Surface printing machine operation steps
There are many mechanical devices used for surface printing, and its transmission methods are manual, electric and pneumatic. Manual printing presses can only be used for small batch printing because of the slower printing speed. The compact size of the electric curved printing presses and the low noise during printing are very popular with screen printing manufacturers. However, most manufacturers still use pneumatic curved surface printing presses. The following takes the Henghui S250M curved surface screen printing machine as an example to talk about the operation steps of prepress screen debugging and printing.
Determine the stroke distance
After installing the dried screen plate into the grid, the left and right positioning stoppers on the slide frame should be loosened, and the screen plate should be moved to the left. The distance between the ink-returning blade under the blade holder and the printed graphic is 10 ~ 20mm, then lock the left positioning stopper, and then move the screen plate to the right. The sharp blade under the blade holder should exceed 10~20mm in the printed graphic and then lock the right positioning stopper. After connecting the circuit and the air circuit, press the “Net Box Test†button on the operation panel to observe whether the frame operation is stable (no shake) and whether the distance from the scraper and the ink return knife is reasonable and accurate.
Turn on circuit and air circuit
First turn on the power switch, then pull the airway through the valve back, the airway will be open. In the printing process, it is inconvenient to reuse the "single-cycle" key on the operation panel. Printing workers often use the foot switch to perform single-cycle work. In this way, it is possible to artificially control the time for loading and unloading the substrate, so it is also necessary to Connect the foot switch to the circuit firmly (there is a reserved special socket on the base) and finally connect the air compressor power.
Network distance debugging
The difference between aerodynamic curved surface printing machine and flat surface printing machine is that its printing platform can move up and down. When the printing platform goes down, we can put the substrate into the bearing frame and wait for printing. When the working platform rises, it can be carried out. Scratch. The debugging of the network distance must be cautious and careful, and must not be rushed. Otherwise, the substrate collided with the screen will cause damage to the machine components. First, press the "Lift" button on the operation panel. At this time, there is a certain distance between the raised working platform and the printed screen. Use a caliper to measure the distance between the top of the bearing and the screen. If the measured value is greater than or equal to the diameter of the substrate, the substrate can be placed on the bearing frame for a second adjustment. If the distance between the substrate and the screen is still greater than the value we need, the platform lifting wheel on the base can be turned clockwise to lift the table upwards until it is satisfied (Substrates and Webs) The distance between the plates should be controlled between 1 and 1.5mm.
Adjustment of Scraper, Ink Blade and Rotation Centerline of Substrate
Raise the working platform so that the distance between the printing material and the screen is 1~1.5mm, then loosen the screw between the top frame of the razor frame and the frame support so that the frame rest will fall, and the squeegee and the net in the frame will be scraped. When the distance between the plates is 1mm, lock the screws. Press the “Squeegee Adjustment†button on the operation panel, the air circuit is connected, the blade falls into the screen, observe whether the blade is in contact with the substrate (turn the substrate by hand, the substrate rotates and there is a certain gap between the substrate and the screen). Friction). If there is a deviation in the distance, adjust the setting screws on the squeegee cylinder to make the best contact. The adjustment of the ink-jet knife is also the same as the adjustment principle of the doctor blade, except that the ink-repelling knife cannot be cut into the screen; it should be kept parallel to the screen plane, and the best position is between 0.2-0.4 mm from the screen screen.
The height of the blade is based on the rotation center line of the substrate. When the blade is in contact with the substrate through the screen, the blade line and the rotation center line are the same line. During the printing process, the scraper line should be constantly corrected. Whether the substrate rotation centerline of the substrate is reunited together can guarantee the quality of printed products and improve the production efficiency.
Tapered printing
Because the open surface and the bottom surface of the taper substrate are not equal, the work platform must be tilted so that the substrate can be printed parallel to the screen. There is a taper adjustment screw at the bottom of the working platform. Adjust the height of this screw to tilt the working platform to the angle we need.
In addition, the graphics of the taper substrate are arranged in a fan-shaped pattern on the screen. When the computer is used to design the graphic and text, it is necessary to accurately draw a fan-shaped outline and fill the outline with a graphic.
