Over the past 10 years, printing technology has changed with each passing day, and CTP plates have also traversed a path of rapid development and continuous transformation, from the beginning of silver salt plates to later resin plates; from photosensitive technology to thermal technology; from a Technology is leading the way, and now the photosensitive, thermal, CTcP and other hundreds of contentions contend, and the market is still developing rapidly. But at the same time of rapid development, it inevitably brings irregularities in use and operation. In the process of digital printing, the standard for the inspection of plate materials is no longer as simple as ensuring that 1% to 99% of the dots are restored and the blank parts are not dirty. In order to restore more layers in the printing process and effectively control the quality of the printing, the layer adjustment is usually carried out by means of the printing dot compensation curve. An important criterion for the CTP version material inspection is to perfectly reproduce this compensation curve on the printing plate. This article will mainly introduce the adjustment of the developing equipment and the use of test control strips to evaluate and control the quality of the plate. Adjustment of developing equipment At present, most of the thermal CTP plates used by domestic printing companies require chemical treatment (that is, development), and the quality of the plates is evaluated after development. The first introduction to the adjustment of the developing machine is mainly to show that the area of ​​the digital measurement and control strip is very small. The premise of reflecting the entire layout through this part is that the developing machine develops uniformly. Only under this premise, the evaluation of the parameters of the digital measurement and control strip is meaningful. In theory, the unexposed glue layer is insoluble in the developer. However, in the development process, even the squeezing friction of the driving roller against the plate surface and the flushing action of the developing brush, even the unexposed glue layer will produce a certain degree of dissolution. To stabilize the printing dot compensation curve for a long time, it is necessary for the developing machine to have a more stable solubility of the adhesive layer. The film retention rate is generally used to describe and monitor this property of the developing machine, and the change of the film retention rate will directly affect the dot area ratio. 1. Determination of film retention The film retention rate is calculated by measuring the solid density of the plate before and after development, and is an important indicator to judge the development effect. Film retention rate = (before D / after D) × 100% In the formula, D before represents the solid density of the plate without exposure, and D after represents the solid density of the plate after development. Under the premise of ensuring the blank part is clean, the higher the film retention rate, the better. The pattern plate needs to ensure that the film retention rate is ≥90%. Use X-Rite500 series X-Rite500 spectrodensitometer, C channel (without optical filter) to measure the D front and back of the plate. The cleanliness of the blank part plays a decisive role in the hydrophilicity and dirtyness of the printing process. For the detection of the blank part of CTP plate material, the blank part can be modified by a revision pen. Compare the contrast between the modified and unmodified areas. If the contrast between the two is extremely small, the blank part is clean. 2. Factors affecting the rate of film retention (1) Development temperature. The influence of this attribute on the film retention rate is the highest. The uniformity of the temperature in the entire developing tank needs to be measured at multiple points with a thermometer, and the difference is preferably controlled within ± 0.3 ℃. If the difference is large, check whether the heating, cooling and circulation systems are working properly. (2) Development time. This attribute has a smaller effect on the film retention rate than the development temperature, but also pay attention to the uniformity. In each stage of development, the plate will be affected by one or more sets of rubber rollers. If these forces are too different, the speed of the plate through the developing machine cannot be uniform, and the development time will be uneven. (3) Developing brush pressure. Pay attention to the size and uniformity of the brush pressure during the development process. Excessive pressure may cause problems such as scratching of the adhesive layer and low film retention rate. Too low a pressure will cause incomplete development and dirty printing; uneven pressure and uneven development. (4) The dissolving power of the developer to the glue layer. Due to the consumption and self-oxidation during development, the dissolving power of the developer is not constant throughout the life cycle. The amount of dynamic replenishment and static replenishment must be reasonably set to balance the solubility throughout the life cycle. It can be set according to the manufacturer's recommended value, but it is necessary to measure whether the amount of replenishment is consistent with the set value, and adjust the replenishment in conjunction with the measurement of the film retention rate. [next] Measurement and control strip evaluation Various thermal CTP equipment and supporting processes on the market are basically equipped with a measurement and control strip for controlling the output quality of the plate. This measurement and control strip is extremely important for the detection of plate-making. It contains a wealth of information on plate-making and development. The following is a detailed description of the three common measurement and control strips. 