Anilox roll inspection
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As we all know, in the flexographic printing process, comprehensive and comprehensive detection of anilox rolls is very important for improving the productivity of enterprises, and it is also very necessary. However, there are still many people in the industry who have not started to work. why? what is the reason? The most common reason to hear is "I don't know how to do it."
This article aims to teach you how to start from the beginning, tells the conditions, content and how to better detect the anilox roller, so that the company can really improve quality and reduce consumption, improve production efficiency and enhance competitiveness.
Anilox roll inspection
The purpose of running a business and opening a factory is to make a profit. Because the resources available are very limited, the company produces and processes the products to meet the requirements of customers, but also to make them profitable. In order to maintain a sustainable competitive advantage, companies are always trying every means to improve production efficiency, reduce production time, reduce production costs, reduce losses, improve product quality, reduce the number of replacement of anilox rolls, extend the life of anilox rolls, and improve Product consistency, repeatability, and predictability. But where should we start? After systematically evaluating all the links and factors in the flexographic printing production process, it will be found that the anilox roller is the key and core component in the flexographic printing process. It should be improved from the tracking test of the anilox roller to improve the whole process. The level and quality of the production process.
So, what is the detection of the anilox roller? Generally speaking, technical experts use expensive and sophisticated instruments to quickly and easily determine the volume, structural condition, and number of screens (the number of ink holes in the unit length direction of the anilox roll surface) of the anilox roller. After the measurement, a report will be obtained, which sometimes contains an image micrograph or a color digital perspective of the ink hole profile.
It is very useful to know the current volume of the inked hole on the anilox roller, so you will know if the anilox roller is worn or damaged. However, what we need is not limited to these, we also need to know the specific location of the damage and how to better prevent this damage. Since the focus of the problem is all concentrated on the anilox roll, the general inspection is impossible to find out the specific damage location, and it is impossible to improve the quality of the print while reducing the production cost. Therefore, there is a question worthy of attention here: "What information should I learn from the detection of the anilox roller?"
Start
The detection of the anilox roller is not only to check the condition of the anilox roller itself, but also to conduct a comprehensive inspection of the storage, cleaning, handling and operating conditions of the anilox roller. In addition to being able to reduce and prevent the drawbacks of the production process, it also provides a detailed operating catalogue, which is very beneficial to improve the production process. The common mistake that people make is to ask the outside helper (the technical expert from the manufacturer of the anilox roll) to check the anilox roller and check the anilox roller only in isolation. In fact, the detection of anilox rolls is an important part of improving product quality and process level. Obviously, it is impossible to call the technicians of the factory to check the factory in person every week. In fact, as long as the correct training for the printing operators, you are required to start from the anilox roller, you can continue to improve the level of technology. After training, the press operator can and should perform the monitoring of the performance status of the anilox roll as a daily task.
Necessary conditions for testing
1. Fixed inspection site. There should be a stable table or bench that is highly versatile and easy to handle, and is best placed next to the wash tank.
2. A pair of saddle roll pads for supporting the anilox roll. The roller pad keeps the anilox roller at a constant distance from the table top or the chair. The bearing can rotate the anilox roller so that the surface of the anilox roller can be detected safely and thoroughly. It is also possible to use a wooden block with a groove on the top as a roll pad. If it is better to fix the roller pad to a wider base, it can prevent accidental tilting and tipping.
3. Good observation light source. The light source is an indispensable condition for the detection of the anilox roller. Generally, the light source is placed at a position overlooking the anilox roller and is easy to adjust. In most workshops, a fluorescent tube is placed directly above the observation area. In principle, the light in the observation area should be comfortable and easy to inspect the printed proofs.
Other necessary tools include a gear removal tool, a 100x magnifying glass, a tape measure, a sticker (to indicate the damaged area on the anilox roll), and a spring blade (to remove dry residue from the side of the anilox roll). In addition, an irregular file (the burrs in the ink holes) is required. If the anilox roll is threaded, buy a threaded file.
