Taking the commonly used hand-screen screen printing machine as an example, the working principle of the screen printing machine can be described as follows: the transmission mechanism transmits power, and the squeegee plate squeezes the ink and the screen printing plate during the movement to make the screen The printing plate and the substrate form an embossing line. Since the screen has the tensions N1 and N2, the force F2 is generated on the squeegee plate, and the resilience makes the screen printing plate not contact with the substrate except the embossing line. Under the action of the pressing force F1 of the squeegee, it is leaked from the moving nip to the substrate through the mesh.
During the printing process, the screen printing plate and the squeegee plate are moved relative to each other, and the squeezing force F1 and the resilience force F2 are also synchronously moved. Under the action of the resilience force, the screen is timely returned to contact with the substrate, so as to avoid The blot is dirty. That is, the screen is constantly in the process of deformation and rebound during the printing process.
After the squeegee finishes unidirectional printing, it is separated from the substrate together with the screen printing plate, and at the same time, returning ink is returned, that is, a printing cycle is completed. The distance between the top of the substrate and the opposite side of the screen printing plate after ink return is called the same plate spacing or mesh distance, and should generally be 2~5mm. When hand-printed, the manipulation and proficiency of the operator directly affects the formation of the embossed line. In practice, silk screen workers have accumulated a lot of valuable experience, which can be summarized as six points, that is, to ensure linearity, uniformity, equiangularity, pressure equalization, centering and vertical edge in the movement of the squeegee. That is to say, when printing, the squeegee should be straight forward and cannot be shaken left and right; it can't be slow before and after fast, slow or slow before and after fast; the tilt angle to the ink plate should remain unchanged, pay special attention to overcome the tilt angle Increasingly common problems; the printing pressure should be kept uniform; keep the distance between the squeegee and the inside of the frame equal; the ink board is perpendicular to the frame.