1. Kodak measurement and control strip (1) Small outlets. This unit consists of 98%, 2% and 99%, 1% of 175Lpi dots. Its function is to detect whether the plate can output small dots completely. In general, normal quality CTP plates can easily reproduce small dots on Kodak equipment. (2) Pixels. This unit detects exposure, development and even focusing. The upper part is 50% of pixels from (1 × 1) to (4 × 4) pixels. The lower half is a 50% square dot of 175Lpi. Under normal circumstances, the (1 × 1) pixel can be distinguished by a magnifying glass, and the color of the (3 × 3) pixel is basically the same as the color of the following 50% dot, which is qualified. (3) The tone of the outlet. This unit is used to evaluate the reproduction of dots on the output plate. The dots in the upper half are adjusted through the dot compensation curve. In the upper part of the inspection, you can compare the actual curve and verify whether the output dots meet the printing control requirements. The lower half is not affected by the dot compensation curve, and the measured dot area ratio should be equal to the marked value. When the exposure and development are insufficient, the dots tend to appear larger, and vice versa. Examining the lower half, you can check the dot reproduction ability and accuracy of the plate. A stable plate should have a small dot reproduction error. (4) Thin pixel lines. The thin pixel lines mainly serve to check the laser focusing. When the focus is correct, the thin lines of each pixel can be completely reproduced; if the focus is not correct, the thin pixel lines are likely to appear unclear and incomplete. 2. Agfa measurement and control strip (1) Exposure control area. It is divided into 6 small circles and a background. The small circle is composed of (1 × 1) ～ (6 × 6) pixels, while the background is (8 × 8) pixels. When the exposure is normal, the ring and background are basically the same. If the exposure and development are insufficient, the greater the intensity, the larger the value of the ring will turn blue, the exposure and development intensity needs to be increased, otherwise it will become white, and the exposure and development intensity needs to be reduced. (2) Fine line area. It consists of 4 parts, each part is divided into horizontal and vertical lines, and the width of the line is 1 to 4 pixels, the minimum width of the thin line is 10.6μm, the exposure can be detected from the clarity and completeness of the fine line . 3.Screen measurement and control strip (1) White domain. That is, the white dot area is used to check whether the plate can be developed completely, and can be used as the reference point for the test. Corresponds to the 100% black field on the far right. (2) Exposure inspection area. This area is completely consistent with Agfa's exposure control area. The difference is that Screen turns Agfa's ring into a rhombus. (3) Thin line area. This part is used to detect focus and magnification. The function is the same as the same functional area of ​​the first two control strips. (4) 150Lpi50% outlets. As a benchmark of 50% of the dots, you can check the dot restoration and exposure. When the screen device is underexposed, 50% of the dots increase, and when overexposed, the 50% of the dots shrink. (5) Black domain. Corresponding to the white field, it is used as a test reference point and a standard point for checking the development status. Judging from the above types of measurement and control strips, we can draw the conclusion that each type of measurement and control strip is similar in function, except that the supplier has adjusted its own characteristics for its own equipment. Combined with X-Rite X-Rite500 series spectrodensitometer and IC-PLATE dot measuring instrument to measure each part, we can get the best plate-making development parameters we need. summary In general, it is not a very complicated matter to output the printing plates that meet the requirements of printing standardization through CTP. In addition to understanding the principles of CTP plate making and the characteristics of the plate materials we use, we also need to understand the characteristics of the equipment, maintain a standard operating environment, and maintain the plate making machine and developing machine regularly, operate according to regulations, and supply according to different plate materials. The control parameters provided by the manufacturer and the information of the reference measurement and control strips are used to adjust the plate making and development, and the printing plates that meet our requirements can be easily output. New kitchen cabinets make updating your home`s style and functionality easy. And, with a variety of budget-friendly in-stock and custom cabinetry options, getting the look you love is more affordable than ever. Melamine Kitchen Cabinets,Waterproof Kitchen Cabinets,Pvc Kitchen Cabinets,Solid Wood Kitchen Cabinets HOPE IKEA , https://www.skywardrobes.com
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