Ink test
At the beginning of the screen, a small amount of ink is smeared with a squeegee blade and the "single cycle" button (or foot switch) is pressed on the operation panel. At this point, the squeegee falls and contacts the substrate and is fixed on the gliding frame. The screen frame is leftward to scratch, and when the image is exceeded, the block is blocked by the positioning block, the blade lifts, the ink blade falls, and continues to the right. After the ink returning task is completed, the screen rack stops at the starting point. When we take out the prints, we should carefully check whether the inks in the graphic and text are even and bright, and the color is accurate. If any problems are found, we should promptly find out the reasons.
Water transfer printing process
Since the glass material is fragile, it brings difficulties to the production of molds and fixtures. The glass products are different from the plastic products produced by the injection molding process. The injection molding has already been positioned and the glass products themselves are in the firing process. There is a deviation in size, which adds a lot of difficulty to color printing, and it is not easy to overprint very accurately.
For irregular surface prints, printing with a curved press is not possible at all. Water transfer printing is generally used. The ceramic and glass water transfer ink produced by Japan's Tanaka Chemical Co., Ltd. has stable quality, bright ink layer, and good fastness. It can be printed by hand or mechanically. The printing process flow is as follows: Water Transfer Printing Paper Printing Cold Water Adhesive Watermark Text Pattern Printing oil printing cover oil is transferred to the substrate.
Several problems that should be paid attention to in operation
1. According to the pattern size of the substrate, select imported or domestic water transfer papers of different grammage. The transfer paper should be aired in advance (sunshould not be directly exposed) so that the moisture absorption rate of the paper can be synchronized with the temperature and humidity of the printing shop, so as to ensure overprinting Accuracy.
2. The mesh size of the three screens of glue, pattern and varnish must not be less than 250 mesh/inch (1 inch = 2.54 cm). Otherwise, the printed ink layer is too thick, there are traces of ink on the ink layer, affecting the appearance of the quality of printed products. The cover oil is generally printed with a 100 mesh/inch screen. If the pattern area is large, it can be printed twice, so that the cover layer does not break easily when the slide is pasted, and the quality of the transfer can be guaranteed.
3. After the transfer is completed, the moisture between the substrate and the sticker must be eliminated. The soft scraper and the latex sponge can be used for scraping and pushing. Partially raised small blisters can be drained by acupuncture. The process of scraping moisture is directly related to the integrity of the pattern of the water transfer printing product and must not be underestimated.
4. The water-squeezing product with scrape clean water can be sent to the oven of 50~60°C in the workshop for 10 hours and baked. After baking for 20~30 minutes, it will be removed. Immediately after the temperature drops, the cover layer will be torn off and then put again. Into the oven (180 ~ 200 °C), keep 30 ~ 40min, the ink layer can be completely dry, and bright and strong, solvent resistance and friction.
5. The high-temperature sintered ink (glass glaze) can be fused with the glass surface after firing. Therefore, it has high solvent resistance, chemical resistance, and scratch resistance, and is often used to print high-grade daily life. Drinking utensils and glass products needed for special occasions.
Sintered ink can be directly printed on glass products, but an oven needs to be purchased. When the temperature of the furnace rises to 550°C, the glaze can be completely melted and the glass is fused together. Therefore, its fastness to adhesion is in all glass. The best ink. The high-temperature sintering ink transfer process flow is: water transfer paper → printing graphics → printing cover oil → transfer to the substrate. The release layer formed after the cover oil is dried can be volatilized (200°C or so) as the furnace temperature rises, without artificial tearing.
The printing process of curved glass products is relatively complex, and corresponding printing methods are used for different shapes of objects. At the same time, many fixtures and dies are needed. The printing of glass products can also use pad printing technology, but the manufacturers of printing glass ink in China are very There are many private manual screen printers that can be made by civil craftsmen. It is also very convenient and quick to use. In short, as long as we master the process principle of surface printing, and constantly explore and accumulate experience in practice, we will be able to print beautiful and colorful images.