Transfer printing in the injection molding plant

The transfer printing in the injection molding plant uses the principle of intaglio printing. The tools include silicone rubber heads, printed plates (steel or fiber) with patterns and ink, which can print various fine lines, fonts and patterns, and even four-color screen images. Whether the surface of printed matter is concave, convex or irregular, the ideal injection molding process effect can still be obtained. 1、 Injection process flow chart of pad printing Pattern design → output film → decoration and engraving of steel plate → installation of pad printing machine and steel plate → installation of cleaning oil scraping system (oil pan and scraper) → allocation of ink → adjustment of pattern pad printing effect → production of pad printing and injection molding process → inspection → packaging. 2、 Pad printing equipment

1. Pad printer The pad printing machine is the core of pad printing production. It uses compressed air as the original power, uses electrical signals to control the rubber head movement and pad printing action program to print monochrome or overprint two-color to multi-color patterns, and can carry out 1~3 times of flow printing, 1~2 times of color rotary printing and 2~6 times of color push plate printing. Dongguan Matchko Injection Molding Factory selects the pad printing machine according to the area and volume of the printed object, selects the functions of monochrome, two-color or rolling printing according to the needs, and selects the dial and keys according to the machine operation instructions, determines the corresponding functions and sets the injection molding process parameters.
2. Steel plate Dongguan Matchke Injection Molding Plant generally uses chrome steel with hardness above 60 degrees. The etching depth of the printing plate is 0.015~0.035mm, and the thickness of the transfer printing ink film is 0.004~0.008mm. It depends on the etching depth of the printing plate type and the hardness and shape of the printing head. Other factors such as temperature, humidity and environment may also cause differences in the thickness of the ink film. The size of the printing plate is measured by the area of the printing pattern. Generally, the area of the printing plate should not be too large, otherwise it is difficult to fix the steel plate on the oil pan.
3. Ink scraper Rockwell hardness is about 55 degrees (not more than steel plate).
4. Ink (1) Different ink shall be used for plastic parts with different injection molding process materials. (2) Understand the gloss, covering power and solidification rate characteristics of the ink. (3) The ink shall not corrode the pad head. (4) The rate of ink solidification should not be too fast, otherwise it is easy to dry in the oil pan. At this time, solvent can be used to dilute. If you want to speed up the drying rate, you can use quick-drying agent or hair dryer to assist. (5) The ink should be mixed to a proper viscosity. If the ink is too sticky, the lack of activity will lead to printing difficulties; If the ink is too thin, the printed pattern color is not clear enough or the line is poor; Therefore, ink blending is an important work.
5. Rubber head The rubber head is generally made of silicone rubber, with a Shore hardness of 25~65. The effect of hard printing and injection molding process is relatively good, and the image and text are not clear enough. The size and volume of the pad printing head are too large to waste. Different types of pad printing heads are required for plastic parts of different shapes. The shape of the transfer rubber head is adjusted according to the unevenness of the transfer rubber part. The transfer rubber head should carry the ink on the flat steel plate to the uneven printed part, then the end of the transfer rubber head should be very elastic, and the shape of the transfer rubber head must be suitable for the width of the plastic part, so that the pressure on the end of the transfer rubber head can be evenly diffused to avoid the transfer rubber head being inclined to print on the plane of the plastic part. 3、 Process of pad printing The process of pad printing is as follows. (1) The ink scraper will apply the ink to the etched concave, and the blade will scrape the ink on the steel plate back into the ink container during the return journey. The ink on the etched pattern will increase its surface viscosity after evaporation. (2) The printing rubber head moves downward to contact with the printed etching pattern. (3) When the printing rubber head rises, the ink in the etched pattern is sucked onto the rubber head. (4) In the process of moving the printing head from the steel plate to the printed part, the attached ink bath agent gradually volatilizes, making the viscosity of the ink increase again, and the rubber head stays at the horizontal position above the plastic part. (5) The printing rubber head is pressed down on the printing plastic part to transfer the ink attached to it to the injection molding process surface of the plastic part. (6) The printing head rises again to the original position above the plastic part. The requirements of road printing on the substrate are the same as those of screen printing on the substrate. The pad printing does not need to be dried with a special heat source, but can be dried naturally or by air. The quality inspection of the injection molding process of the transfer printing pattern is basically consistent with the requirements of the screen printing. 4、 Effect of transfer printing pattern (1) Color: 1~7 colors can be pad printed at the same time. (2) Gloss: generally only semi-gloss or matte effect can be printed. (3) Covering power: due to poor covering power, the fidelity of color is not very good, and the interference of background color is obvious. (4) Multi-color register printing: The accuracy of the register depends on the accuracy of the pad printing machine and the manufacturing accuracy of the fixture.#transferprinting #injectionmoulding #injectionmachine #plasticinjection