In addition, a coded rubber stamp and rubber tweezers are required to distinguish the anilox roller from the other rollers adjacent to it. Most anilox rolls have been marked by the manufacturer with a digital series at the factory. However, after the surface of the anilox roll has been subjected to multiple surface treatments, the roll may end up being a pile of expired, useless information. If the press has a side scraper, the side of the anilox roll may wear out over time, and the serial number and the anilox roll's cable information will disappear. After every period of time, the series number and network cable of the anilox roller
The number is re-marked once, so that the information is clearly legible.
Finally, it is worth mentioning that it is also very important to do the log. Record the serial number and the number of screens of each anilox roll with a notebook. The damage of the anilox roller or any visible pattern on the surface should be recorded in the log. , including the specific location of the damage and the maintenance measures taken. In the future, when we need to resurface the anilox roll, or if we want to know the condition of each anilox roll, it is very convenient to use the log. If a similar damage is recorded on two or more rolls, it should be marked with a red mark indicating that the issue is worth investigating.
Optional instrument
At this point, you will definitely ask: "There is no mention of the equipment used to check the ink holes." Frankly speaking, you don't need these devices at all. If you want to relate the print to the condition of the anilox roll, you don't have to have a microscope worth $10,000 or an interferometer worth $60,000. It is not necessary to resort to these devices. These devices are ideal for laboratory applications, and in the pressroom, errors in the readings of the instrument may occur due to vibrations, dust, changes in temperature and humidity, and operator error. In addition, improper operation can easily adversely affect the performance of these sophisticated measuring instruments.
If the anilox roll is clean, the dot opening, depth, and thickness of the wall can be accurately measured using a dot detector or interferometer. Conversely, if the ink orifice is clogged with ink, the anilox roller will be in a state of ambiguity, which is often reflected in the ink color of the print. One of the reasons for the ambiguity is that the path of light reflected from the surface of the translucent resin occupies at least part of the volume of the inked hole. These resins contain a large amount of pigment, which is sufficient to produce a faint color on the surface of the anilox roll, and the color of the surface of the anilox roll can be observed by the naked eye without any tools.
Ok, now you know that the ink hole on the anilox roll is blocked. What other information can you observe with a microscope or an interferometer? Generally not. The dot detector is an optical measuring instrument. The dried ink resin can cause ambiguity in the ink hole, so that the technician can not clearly focus. When the ink hole is blocked, when the magnifying glass is used, the ink hole is observed. The bottom will be blurred. Since the focus cannot be clearly and accurately, it is impossible to accurately measure the depth of the ink hole. When measured with an interferometer, an interference image is produced as the amount of light reflected from the surface of the ink hole changes. This method is sometimes referred to as "echotopography." The ambiguity of the ink resin disperses the light and causes the instrument to produce erroneous readings. For example, when measuring the thickness of a mesh wall, if the reading obtained is "0", it is doubtful, because if there is no mesh wall to separate the ink holes, then the number of mesh lines of the anilox roller must also be determined. It is 0. Another example is measuring the number of screen lines of the anilox roller. If the reading is 715 before cleaning and 682 after cleaning, this also indicates a problem. Since cleaning does not change the number of ink holes on the surface of the anilox roll, it is simply that the instrument cannot interpret the received data.
The safest and most reliable way is to use a densitometer to measure density values in the field, halftones, and highlights. A densitometer is an optical measuring instrument that measures the ink transfer performance of an ink orifice by a logarithmic operation. The ink transfer performance of the ink hole is not directly related to the amount of ink. The amount of ink transferred is affected by the flow properties of the ink, such as the pH value of the ink, the viscosity, and the size of the pigment particles. In addition, it is also affected by the ambient temperature and The effect of humidity. In the printing process, as these factors change, even if the performance of the ink hole remains unchanged, the amount of ink transferred changes.
This is not to say that the measuring instrument does not play much of a role in the detection. This simply means that if you want to check if the anilox roller should be cleaned, it is generally not necessary to resort to these instruments. If the anilox roll looks dirty, it means cleaning is required; if the anilox roll looks clean, it is generally clean and does not require cleaning.