Large-format silk screen selection and tightening technology

This article will show you how to select the frame for oversized jobs and how to properly select, tighten, coat, and expose large format screens for optimal results in printing.

Browse some commercial print magazines or visit an industry exhibition and trade fair. You will find that large-format screen printing technology is being challenged by inkjet printing systems. As we all know, digital imaging technology is developing rapidly, can use long-lasting and long-lasting ink to print on a variety of substrates, and is gradually eroding the unique printing method of screen printing. In spite of this, screen printing is still occupying a strong competitive position in the field of decoration by virtue of its advancement in printing materials and the innovativeness of screen-making technology.

Screen printing is a flexible and versatile fashion for decorative printing. It is also the best and may be the only choice for some applications. Large-format screen printing is particularly suitable for medium- to large-scale production of display pictures, fabrics, decorative glass and other industrial and special-purpose products. Screen printing dominates these markets primarily because large format screen printing output speeds range from about 6,000 to 30,000 square feet per hour, while most ink jet printers produce only 100 to 2,000 square feet per hour. Another reason why screen printing is so competitive is that it has printed conductive properties, abrasion resistance, and the ability to adapt to other particles and specialty inks. Not only that, but it also has a rich ink color, including the Pantone Matching System (Pantone Matching System) corresponding color, fluorescent color, metallic color and special color ink specially configured in some manufacturers.

If we want to produce high-quality large-format images efficiently and in batches with screen printing, we must first have a certain understanding of the techniques for making large-format screen printing plates. This article is an introduction to the production processes and technologies needed to print 5,080 inch (1,2502,000 mm) or even larger format images. The focus will be on the most prominent areas of technological improvement in the process of making silk screens, and some alternative methods, some of which draw on the advantages of digital imaging technology.

Large format screen mesh

The large-format box, because of its large size and weight, brings some mobile difficulties to the screen printing factory. But perhaps only a bit of skill is required and these frames can be managed in an orderly manner. In the past, the best way for everyone to move a frame was to drag it on one side or corner. However, the edges or corners that come into contact with the floor will not only cause noise, but will also cause wear on the corners and the floor. It will also cause the screen to get dust, dirt, or other debris. Slight vibrations can cause loss of tight web tension. This is one of the best ways to transport large screens with wheeled vehicles or light trucks.

Please note that a large-format box is worth a few hundred dollars, equivalent to the screen version, and even if there is any carelessness, the screen will pop out of the box. Therefore, even with the help of trucks, two people are still needed to help transport and minimize potential dangers.

Another issue that must be considered is the application of large format screen printing workflow. The layout of the factory is usually designed in accordance with the principle of the most efficient use of space, and generally does not consider the use of such a large-scale frame. The point is to make the distance to move it as short as possible. The shorter the screen plate moves, the less likely it is to damage it. We must face the fact that many screen printing plants have a small space, and there is no time for rational organization. But there are many problems that can be solved by people's wisdom.

The third issue to consider is strength to weight. Manufacturers of mesh frames have been trying hard to find a balance between these two points. The question for printing companies is how to avoid or minimize the deformation of the screen. (When the tensioned wire mesh is stretched, the long side of the frame bends inwards.) This deformation will cause the screen tension to drop unpredictably. The pressure in the middle of the screen will be uneven, resulting in unstable ink transfer characteristics and Other problems. To solve these difficulties, there are usually three choices: use an ultra-wide, thick-thickened frame, a pre-bent frame, or a reinforced frame.

The ultra-wide and super-thick mesh frame can ensure that the frame longer than 120 inches does not undergo any deformation. But how many presses can handle ultra-thick and super-thickness frames with a side profile of 3x6 inches? Before choosing an extra-wide, thick-heavy screen frame, be sure to match your printing press.

The second option is to use a pre-bend frame. Some frame manufacturers are able to provide customers with long-edge pre-bend light boxes, which can help prevent deformation and maintain proper screen tension when pasting the screen.

Also, you can pre-bend the plate while straining the screen as long as your tensioner has this feature. In this case, you can bend the plate inwards. Once the screen is stretched, the net frame will maintain its pre-bend shape, ensuring the stability of the screen tension, or the net frame will return to normal shape again, increasing the screen tension.

Use a reinforced frame for the last option. This is more expensive than other options. However, they are more popular in screen printing factories because these manufacturers want to increase the strength of pull without increasing the weight, and hold the purpose of increasing the strength of the large-format frame under the premise of reducing the weight. Some manufacturers A reinforced plate has been developed.

According to their own needs to determine the advantages and disadvantages of each choice in order to make the most appropriate decision. Making a phone call to a supplier can help you to reduce a lot of confusion and find the most effective solution for you as quickly as possible.

Tension (stretching) technology

In recent years, tightening technology has made no small progress. The latest generation of pneumatic splints has made it very easy to tighten large format plates. It has a handle that is similar to a tension pliers and can support longer travel distances by which it transmits higher and more stable tension to the frame.

There are two major tension (tightening) techniques in the production of large format screens. All other technologies are based on these two technologies. The oldest and most credible method is the staged tension. Stage tensioning technology can be applied in any type of frame or stretching equipment. This method can produce the most stable screen, but it is time-consuming. In a high-speed production society, the extra time required for stage tightening technology is usually not worth it because it can only bring about a difference of 2-3 Newtons in pull. However, if time is abundant, this technology is the best way to tighten the large-format screen.

Fast tightening is another good method. This method is very good in pneumatic tensioners. Of course, other mechanical tensioners can get the same effect. This device places the screen under ideal tension or slightly high tension (2-3 Newtons high) and vibrates within the first 30 seconds to stabilize the fiber tension. Keep for 10-45 minutes, depending on the conditions of the factory. The screen version won't be stable in 10 minutes, and over 45 minutes will not benefit it.

Pulse tension is a state-of-the-art technology that is a combination of the first two methods. It has the characteristics of some stages of tension, such as strong stability, but also has a fast taut speed.

Using the method of pulse tensioning the screen, the tension of the screen is first placed at a slightly lower final tension with a rapid tensioning technique and then held for a few seconds before release. Then increase the tension and relax. Repeat this step until the desired tension is reached. This method is not very popular with everyone, but it is an effective method of tightening large-format screens. In this way, the pneumatic tightening device is no longer needed, and at the same time the fibers of the screen are prevented from coming into contact with the frame until they are fixed together. This eliminates the need to separate the frame from the screen. We recommend not to use the pulse tension method in a multi-shift system because different people will tend to tighten the plate so that the reproducibility of the plate cannot be guaranteed unless there is a strict step. Maintain stability.

If you do not consider the choice of a tight plate method, consider the manufacturer's specified tension value, but it is worth noting that for a plate of this size, it cannot be stretched to the specified maximum tension. Some wire mesh manufacturers list many acceptable tension values ​​in their product catalog. However, these are only guidelines for tightening, and many manufacturers provide values ​​for 60-inch wide screens. It is recommended to reduce the maximum specified tension of the screen above 80 in width by 15%.