In the use of CTP printing plates, the printing volume is a common concern. The same plate is used by different customers, and the printing volume will be quite different. So, what are the factors that affect the printing volume?
According to work experience and user feedback, the general factors are as follows:
Printing volume is an important performance of plates, and different plates have suitable application ranges. As far as Kodak thermal CTP plate is concerned, AEM/EXD is a long-single non-UV positive plate (UV can only be used on the baked plate, and the printing volume is also good), SWORD ULTRA is a UV positive plate (UV can be used for the unbaked plate, and the baked plate can be printed after printing) The amount is extremely long), TNG is a newspaper industry long single negative plate.
The plate pressure is too large
In actual use, plate pressure is a factor that is easily overlooked. Generally speaking, when it comes to printing pressure, the first reaction of many printers is the printing pressure. On the contrary, they rarely have the concept and awareness of plate pressure. Therefore, it is easy to increase the printing pressure, especially the actual printing, instead of improving it from a comprehensive perspective. The thickness of the pad. However, the plate pressure is also greatly increased in this way, most of which are 5-15 wires (0.05-0.15mm) higher than the standard. It seems that this is just an increase, but this causes excessive wear on the printing plate, which is often beyond expectations, thereby greatly reducing the printing volume, and in severe cases, it will only result in less than one-third of the printing volume of the standard setting.
For sheet-fed commercial printing machines, the general standard plate pressure is expressed by the deformation of the blanket, that is, the thickness of the blanket that is compressed and reduced after pressing together. This range is generally 0.1-0.15mm for rigid cushion air cushion blankets. In between, it is better to set a low point if the Indian network is the main point, and set a slightly higher point if there are many solid spots. The problem is that many customers do not measure and control the plate pressure, and often judge based on experience. In fact, it may cause the settings to deviate from the standard, but they do not realize it. Printing machines are generally equipped with special tools that can measure and calculate plate pressure very well, such as the Heidelberg special gauge in the figure below. The publishing pressure can be measured by simple tools such as plug gauges without special tools. Through the calculation, it can be well controlled to avoid excessive plate pressure, and it can also avoid setting errors caused by unknown printing machine parameters, the actual thickness of the backing paper inconsistent with the nominal thickness, and operation errors.
too much friction
The printing plate will be subject to certain friction during the use of the printing press, and its source basically comes from the blanket and roller. In the above-mentioned plate pressing process, the pad setting that deviates from the standard will make the linear speed difference between the printing plate and the blanket larger, resulting in additional friction and damage to the plate. Similarly, improper setting of the ink roller and water roller, such as excessive pressure against the plate, improper pressure between the rollers, or problems with the state of the roller itself, may cause additional friction on the printing plate, thereby reducing the printing volume.
Most CTP printing plates need to be developed and rinsed after exposure. The developer is generally a strongly alkaline solution. If the development intensity is too high, it will damage the coating of the printing plate. Generally, there is no problem with flushing according to the standard setting, but if the temperature of the flushing machine is too high, the time is too long, too much replenishing liquid is added, the developing brush is too hard and the pressure is too heavy, and the flushing after developing is not rinsed clean, etc. Coatings may be damaged, reducing print runs.
In the use of CTP printing plates, the printing volume is a common concern. The same plate is used by different customers, and the printing volume will be quite different. So, what are the factors that affect the printing volume? Please listen to the (part two) breakdown!