The Mystery of Leading Technology of German SPS Full-Automatic (Fast/Precision) Screen Printing System (2)

German SPS - a 100% pure automatic screen printing system that has been used for more than half a century and the world's only (a variety of fully automatic feeding devices + all types of fully automatic sheet printing presses + all types of fully automatic drying/curing systems + automatic reclaimers Development and production companies - not only adhering to the world-renowned fine tradition of German printing press production technology, but more than fifty years ago invented the principle of a stand-by drum which has so far been able to be initially copied.

SPS is not only a screen printing system development and production company, but more importantly, he may be the industry rarely understand and understand the problems of screen printing in various industries, as well as the application of various industries and different needs to be able to completely Classes and individual customers configure, develop and produce different solutions.

To simply understand the mysteries of Germany's SPS automatic screen printing technology, we can use the car as a metaphor. If an engine plus four wheels can be called on the road, then a scraping system adds a scraper. (Glue) that can move in the frame is called screen printing machine. The number of cars can range from a few tens of thousands of yuan (the same below) to several ten million yuan. Where can we choose? Of course, different people may have different pursuits and values, but they are inseparable from workmanship, performance, configuration, security, brands, etc. However, configuration and branding are very subjective, but others are objective and measurable. And four rounds are the key to performance and safety. If this key core does not work, then it is the peach wood target, the leather electric seat... Everything is in vain, what kind of engine and wheel combination and How to walk on the road is considered to be an advanced high-performance and safe car. What is the combination of the squeegee system and the squeegee and how to move it is a high-precision, high-stability and high-stability screen printer? The following one-by-one secret:

The principle and accuracy of SPS pause drum printing technology

The principle of the so-called SPS dwelling roller screen printing technology is to use the mode of operation in the industry which is now called flat pressure circle. That is, the flat screen frame moves forward and backward while the doctor blade does not move back and forth (only moving up and down). Below the screen frame is the roller driving. The substrate and the frame move synchronously. The process and principle are as follows: When the substrate (paper, film, PVC, etc.) is in the registration process, the roller is in a standstill state so that the substrate can be completely free from any interference (such as manual, unfixed positioning gauges and (or roller swaying, etc.) immediately reaches the point-to-point high-precision alignment. After accurately aligning, the paper gripper (gripper) grasps the substrate, and the drum rotates forward at this time to start printing (squeegee Press down the screen plate to the substrate, and the frame and the roller move forward synchronously. At the same time, use the suction device inside the roller to better and evenly fix the printing material on the roller. Immediately after the printing, the blowing device inside the roller assists printing. The material is more effectively removed from the drum and smoothly delivered to the conveyor belt. After this 360-degree rotation, the drum immediately stops again and repeats the movement just once to align and print another sheet (the basket is moved backwards when the drum is stopped, The blade rises and the ink blade drops to the screen for ink return function). Because the principle of SPS pause drum technology is to make the substrate completely free from any interference in the alignment process, it combines the SPS process and other advanced technologies such as special conveyor table materials, suction conveyor belts and special material rollers, etc. SPS pause roller printing technology repeatability can reach up to 0.03mm.

About overprinting and drying technology

In addition to repeatability, silk screen register accuracy is also very important. Whether it is printing on multiple ink layers (colors) or overprinting images on existing images (such as offset printing ), overprinting is almost necessary for silk screen printing, and four or even ten colors are overprinted on most screen printing applications. The above are abound. However, overprinting is often the most difficult problem for silk screen printing. It may even be an issue that cannot be solved effectively. There are two main reasons: 1) Mesh spacing, 2) Changes in substrates.

1. Network distance: The distance between the screen and the substrate (d). The silk screen must have a mesh distance to pass the ink through the screen to the substrate for printing by the pressure of the squeegee, so it is impossible to be free of the net distance (ie, the plate presses on the substrate like an offset printing), but because of the physical phenomenon, the net The distance from the squeegee under printing will cause deformation of the mesh yarn. The farther away from the centerline of the screen is, the larger the deformation is, and the larger the mesh distance is, the larger the deformation is, and the deformation of the mesh yarn represents the deformation of the image. Deformation means that it is impossible to set the standard. For example, if a 1x1 m screen prints an image of about 0.8x0.8m, you will find that both the front and rear of the printed image are larger than the original image. If your image is overprinted on an offset print such as a poster, With packaging, book editions and credit cards, you will find that it is impossible to have acceptable overprints. If the printed image is a patchwork, ie if you are arranging many trademarks, credit cards, etc., then the deformation phenomenon is more visible:

Solution:

1) Print only in the center position: This means that only 1 square meter of the pattern is printed on the center of the 1x1 meter frame. However, this method represents endless waste of consumables and low production capacity, which greatly increases costs (because equipment and manpower need to be increased) Repeat the vicious cycle described at the beginning of this article).

2) Decrease the network spacing: For technical reasons, the average network spacing of equipment in the market varies from about 4 mm to more than 10 mm, which is enough to cause serious overprint problems. SPS understands that it is not possible to exchange production capacity and operating costs. Therefore, advanced and unique flattening drums are used (the top roller holder is flat, so that it is hidden within the circumference of the drum). The standard setting of the net pitch is only 1.5 mm. It can even be set to 0 mm technically.

In addition to accurate computer calculations, it is necessary to create flattened cylinders with strict requirements for the arts to ensure that the rollers and printing presses are not affected at all in the high-speed rotation and pause. Therefore, SPS is currently the only system that can guarantee perfect overprinting without paying any price for production, quality and operating costs.

2. Change of Substrate: To ensure the best stability of the substrate during the entire multicolor overprint printing process, three factors must be clear: 1) the quality of the substrate; 2) the working environment of the printing room includes humidity and temperature; 3) Drying equipment technology. Since 1) and 2) are not the focus of this article and are generally controllable under normal circumstances, they are not described in detail here. Substrate will mainly change due to temperature and time, especially for some consumables such as film, the sensitivity will be higher. Therefore, the drying equipment is not only able to dry the ink or not is the key to affect the stability of the substrate. Simply put, the higher the temperature, the longer the drying time, and/or the greater the temperature difference (drier and room temperature), the worse the stability. That is to say, the drying machine we choose must be dry in the shortest time, the highest efficiency and the lowest temperature difference is the best, otherwise the catastrophe and losses caused by overprint problems include re-doing non-printing can Described. To achieve the above requirements, SPS skillfully applies the technology of energy transfer to the drying system and utilizes the turbo-jet hot air technology, that is, a well-designed and precise layout of the computer in a drying system. The nozzles for gas flow and gas volume calculation use the turbine to move the set temperature hot air instantaneously to evaporate the solvent and more importantly, to take away from the workshop to achieve complete drying and reduce disturbing odors. The high efficiency can greatly shorten the drying. Time and distance to reduce the risk of instability of the substrate. After drying, they pass through two stages of cooling respectively. The first section is the passageway to allow the thermal energy to volatilize and drop. The second section is still the 1000-jet-type cold air zone. The specially designed nozzle is also used to shoot 15-17 degrees cold air to make the surface of the substrate. The rapid temperature drop to near room temperature can not only reduce the impact of low temperature difference on the stability of the substrate, but can also instantly stack, use or overprint. SPS turbo-jet hot air technology uses two-stage hot air and cooling as an example. The average drying time is only about ten seconds or so (depending on the ink).