Screen opening and opening rate

 Screen opening and opening rate

Screen opening refers to the screen between the warp and weft space, perpendicular to the screen plane measured, is an important parameter affecting the printing accuracy.

Screen opening determines:

A screen printing ink oil in the size of the solid particles, limit the ink fine particle size.

B determines the level of detail in line and dot printing.

C ink stripping performance;

D. The thickness of printing ink layer;

Screen opening rate is also called wire mesh hole rate, effective screen area, the percentage of mesh area.That is, the unit area of the screen, the percentage of the mesh area.

0 – opening (microns);A- mesh area;A,b- width of the adjacent sides of the mesh;D – a unit length for measuring the mesh number of wires;D- diameter of wire mesh;C×D- screen area M- mesh number L- screen width

Opening rate = * 100% = ab/ab/CD/(a + d) (b + d)] = 2 / L2 (OM)

In screen printing, as offset printing dot size, to reproduce fine lines, such as 0. 1mm about the width of the line, the printing quality and mesh number has a direct relationship.When selecting the screen, the following formula can be roughly calculated to reproduce the width of the thinnest line.

K = 2 d + a

Where, K– can reproduce the width of the thinnest line:

D — wire diameter of the screen;

A — width of mesh.

The screen is stretched on the screen frame, by the action of tension, in the printing process, and by the pressure of the scraper, will make the wire diameter elongation.According to the research data, the higher the mesh number, the greater the relative tension and elongation.

Wire mesh under the action of tension elongation, resulting in thin wire mesh diameter, mesh number and opening changes.In zhang

The mesh number and opening degree under force can be calculated according to the following formula.

The mesh number M’ under tension is:

M ‘= 1 + M/elongation

The mesh opening degree O’ under tension is:

O’ =O(1+ elongation)

In the formula, M and O are the mesh number and opening degree of the screen without tension.

In screen printing play to avoid harmful screen elongation, especially in fine graphics and text printing process more so, choose

Suitable elongation of the screen screen screen printing is particularly important.