1. Actual printing ink penetration:

The thickness of the film (determines the amount of ink). If we use photosensitive glue to make the screen, we must also consider the solid content of the photosensitive glue itself. After the photosensitive glue with low solid content is made, the film will be volatilized and the film will become thinner. Therefore, we can only use a thickness gauge to detect the overall thickness of the stencil.

2. The viscosity of the ink (indirectly affects the thickness of the ink layer). The lower the viscosity of the ink during the printing process, the thicker the ink layer will be, because the ink itself contains less solvent, on the contrary, the thinner.

3. The blade edge (directly affects the amount of ink). The blade of the squeegee is at a right angle and the ink drop is small. The ink volume is large if it is at an obtuse angle.

4. The pressure of the squeegee (directly affects the amount of ink). During printing, the greater the pressure applied to the squeegee, the smaller the ink drop, because the ink has been driven away before being completely squeezed out of the mesh. On the contrary, it is small.

5. The tension of the screen (affects the size of the opening, the number of screen meshes, the wire diameter, and the thickness of the screen). In the process of stretching the screen, as the tension increases, the technical parameters of the screen itself will change accordingly. First, it affects the mesh number of the wire mesh, the higher the tension, the greater the drop in mesh size (until the mesh is plastically deformed). Next, it will affect the hole width of the screen, the mesh will become larger, the wire diameter will become thinner, and the mesh cloth will become thinner. These factors will eventually lead to changes in the amount of ink.

6. Ink type (indirectly affects the thickness of the ink layer). We know that after solvent-based ink is printed, the solvent will evaporate and the final ink layer will become thinner. After printing, the resin is cured immediately after being irradiated by ultraviolet rays, so the ink layer remains unchanged.

7. The hardness of the squeegee (indirectly affects the thickness of the ink layer). In the printing process, the higher the hardness of the squeegee, the less easily deformed, the smaller the amount of ink, and vice versa.

8. The angle of the scraper. (Indirectly affects the thickness of the ink layer). During printing, the smaller the angle between the squeegee and the screen, the greater the amount of ink, because the squeegee and the screen are in surface contact. On the contrary, it is small.

9. The pressure of the ink-return knife (the amount of direct ink). The greater the pressure applied to the ink-returning knife, the greater the amount of ink, because a small amount of ink has been squeezed out of the mesh by the ink-returning knife before printing. On the contrary, it is small.

10. Printing environment (indirectly affects the thickness of the ink layer). One issue that we have always overlooked is the change in temperature and humidity of the printing workshop environment. If the temperature of the printing environment changes too much, it will affect the ink itself (such as ink viscosity, mobility, etc.).

11. Printing materials. (Directly affects the thickness of the ink layer). The flatness of the substrate surface will also affect the thickness of the ink layer, and the rough surface ink will penetrate (such as woven fabrics, leather, wood). The opposite is greater.

12. The speed of printing (indirectly affects the thickness of the ink layer). The faster the printing speed, the smaller the ink drop. Because the ink has not completely filled the mesh, the ink has been squeezed out, causing the ink supply to be interrupted.

2. Analyze the theoretical ink penetration:

There are two methods to analyze the ink penetration of the screen, one is to calculate the theoretical ink penetration of the screen, and the other is the actual printing ink penetration. There are the following formulas for calculating the theoretical ink penetration: open hole ratio: L screen thickness: D theoretical ink penetration: M=L×D÷100% The above formula is only a theoretical method of calculating the screen ink penetration, once When applied to practical printing, the data will change, but in direct proportion. We look at the following factors:

1. The mesh number of the screen (directly determines the hole width and opening rate). The higher the mesh number of the screen, the smaller the hole width, and the opening rate will decrease accordingly. For example, the hole width of the 355 mesh screen is 31μm, the opening rate is 26%, and the theoretical ink penetration is 14.3cm3/m2. 305 mesh The screen hole width is 45μm, the opening rate is 35%, and the theoretical ink penetration is 16.3cm3/m2.

2. The thickness of the screen (directly affects the ink layer). We can use a thickness gauge to measure the thickness of the stretched screen. Because the wire mesh produced by each manufacturer has its own weaving process, the warp and weft yarns have different degrees of curvature. The greater the degree of curvature, the wire mesh will become thinner, and vice versa. In the process of stretching the screen, the wire diameter is stretched due to the influence of external force, which will ultimately affect the thickness of the screen.

3. The opening rate of the screen (directly affects the amount of ink). The so-called open porosity refers to the white ratio of the ink permeable area to the total area in the unit area of the screen. For example, a screen with an opening rate of 35% has an ink-permeable section of 35%, and an impermeable section that is blocked by the silk screen is 65%. A screen with a higher opening rate has a greater amount of ink.

4. The pressing plane of the screen (directly affects the screen thickness and hole width). Flattening is often used for entrance screens above 355 mesh. The flattened wire mesh will become thinner and smaller. When the flattened screen is stretched, let’s take a look at the following example: When the pressing plane is stretched toward the scraping surface, it can save ink by 10%~15%, and when the pressing plane is stretched toward the substrate surface, it can save ink by 15%. ~25%.

5. The opening rate of the screen (directly affects the amount of ink). The so-called open porosity refers to the white ratio of the ink permeable area to the total area in the unit area of the screen. For example, a screen with an opening rate of 35% has an ink-permeable section of 35%, and an impermeable section that is blocked by the silk screen is 65%. A screen with a higher opening rate has a greater amount of ink. Calculation formula: Hole width: K Mesh number: M inches Unit: Y Hole rate: L=K×M÷Y2×100% 6. Wire mesh diameter (directly affects mesh thickness and hole rate , Mesh size). It refers to the diameter of the unwoven wire diameter, and the wire diameter after weaving will become oval. Will affect the size of the mesh. The different wire diameters of the same mesh will also affect the opening size and opening rate.

3. How to calculate the thickness of the ink layer?

Through the above discussion, we know that if a certain link changes during the printing process, it will eventually lead to inconsistent ink volume. How should we calculate the thickness of the ink layer? One method is to weigh the weight of the wet ink. First, try to keep every link in the printing unchanged. After printing, weigh the weight of the substrate, and then subtract the original weight of the substrate. The data obtained is that of the wet ink. For weight, another method is to measure the thickness of the ink layer. Use a thickness gauge to measure the thickness of the substrate after covering the ink, and then subtract the original thickness of the substrate. The data obtained is the thickness of the ink layer. 4. How to control the thickness of the ink layer? How to control the thickness of the ink layer during the printing process of the screen printing machine has become a problem faced by the screen printing industry. The first thing we have to do is to use the existing measuring equipment to ensure the correctness and objectivity of the measured data; An automatic coating machine can be used to complete the gluing process to ensure the thickness of the glue layer.

The next thing to do is to ensure that every link in plate making and printing remains unchanged as much as possible. Each printing parameter should be recorded to provide ideal data for finding the right ink layer thickness, so that the screen printer can print better. Smooth and reduce errors.