Digital printing machine maintenance method
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With the advent of the Internet era, personalized and customized products are increasingly expected. The continuous innovation of digital printing equipment has attracted the attention of many investors. Maintaining the maintenance of digital presses is especially important for controlling the quality of digital prints. To this end, as a practitioner who has been in contact with digital printing for many years, the author uses the HP Indigo 5500 digital printing machine currently used by our company as an example to share with you some experience and experience in maintaining digital printing equipment.
Environmental temperature and humidity control is the premise
When it comes to the maintenance of digital printing presses, the author believes that the temperature and humidity should be controlled first. This is the prerequisite for the good use of any equipment and the guarantee for the normal operation of the equipment.
1. Control of equipment environment temperature and humidity
The HP Indigo 5500 digital press is extremely environmentally demanding and can be divided into two areas. First, the requirements for the environment of the equipment, the temperature should be controlled to 23 ~ 27 ° C, the humidity should be controlled to 40% ~ 60%, and maintain the cleanliness of the production environment. Our company has set up a separate operating room for the HP Indigo 5500 digital press, equipped with special air conditioning, dehumidification and humidification systems, ventilation devices to reduce personnel access and close the door.
Second, some core working areas inside the equipment require a certain temperature or humidity to reach a certain standard in order to achieve the best working condition. The HP Indigo 5500 digital press provides temperature detection points for two internal core work areas, an electronic ink reservoir and a PIP photographic imaging plate. The temperature requirements of these two areas are strictly controlled, and once the temperature is not met, it will affect the flow and transfer effect of the electronic ink. Therefore, the device system determines that when the two temperature control detection points fail to meet the standard requirements, the device cannot work normally. Generally speaking, equipment with high requirements on the temperature of the core work area will have its own temperature control system, but it is not excluded that some equipments do not have their own temperature control system in order to reduce the cost. This puts higher demands on the control of the ambient temperature of the equipment. Printing companies need to pay special attention to this when purchasing equipment.
2. Control of the storage environment of raw and auxiliary materials
It is worth noting that the control of the storage environment of raw and auxiliary materials is as important as the control of the temperature and humidity of the equipment environment. I often see some companies put the digital printing machine in a bright, spacious, constant temperature and humidity environment. The surface of the equipment is spotless and clean. The warehouse where the paper is stored has no temperature and humidity control facilities except for the lighting. The company even piled paper in the aisle or corner of the room. The author does not advocate this practice very much. The storage environment of raw and auxiliary materials is somewhat more important than the environment in which the equipment is located. In particular, humidity has a great influence on paper. Humidity is too high, paper will become soft due to increased water content; humidity is too low, paper is prone to static electricity, and paper jam is easily caused during printing. If the humidity changes frequently, the paper is prone to bending and deformation, which directly affects the quality and appearance of the printed matter. I recommend that if the paper is not used immediately during the specific operation, try not to open the outer packaging. If the paper is not used after the outer packaging is removed and needs to be stored for a long time, it should be returned to the warehouse as much as possible, especially for low-quantity paper and no For printing materials such as dry glue, it is especially necessary to pay attention to the control of the storage environment.
Maintenance of core components is a top priority
In addition to the control of ambient temperature and humidity, the author believes that several core components such as blankets, PIP photographic imaging boards, BID image developers, etc. are also the top priority of digital printing machine maintenance.
The HP Indigo digital press is called a "digital offset press" because it uses a blanket cylinder to indirectly transfer ink and uses only one imaging drum to complete multicolor printing. The key technology of the HP Indigo digital press is a special electronic ink consisting of image oil, concentrated ink and conductive liquid that dissolves on the substrate without heating. The digital printing system evaporates the liquid electronic ink at a high temperature of about 100 ° C by heating the blanket to form a viscous polymeric film, which is cooled and transferred to the substrate. The polymeric film is 100% transferred between the imaging drum, blanket, and substrate, with no residual ink remaining on the blanket. This way, each time the blanket is rotated, the graphic on it can be different. It can be seen that the blanket plays a key role in the perfect transfer of the graphics of the HP Indigo digital press. In normal use, the cleaning and maintenance of the blanket is the most frequent. In the following, the author will introduce the maintenance and maintenance of the blanket in detail.
1. Blanket cleaning
In daily production, the maintenance of the blanket is basically based on cleaning, and the blanket should be cleaned regularly. There are two ways to clean the blanket: automatic and manual. The automatic cleaning method requires the “Printing and Cleaning Page Wizard” function of the digital printing system, which is what we usually call the printing cleaning page. Follow the instructions of the guide. If more than 30 cleaning pages are printed, the entire residue is not completely removed. The blanket can only be cleaned manually. When cleaning the blanket manually, pay attention to the protection of the eyes and hands. The cleaning cloth should be cleaned with a dust-free cloth. It can be folded and used on multiple sides. When wiping, the action should be light and should be wiped in one direction. Otherwise, it is easy to entrain particles and dust. Injury the surface of the blanket, causing irreversible damage to the blanket. If the blanket surface is still smudged after wiping the blanket with a lint-free cloth, use a picture oil to wet the clean cloth, then wipe the blanket until the residual ink and other stains are removed (if there is no more on the dust-free cloth) Remnant ink, indicating that the blanket has been wiped clean).
