosed). Only the matte film can smoothly guide the oxygen out, so that the film and the plate are still maintained. Should contact, accurately transfer the image. On the contrary, the surface of the offset printing film is smooth and smooth, and oxygen cannot be smoothly exported, resulting in a large gap between the printing film and the printing medium, causing image deformation, thicker graphics, and blurring. Some plate-making operators used the method of spraying powder to alleviate these problems to a certain extent, but at the same time it also led to a decrease in light transmittance and an increase in the film's haze.
Misunderstandings:
Platemaker design flawed
Some domestic plate-making machine manufacturers, in order to compete on price, shoddy at low prices. The typical practice is to copy the circuit design of fluorescent lamps and adopt low-price domestic ordinary UV lamps. Since the fluorescent lamp circuit is started directly by the starter, the flicker generated after starting the lamp will inevitably result in uneven back exposure of the plate such as EXL/TDR, which requires a high back exposure and a short back exposure time. This results in a base material. Uneven photosensitivity, such plates will have a wavy base after washing.
The correct approach is to use high-quality UV light sources. For example, PH ILIPS' VA-R series lamps are equipped with high-quality ballasts and starters, and a filament voltage of about 5 volts is applied at both ends of the filament (very important). In this way, the filament can be kept in a red hot state. When the light is exposed, only the main circuit power supply needs to be connected, and the lamp can be started instantaneously and the exposure is even.
The PHILIPS lamp with this connection can radiate more than 160mW/cm2, while the ordinary lamp only has 40mw/cm2. The radiant energy differs by a factor of 4, which means that the same exposure amount The difference in efficiency is 4 times.
Misunderstanding 5:
Misunderstanding exposure latitude
According to the accepted standards of the international FTA, the exposure latitude is defined as follows:
Latitude = cut-off time - forming time
1. For corrugated-card printing plates (2.84mm or more), it means that the depth of the 0.8mm-wide Yinxian line has decreased to 0 from the exposure time formed on the 34L/cm plate from the 3% dot. Lmm time only.
2 For thin plates (below 2.84 mm), the depth of the catenary line up to 0.8 mm wide is reduced to 0 from the exposure time formed on the 48 L/cm plate from 2% dots. When lmm deep stops.
The greater the degree of latitude, the less sensitive the change in the exposure time of the media. Prior to the formation of dots in some inferior media, the Yinxian has been filled, and its exposure latitude is negative, that is, the dot and Yinxian effects cannot be printed on the same plate at the same time.
Some plate makers have excessively demanded the depth of the plate relief, making the substrate too thin, making the main exposure time long and losing the depth of the Yinxian.
Misunderstanding 6:
Do not pay attention to keeping the plate making solvent fresh
Each wash plate should be replenished with an appropriate amount of fresh wash solvent to keep the photosensitive resin components in the solvent from being too much.
Never use old, undistilled solvents as a fresh solvent in the piping of fresh solvents. Otherwise, it seems that the cost is saved, but considering the downtime and waste of paper due to the problem of printing plates and speeding up the damage to the platesetter, it is actually not worth the candle. Once there was such an example, the value of more than 10 million US dollars plate-making machine, due to long-term supply of fresh solvent is not enough, resulting in agglomerated brush, spray clogging, the machine is not well cycled and many other failures, almost caused the plate-making machine scrapped, forced to please To the original French engineer to repair, only to avoid more losses.
Therefore, ensuring a certain amount of fresh solvent supply can not only reduce the stickiness and swell of the plate, but also increase the speed of plate washing. It also helps to prolong the life of the plate cleaner and improve the quality of the plates.
Plate selection is blind
Many platemaking companies do not consider the actual situation of the printing factory, such as the type of printing machine, the thickness of the sticker tape, the type of ink used, etc., and blindly follow the public. Taking the printing plate used for corrugated boxes as an example, many customers only know about the famous TDR plate of DuPont. TDR is a widely used corrugated paper printing plate with excellent plate-making performance, but its resolution is not as high as that of a series of thin plates such as EXL/UXL. When printing E-type corrugated and up to 120 lines/inch images, thin plates such as EXL/UXL should be used instead, and sponge pads should be used so that high resolution can be achieved. At the same time, with the increase in the hardness of the plate, it is also possible to reduce dot gains and achieve excellent results.
