Problems That Should Be Paid Attention to in Making Screen Plates
1. Select the frame
The first thing to consider when selecting the frame is that the frame must have mesh tension resistance and a certain degree of strength. The bending deformation should be limited to the allowable range. In the process of plate making and printing, the frame must be in contact with water and ink. Therefore, it is required that the frame should have sufficient water resistance and solvent resistance; in order to maintain the stability of its performance, the size of the frame should be larger than the graphic part of the plate, and the marginal part should be set to 8 to 25 mm.
2. Select the screen mesh
Screen mesh plays a decisive role in the quality of printing. The mesh number, hole width, wire diameter, thickness, and through hole rate of the screen mesh must meet the ink penetration requirements of the printing. Within a certain limit, the thickness of the ink layer should be able to match the width of the mesh hole, the thickness, and the through hole of the screen mesh. The increase in the rate, wire diameter, and the number of meshes decreases.
The screen mesh will affect the clarity of printed graphics. The finer the screen mesh, the more favorable it is for the subtle levels of graphics. So consider choosing the silk screen mesh with the finest lines printed. In addition, the direction of the screen mesh of the screen is also very important, that is, there must be a certain angle between the screen mesh and the text, between the squeegee and the screen mesh, and should be arranged in a non-parallel form.
When performing multi-color screen printing, the number of screen meshes must match the number of screen lines. In order to accurately reproduce the level of the image, the screen mesh should be able to support the smallest dot of the image highlight area to ensure that each dot is larger than the screen mesh, so that it will not fall into the mesh and disappear. Due to the constraints of screen accuracy, the number of screen lines should generally be less than 50 lines/cm, and the percentage of screen points should be between 9% and 90%.
When selecting screen mesh, the properties of the printing material and the ink should also be considered.
3. Correct use of squeegee
The squeegee squeezes the ink and the screen plate in the squeegee process to contact the screen plate with the substrate to form a contact line with a certain width. When the squeegee is moved, the screen plate is ejected from the substrate. The smaller the width of the contact line is, the better, and the faster the screen is ejected from the substrate, the better.
The material, shape and hardness of the squeegee can also affect the printing effect. The material of the squeegee is determined by the properties of the printing ink, and the shape depends on the printing material and printing requirements. The hardness of the squeegee and the angle of the squeegee have a great influence on the ink amount, and the squeegee with a soft or low hardness and a relatively blunt angle has a larger amount of ink. The smaller the squeegee angle, the greater the amount of ink delivered. Choosing a reasonable squeegee angle during printing can achieve the best match between squeegee and screen, printing speed, ink viscosity and other factors. The squeegee angle is generally between 50 and 85°.
Screen printing pressure includes the pressure between the squeegee and the screen, and the pressure between the screen and the substrate. When printing, it is necessary to properly control the pressure between the squeegee and the screen, so that the ink can smoothly pass through the screen to the surface of the substrate. Squeegee pressure and screen pressure have a greater impact on ink transfer performance. Within a certain pressure range, the amount of ink transferred increases with the squeegee pressure and screen printing force.
4. Control the printing speed
The slower the printing speed, the greater the amount of ink transferred. If the printing speed is too fast, the ink will be able to pass over the top of the screen mesh, not fill the mesh, and it will not be able to transfer ink.
5. Adjust the screen distance correctly
Screen distance refers to the distance between the screen and the substrate. It determines the tensile deformation of the screen and affects the squeegee pressure, the screen pressure, and the resilience of the screen in the printing state. The optimal distance should be the minimum distance that satisfies the resilience requirements of the screen.
6. Overprint accuracy
The overprint accuracy of the screen printing is susceptible to the direction of movement of the transverse squeegee, causing misalignment and tensile deformation of the image, as well as tensile deformation in the longitudinal direction of the squeegee.
When the screen is pressed down and contact with the surface of the substrate, the screen image may be misaligned due to the improper position of the screen and the printing surface during printing. When the layout of the horizontal layout in the horizontal direction is misaligned, a graphic deformation will occur. The change depends on the pitch and the position of the squeegee.
The longitudinal deformation of the printed image is consistent with the tensile deformation of the screen, and the same size is maintained at different positions on the screen. The amount of tensile deformation depends on the length of the squeegee and the web spacing. When printing, it is necessary to reduce the distortion of the screen image as much as possible so that it is limited within the scope of the printing accuracy requirements, so that an ideal print can be obtained.
Choose the suitable and high quality meshes
The printing plate is most important for screen printing, and the screen mesh is the core of the screen printing plate. No matter how good the frame is, if the mesh is not good or suitable, it will seriously affect the printing effect and customer experience. Wuxi Jinfeng Silkscreen Mesh Manufacturing Co., Ltd. specializing in the production of high quality screen mesh and filter mesh, with more than 20 years of production experience, the products throughout the country’s major mining companies and overseas. And get the praise from all the clients.
WUXI JINFENG SILKSCREEN MESH MANUFACTURING CO., LTD.
Since 1996, as professional we manufacture high quality meshes at best price!
Address: Jinxin industrial zone, xibei town, wuxi city, jiangsu province, China 214194
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