In the process of screen printing, the plate making process is the key link. The first step of screen making preparation is the selection of screen, which relates to the quality of screen and production efficiency. Let's share the selection of screen.

1、 Selection of mesh size:

Three factors need to be considered: ink used:

① General water-based ink is suitable for thicker screen (125-180 mesh / inch) (inch is the length unit 1inch = 1000mil = 2.54cm = 25.4mm); ② Medium mesh screen (196-420 mesh / inch) shall be selected when printing advertisements and electrical appliances with solvent ink; ③ UV ink adopts high mesh screen (355-457 mesh / inch); ④ Generally, the pigment particles of the ink are relatively fine, and the ink has a good pass through property. This ink can also pass through well when using a high mesh screen; And the ink with high pigment concentration, although the particles are fine, will have poor permeability.

Type of substrate:

① The absorbent substrate with rough surface needs more ink to achieve a good coverage of the ink layer, so a thicker screen is selected; ② The non absorbent substrate with smooth surface needs relatively less ink, so a higher mesh screen is selected.

Match the number of screen mesh with the original image: the number of screen mesh selected should be sufficient to protect the image on the plate, that is, ensure that there is enough screen support in the thinnest image area. (the width of the fine line that can be printed on a certain number of screens is equal to the sum of the mesh aperture and the screen diameter plus the expansion of about 7% during screen weaving. (for example, for a screen of 180 mesh / inch, the mesh aperture is 23 μ m. Wire diameter: 30 μ m. Printed to thin line width = 23 30 (23 30) 7% ≈ 57 μ m。 It shows that this kind of screen can only print lines of 57 microns when it is thin. There is also a formula that the thickness of the screen can be completely printed to small dots (or lines) = √ 2 * (1 mesh of the screen * wire diameter) mesh of the screen).

2、 Selection of wire diameter: two aspects shall be considered: ① tensile strength of wire mesh. ② The fineness of the original.

When the number of mesh is the same, the larger the wire diameter, the stronger the tensile strength, wear resistance and corrosion resistance, and the larger the thickness, the smaller the opening area (opening rate). When the origin size of the original image is twice the wire diameter, the dot may fall on the screen, and the dot loss in the highlight area is heavy. When the dot is 3 times the wire diameter, any part of the dot can be supported enough, and the dark tone dot can also get enough opening area.

3、 Problems to be paid attention to when selecting wire mesh:

Uneven weaving; Uneven thickness of wire mesh; The cost of selecting wire mesh; Pay attention to moire:

In halftone screen, the screen will also affect the degree of Moire printed.