Misunderstandings:
Pre-press system configuration is unreasonable
Because the special software for flexo printing is relatively expensive, non-average small and medium-sized plate-making companies can afford it. Therefore, only a handful of overseas companies can afford it at present, while the vast majority of plate-making companies have made localized measures according to local conditions. In general, small-scale plate-making factories mostly use platform scanners and digital cameras as input devices, modify PCs or Apple G3s used in computers, and include imagesetters and punchers as output devices. Due to the limitation of the platemaking scale, many domestic manufacturers copied the configuration of the offset printing plate and even adopted the lagging technology such as the print output and the camera, which made the domestic corrugated carton flexo printing technology always at a low level, just as a hand carved rubber plate. The alternatives have not entered the era of color corrugated box printing. Compared with foreign counterparts, we have been behind for nearly 10-15 years.
Misunderstandings:
Use offset film as final output film
Admittedly, offset printing films have a series of advantages such as convenient purchase, economy, and timely delivery, and the process conditions are relatively mature. However, the offset film has a fatal weakness: the surface is too smooth.
The photosensitive resin flexographic plate will release a certain amount of oxygen during the photopolymerization reaction (the physicochemical mechanism is patented and will not be disclosed). Only the matte film can smoothly guide the oxygen out, so that the film and the plate are still maintained. Should contact, accurately transfer the image. On the contrary, the surface of the offset printing film is smooth and smooth, and oxygen cannot be smoothly exported, resulting in a large gap between the printing film and the printing medium, causing image deformation, thicker graphics, and blurring. Some plate-making operators used the method of spraying powder to alleviate these problems to a certain extent, but at the same time it also led to a decrease in light transmittance and an increase in the film's haze.
Misunderstandings:
Platemaker design flawed
Some domestic plate-making machine manufacturers, in order to compete on price, shoddy at low prices. The typical practice is to copy the circuit design of fluorescent lamps and adopt low-price domestic ordinary UV lamps. Since the fluorescent lamp circuit is started directly by the starter, the flicker generated after starting the lamp will inevitably result in uneven back exposure of the plate such as EXL/TDR, which requires a high back exposure and a short back exposure time. This results in a base material. Uneven photosensitivity, such plates will have a wavy base after washing.
The correct approach is to use high-quality UV light sources. For example, PH ILIPS' VA-R series lamps are equipped with high-quality ballasts and starters, and a filament voltage of about 5 volts is applied at both ends of the filament (very important). In this way, the filament can be kept in a red hot state. When the light is exposed, only the main circuit power supply needs to be connected, and the lamp can be started instantaneously and the exposure is even.
The PHILIPS lamp with this connection can radiate more than 160mW/cm2, while the ordinary lamp only has 40mw/cm2. The radiant energy differs by a factor of 4, which means that the same exposure amount The difference in efficiency is 4 times.
Misunderstanding 5:
Misunderstanding exposure latitude
According to the accepted standards of the international FTA, the exposure latitude is defined as follows:
Latitude = cut-off time - forming time
1. For corrugated-card printing plates (2.84mm or more), it means that the depth of the 0.8mm-wide Yinxian line has decreased to 0 from the exposure time formed on the 34L/cm plate from the 3% dot. Lmm time only.
2 For thin plates (below 2.84 mm), the depth of the catenary line up to 0.8 mm wide is reduced to 0 from the exposure time formed on the 48 L/cm plate from 2% dots. When lmm deep stops.
The greater the degree of latitude, the less sensitive the change in the exposure time of the media. Prior to the formation of dots in some inferior media, the Yinxian has been filled, and its exposure latitude is negative, that is, the dot and Yinxian effects cannot be printed on the same plate at the same time.
Some plate makers have excessively demanded the depth of the plate relief, making the substrate too thin, making the main exposure time long and losing the depth of the Yinxian.
Misunderstanding 6:
Do not pay attention to keeping the plate making solvent fresh
Each wash plate should be replenished with an appropriate amount of fresh wash solvent to keep the photosensitive resin components in the solvent from being too much.
Never use old, undistilled solvents as a fresh solvent in the piping of fresh solvents. Otherwise, it seems that the cost is saved, but considering the downtime and waste of paper due to the problem of printing plates and speeding up the damage to the platesetter, it is actually not worth the candle. Once there was such an example, the value of more than 10 million US dollars plate-making machine, due to long-term supply of fresh solvent is not enough, resulting in agglomerated brush, spray clogging, the machine is not well cycled and many other failures, almost caused the plate-making machine scrapped, forced to please To the original French engineer to repair, only to avoid more losses.
Therefore, ensuring a certain amount of fresh solvent supply can not only reduce the stickiness and swell of the plate, but also increase the speed of plate washing. It also helps to prolong the life of the plate cleaner and improve the quality of the plates.
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