Troubleshooting (6) - Practice solving problems
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December 23 13:11:58, 2023
It is impossible for a worker to find a solution to a particular problem in a manual. Of course, you can also write each step as described above. However, this is meaningless work. If the problem is caused by insufficient tension in the stretch net, then the tension can be increased; if the gap between the screen and the substrate is too large, the gap is reduced. However, due to various reasons, the reasons are combined with each other. If you write down all the problem solving methods, it is estimated that there are 10 dictionaries so thick. This is only to help workers find a solution to the problem in a relatively short period of time without resorting to chaos. In this section, simple or complex problems can be solved as described in the table. However, how to solve problems is more important than solving problems. We should study carefully until the logic of solving the problem becomes clear. The simple problem: on printed sheets consisting of lines and solids, the graphic-free part (background) is always covered by small, messy printed ideas. Finding the crux of the problem can remove it from the print and prevent it from reappearing. The first step is to analyze the position, size, and frequency of the ideas. You will find that the ideas always appear in the same place on the printed sheet and are of equal size. The second step to identify other problems that may be present may give you additional clues. Are there jagged edges, missing details or missing edges and certain areas? At this time, you can use the microscope to view the graphic, you will find the flash and details missing. The third step, as described in the previous procedure, looks at the problem flow chart and analyzes the most probable causes: Screen. On the whole, it is a very correct procedure. Following it, there will be very few mistakes. When you have some experience, there will be some shortcuts. Some of the factors produced more easily than others. Be cautious when deleting them from your list, even if they are all you never thought of. For example, checking the manuscript is a relatively simple step and it only takes a few minutes. If you are lucky, you may find that the manuscript is the crux of the problem and you don't have to check it. If not, you do not spend too much time, and rule out a factor. Similarly, checking the tension of the stretch net, the screen, and the gap between the substrates is also a very simple procedure, and even if they are not the most likely factor, it is worth checking. In this problem, if the original is free from blemishes, burrs, or missing details, then you must continue to analyze the cause from the screen. The fourth step is to look at the PFC table. The secondary reason is that the stretch tension is too small. If you look at the bars with jagged edges and loss of detail, you will find that stretching tension is an important cause. However, low stretch tension does not cause pinpoints. Therefore, you must find the reason that can cause these three kinds of problems at the same time, namely pinhole, burr and detail are lost. The most common reason for the fifth step can be found in the Problem Description or in the problem lookup table. The reason for this is that you have found out that the film is underexposed or the film is not acceptable. The sixth step to solve this simple problem consists of the following steps: a. Replace the new screen b. Check the quality of the film c. Check the process of making the web. If necessary, write the correct process including accurate exposure time, distance, etc. d. Write down the process of solving the problem and include a sample in the table of problem solving. Complexity: Prints are bow-tie shapes consisting of equally spaced lines. In the middle of both sides of the bow, there is a small area (about 0.25 inches in diameter) that is not printed. Check if the screen is blocked and it looks normal. You can print a few precise patterns after cleaning, but after four or five shots, the missing ideas will appear again. Solve this problem and prevent it from reappearing. The first step is to observe the position, direction, size, and frequency of the point. You will find it always appears in the same place, but it is not very accurate. There is randomness in either shape or size. However, in addition to the first few, problems always exist. The first step in the second step is to check the original. The problem is not caused by the original manuscript, but you'd better confirm it. Of course, there is no problem with the original. The third step to check if there are other issues may give you some inspiration. Observe the problematic area with a microscope and you will find that although the ink is a bit more, the image is correct, but the line near this area is a bit rough. The fourth step continues to find the cause from the PFC and the problem description. The screen you use is a standard 18N/cm screen, and the distance between the screen and the substrate is also a suitable 0.125 inch. It has been working very well so that it is not like the tension of the stretching net or the screen The reason for the distance between the substrates (although they are extremely prone to problems). However, from the problem description table you find that the missing image is related to the distance between the screen and the substrate. Step 5 When you find that you cannot find an exact reason, you should understand that you must have overlooked an important detail. At this time, you must carefully observe the process of separating the screen and the substrate. This process will let you understand how stretching tension and the distance between the screen and the substrate affect the results. The sixth step is to change the speed of printing (slower or faster) to observe the separation process. See if the ink behind the squeegee is straight and parallel to the squeegee (as is normal). If you use low speed, you will find the first clue. Observe the shape of the ink and you will find that it is not a straight line. It is actually split into two semicircles on either side of the bow, which is a secondary clue. The seventh step analyzes this. At low speed, the ink behind the squeegee is straight and there will be no image loss. At high speed, ink is a special shape, and problems arise again. The only difference is the squeegee speed unless the shape of the image is related to this issue. In general, you don't have to do more experiments with image shapes. It can be assumed initially that the shape of the image is the cause of the problem. You can't change the shape of the image, but you can look for factors that are related to it: Other factors can be changed. Before you find other factors, you can see the missing image column in the problem description table, where there are six possible causes. Based on this, you can easily conclude that for a particular shape of image, the standard stretch tension and the distance between the screen and the substrate are not appropriate. One situation is that the image is significantly divided into two parts (as in this example), and the other is that the image is too large for the screen. In both cases, the ink is not a straight line, it will form an arc at a certain point. The secondary method is to reduce the distance between the screen and the substrate or increase the pressure of the squeegee, which is conducive to screen separation. If high-viscosity inks are used, neither method will work. (Reducing the distance between the screen and the substrate may cause the separation to worsen, and increasing the pressure will bend the blade and increase the lower leakage of the ink.) The best solution is to increase the tension and reduce the tension. Reduce the distance between the screen and the substrate so that the amount of ink is ensured and the screen and the substrate are well separated. This only option will reduce ink viscosity and print speed. This method can only solve one version of the problem, but can not prevent future problems. The eighth step to solve complex problems includes the following: a. It is recommended to use two methods that are appropriate to your working condition: 1) Adjust the ink concentration (if possible) and reduce the printing speed (if necessary). 2) Use a large stretch tension and a small distance between the screen and the substrate. b. A large screen tension is applied to the special image that will be divided into two parts. c. Write down your problem solving process and save the sample for future reference. Conclusion: The following steps need to be taken to solve a particular problem: 1. Identify the characteristics of the problem from four perspectives (position, orientation, size, and frequency), if necessary, using a microscope. 2. Classify the problem and find the location of the problem in the problem description table. 3. Find relevant second evidence and determine the cause. 4. Analyze the most important factors and find the most likely cause of the problem based on the PFC or performing a local analysis on your own. 5. Find out why the assumptions are met and the results are consistent. 6. It is recommended to use a solution that completely solves the problem in accordance with the current conditions. 7. Record the steps taken to resolve the problem and leave a sample for later reference. Once you have accumulated experience, you can quickly find one or more underlying factors in the table. If you can find the root cause of the problem at once, you will save a lot of time; if not, time will not be wasted because at least one possibility is eliminated. Factors that can easily cause problems are: images, stretch tension, and gaps. In a broad sense, Troubleshooting is a linear process that solves problems step by step according to the order of A, B, and C. It can also be said to be a comprehensive method. All aspects of the problem must be understood, and only understanding what is the problem is not enough. The understanding of classification, and know that the probability of the problem is not enough. The problem must be viewed from every angle at the same time. Doing so will have a multiplier effect. Sometimes, you may not find the cause at once, as if all factors have nothing to do with the problem. You must walk around this problem until you understand it.