Aluminum alloy screen printing technology

There are many kinds of metal and metal products. For the convenience of narrative, this book still uses the aluminum alloy sign screen printing process as a typical process, and introduces the metal screen printing process. The screen printing process of other metal products is almost the same as the screen printing process of aluminum alloy products. This book does not introduce more.

The screen printing process of aluminum alloy signs is roughly as follows:

Screen printing plate production (draft drawing, making bottom version, selection network, stretch net, coating (paste) photosensitive film) -

Printing material preparation (under the material, prepress processing, positioning)————————————→

Screen printing—→drying—→coating protective paint—→protecting film—→blank molding (high-light processing)—→ inspection—→packaging

In the production process, the most critical are the three processes of “bottom plate”, “pre-processing” and “screen printing”. The plate making process determines the quality of the signage.

1. Make the bottom plate. Most of the text and graphic plates of the signage are phototyped and photoengraved, and the original one-piece is produced first, and then even the air-jet printing machine is used to make the imposition. When imposition, it is possible to use pitchless imposition and pitch imposition according to the accuracy of the parts required. Signage size requirements are not high, can be used for imposition, as shown in Figure 4-12. After printing, it can be directly cut or cut and stamped and formed.

If there is a high requirement for the accuracy of the signage, a pitched imposition shall be used. After the printing is completed, punching and forming shall be performed according to the position of the positioning hole, as shown in Fig. 4-13. The distance between each part can be 2mm, the positioning aperture can be 2mm hole spacing 4mm, the overall area can be 400x400mm, or depending on the process design.

If the color of silk screen label is two or more than two colors, the photo base should have positioning rules, and the positioning hole can be drawn on the photo plate of the main pattern of the sign so as to ensure the accuracy of positioning when punching.

2. Positioning. The rules on the printing plate of the silk printing plate are the technological means to ensure that the position of the figure on the same surface of the printed workpiece is accurate, uniform and satisfies the requirements for the color overlay accuracy. According to the different materials and shapes of the substrates, the positioning methods of screen printing labels are also different. The following are commonly used:

1 Edge positioning. Suitable for straight-edged workpieces, such as: nameplates, panels, various dials, etc. When the screen is printed, the two right-angled edges of the workpiece can be placed against the positioning bar.

2 flange positioning. It is suitable for screen printing of different shaped workpieces. It can form the outer frame of workpiece blanking. After trimming the clearance, press the edge positioning method to adhere the outer frame to the required position on the platform. When the silk screen is printed, it is only necessary to put the shaped workpiece into Blanking frame can be.

3 hole positioning. Hole positioning applies to the same pattern of imposition silk screen, that is to punch out the positioning hole in the plate, when the screen is printed, the hole is positioned, and finally the mold is blanked and formed by the positioning hole.

4 coincident positioning. Suitable for silk screen printing on transparent materials. Positioning, the second color pattern may be silk-screened on the cardboard, and covered with the film printed with the first color pattern, so that the same position of the two-color pattern meets the design requirements, and then the film and the platform with the first color pattern are printed. When the second color pattern is screen printed, it is only necessary to overlap the transparent workpiece with the first color pattern and the first color pattern on the platform, so as to achieve the purpose of positioning.

3. Ink deployment. The requirements for screen printing inks for metal signage are strong adhesion, good abrasion resistance, clear graphics after printing, fast drying, and no net sealing. Metal marking silk screen printing oil is generally used alkyd, phenolic and other synthetic resin as a linking material, add some of the pigment, additives and other special ink. The printing performance of this ink is good, and it can be dried naturally after printing or baked at 120°C for 2 hours. Its ink film surface is bright and three-dimensional, and it has excellent adhesion and wear resistance with aluminum plates. The ink film of this kind of ink was tested with a JM-l paint film wear instrument. The rubber wheel with a load of 7509 can be pressed for more than 500 times and can be grinded with a cloth wheel for more than 5000 times.

If the screen is printed with a color sign, reference may be made to the color ink of the color printing ink. When the ink is transferred, the appropriate amount of the ink and the desiccant should be added. The ink desiccant is added in an amount of about 5 to 8% of the total amount of the ink. Adding less is not easy to dry, and adding more affects the adhesion of the ink.

4. Quality requirements for silk screen labels. The text, scale, graphics, positioning holes, and color of the screen printing label shall meet the requirements of the drawings. The surface of the finished product shall be free from obvious scratches and stains, and the adhesion of the ink film shall meet the requirements.