Screen screen spacing and its impact on printing quality 2021-04-27

If the screen plate adheres to the substrate, it can cause many problems. The screen spacing solves this problem. During the printing process, it can make the screen only come into contact with the substrate at the blade of the scraper. Once the scraper passes through this area, there is a peeling area where the screen separates from the substrate, leaving a clear print. Stripping refers to the upward separation movement of the screen frame during the printing process, which occurs at the starting point of the ink scraping stroke and during the printing cycle when the ink scraping plate is in motion. The screen plate is moved until it comes into contact with each pad, and different pads are used to adjust the screen spacing. Calibration wedges can also be used to adjust the screen spacing, which has good accuracy and universality.

Use a mechanical mesh gauge. Suspend the reticle gauge above the screen and make the reading of the instrument on the screen surface 0. Then press down until the screen and substrate come into contact. Read the value at this point from the instrument and subtract the thickness of the screen and template to obtain the reticle gauge at this point. As long as used properly, the data measured by the net distance meter is very accurate and has good repeatability. Its disadvantage is that each reading must be readjusted, and the instrument is limited to moving around the screen, making it inconvenient to use and difficult to use on some printing machines. At present, the Screen Printing Technology Foundation (SPTF) has launched a new type of instrument for measuring screen spacing, which is a more effective and reliable electronic testing instrument that can quickly and accurately measure screen spacing at any position on the screen, with simple operation. The operator of the prepress process can use this instrument to know the size of the mesh distance at any time.

The variables that affect screen spacing include frame size, screen tension, scraper length, image area relative to frame size, and image type (such as large field and reverse images, which require a larger screen spacing due to the large surface area in contact with the substrate). Some of these variables can be changed, while others cannot. The printing substrate operator should make corresponding adjustments according to the requirements, and the screen spacing should be as small as possible within an acceptable range. The tension of screen printing is a factor that affects the adjustment of screen spacing and is also an important factor affecting printing quality. This should be considered during plate making, but the impact of tension on the lifespan of screen printing only manifests during printing. If the tension of the screen is too low, the screen is prone to debonding under continuous stretching. In addition, in order to enable the screen to bounce up quickly, it is necessary to increase the screen spacing, which requires a corresponding increase in the pressure of scraping. However, this undoubtedly makes it easier to damage the screen and deform the pattern. Generally, the adjustment of net spacing should be based on the tension of the tension net. If the tension is large, the net spacing will be small, and if not, it will be large; According to the size of the frame, the distance between the larger frames also increases. However, it should be noted that when adjusting the network distance, it is necessary to ensure that the network distance of each point on the screen is consistent.