In addition, it is also recommended to print 2 to 3 cleaning pages before printing products with high quality requirements, and often sample samples during the production process. Once the cleaning page is found, there are obvious bars, uneven color transition, or proofs. Missing, first consider cleaning the blanket and checking the damage of the blanket. If you find residual ink or paper dust on the blanket, be sure to remove residual ink and paper scraps before cleaning the blanket.
In addition, when the substrate jams the printing unit during the production process, it should be processed as soon as possible in order to restore the surface of the blanket in time, otherwise any improper operation may cause the blanket to be scrapped. When paper scraps are found on the surface of the blanket, remove the residue immediately when the temperature of the blanket is high. If necessary, use a dust-free cloth that is wet with the image oil to wet the edges of the paper, and remove the whole piece of paper from the eraser. Removed on the cloth. At this point, be careful not to use a dust-free cloth dampened with image oil to directly wipe the entire piece of paper. This may cause the blanket to become sticky and the blanket to be unrecoverable.
2. Blanket replacement
The blanket of the HP Indigo digital press has a certain service life. Generally, the blanket needs to be replaced once around 50,000 prints, depending on the product requirements and product type. The replaced blanket, as long as there are no obvious defects, will generally be retained, and it will be reused when printing black and white products, products with small ink, no large-area graphic, or plain text products.
After replacing the blanket, you need to correct the transfer pressure and adjust the pressure between the PIP roller and the ITM roller (rubber cylinder). Proper and balanced pressure between the two is one of the key factors in printing high quality digital prints. If the adjustment is not appropriate, there are generally several failures:
(1) The image area is not inked, and a cloud-like blank pattern appears;
(2) Bright dot or less than 10% of small dots cannot be transferred to the substrate or the transfer is poor. The correction of the transfer pressure is also available in both manual and automatic modes. When manually calibrating, it is required to print 9 test pages. The test page contains 2 columns of triangles, 6 columns each. Each column of triangles represents the two sides of the roller. Each test page has a number, and the test pages 1 to 9 correspond to The transfer pressure gradually increases. Only when the triangle of each column on the test page is complete, the corresponding transfer pressure is correct. Record the test page number and input the corresponding transfer pressure to complete the transfer pressure correction process.
In addition to the blanket, the PIP photographic imaging plate, BID image developer, etc. have a certain service life and need to be replaced periodically. However, in actual use, the actual service life of these consumables will be somewhat different from the standard service life given by the manufacturer, which is related to the daily operation and maintenance of the operator. Among them, when cleaning the inking unit regularly, pay special attention to the standard operation to prevent mechanical damage, especially when installing and removing the inking unit to prevent accidental scratching and scratching the developing roller. If cracks and scratches appear, It will directly shorten its life. In addition, when cleaning the inking unit on the cleaning table, you can pay attention to the wear of the surface of the developing roller. Generally, the wear is caused by the improper pressing time of the inking unit and the PIP photosensitive imaging board. When the wear is found, it should be notified in time. Service engineers deal with hidden dangers.
Cleaning the paper path is also very important
In the daily use of the digital printing press, it is also necessary to pay attention to the cleaning of the paper path, especially the various sensors, conveyor belts, conveyor rollers and the like for cleaning the paper path. Among them, the conveyor belt and the conveying rubber roller on the paper path are responsible for the paper conveying task. If the surface is dirty, it will be directly transferred to the paper, causing the printed matter to appear gray on the bottom surface. When cleaning the sensor, pay special attention to cleaning the parts where the photoelectric sensor installed upwards is easy to be dusted and the parts where the sensor is not easy to wipe. If these parts absorb and accumulate excessive paper and paper dust, the sensitivity will be affected, so that the detection will not be detected. To the paper position, causing an error, or the mechanical parts are not working properly, causing paper jams and other paper feed problems. In addition, while cleaning the paper path, also pay attention to check the wear of the relevant rollers, rollers, belts, find the problem parts in advance and replace them in time to reduce the occurrence of paper jam.
Digital printing equipment has many similarities to the maintenance of traditional printing equipment, but there are many differences. This requires our operators to treat them differently and to achieve comprehensive equipment maintenance and maintenance. Here, the author also hopes that the printing company can provide customers with better and more exquisite digital prints through their own efforts, let the digital printing bloom everywhere, and bloom a unique and charming fragrance.