With the rapid development of screen printing, it has gained considerable proportion in the printing industry.Screen printing is one of the most important link of how to select the stencil and proper use of the stencil, because it is related to the quality of screen printing.
The criterion, and the choice of the stencil
1, the rubber hardness.Rubber hardness is usually expressed in shore hardness, shore hardness range in 55-95 degrees, in the screen printing industry, the scope also as hardness measurement standard.The hardness of the stencil from highest to lowest 5 shore hardness for arithmetic, can guarantee the stability of the printing quality.Rubber hardness of rubber shave is the degree of deformation and bending has a great influence, the coefficient of the stencil can varies because of the stencil manufacturer, this in the printing.Rubber hardness value influence of rubber shave is aligned with substrates, and decide on the stencil should put much pressure to make screen printing ink leakage.Scraping the soft glue and screen surface glue better adaptability, need the smaller the printing pressure, otherwise the opposite.
2, the stencil cross section shape.Cross section shape of the stencil is related to the size Yu Chengyin material surface pressure.Different cross section decided to ink leak too much more or less, which affects the printing ink layer thickness.Plastic cross-section shape also determines the glue shave and adaptability on the surface of the substrate, and directly affect the amount of printing ink and printing image fidelity.Glue the sharp edge, the less ink excessive leakage, printing image, the better solution as force, printing resolution is better, or you will make the printing ink layer thickness.
Second, the stencil classification
1, soft glue scrape.General in the beginning of the printing pressure, mesh opening and ink low viscosity under the condition of using soft rubber, soft is the stencil printing irregular objects and the best choice for printing on uneven printing platform.Use soft rubber printing, printing ink adhesion quantity is big, the printing image fidelity is moderate, is generally used in large area printing, ceramics and glass.Soft glue scrape the shore hardness in 55-65 degrees.
2, hardness of rubber.Printing pressure is bigger, use in the hardness of the stencil, any mesh screen and various kinds of printing ink can choose hardness stencil printing.Use of hardness rubber printing, large amount of ink adhesion, high image resolution power, suitable for all kinds of substrates material printing.The hardness of the stencil hardness shore is in commonly 65-65 degrees.
3, hard rubber.When printing pressure and ink viscosity is very high, the biggest use of hard plastic.Small amount of ink adhesion and image resolution is pretty good, usually for fine screen printing can choose blow hard rubber, its printing ink layer is very thin.The hardness of hard plastic blow shore is in commonly 75-75 degrees.
Third, how to choose a suitable stencil
In the process of printing, rubber parts in contact with the screen, the hardness of the stencil is vital for the whole printing process.
1, combination the stencil.Has a solid support body, bending in the printing, which decreases the pressure screen, and contact with the substrate surface area increased, so that the printing ink on the substrate surface coating is more uniform.Combination the stencil is the ideal choice of the high-speed printing presses, can be printed flat glass, resistance welding flux, multicolor printing ink layer and uniform UV light oil.
2, flat mouth glue scrape.Widely with ordinary materials such as paper and textile printing.This kind of adhesive is suitable for a variety of substrates and ink, and with the substrate adaptability is moderate, is due to the linear contact, so ink excessive leakage is minimal.Flat mouth the stencil is the ideal choice of the fine line printing and outlets.Ink layer thinner, printing image more detailed.
3, pointed mouth glue scrape.When printing glass and plastic is a good way to control ink excessive leakage, also suitable for the fine print of textiles.
4, slope mouth glue scrape.The container used in printing, contact with irregular surface compound is particularly good.
Fourth, the stencil grinding
The stencil edge because of frequent and screen friction damage deformation will happen eventually.Grinding scraping machine can be used to make the stencil to become sharp edges.When making the stencil grinding, should pay attention to the following:
1, using fine, fine grinding, the grinding wheel, in order to make the stencil materials in grinding when blowing loss minimum, and ensure the glue on the edge of the scraping clean, no stain, and grinding wheel rotation speed is lower.
2, when you need to quickly wear off a big piece of rubber material, can use the coarse grinding wheel for grinding.
3, if you only need to glue grinding smooth, use very fine sand paper is ok.
4, when using the cutting knife will be part of the stencil cut when needs to be polished must ensure that after cutting the stencil clean and no gap.
5, stencil printing don't immediately after grinding, to place 24 hours a day, stay solvent completely evaporate again after grinding.
6, to ensure the stencil edge grinding flat.
Fifth, the stencil store
1, the glue should be scraping gum when stored in a flat, don't into place.
Article 2, open the whole volume should be placed after 24 h, scraping the article completely stretch before use.
3, store without removing the handle when the stencil, article should be blown up, and scraping the article can't contact with any object.
4, the stencil should be stored in 20 -- 25 ℃ in dry environment, to stay away from ink, because the stencil can absorb the moisture in the air and solvent.
5, the stencil with ink or handle deposit can't spend the night.
6, the stencil don't solvent soak for a long time, although some glue can be resistant to many kinds of solvents, but long time of soaking can make the stencil temporarily out of shape, loss of elasticity.
7, finished with glue should immediately flush, to avoid the ink dry on the stencil.After cleaning the rubber handle and shave bar shall not have any residual ink marks, otherwise the stencil again when the next printing will have a mark.
8, with a soft cloth to clean the stencil, along the direction of the stencil cleaning, or reverse cleaning will damage the edge of the stencil.