Working Principle Of Screen Printing Machine

Taking the commonly used hand-shaped screen flat screen printer as an example, the working principle of the screen printer can be described as follows: the power is transmitted through the transmission mechanism, so that the squeegee squeezes the ink and the screen printing plate in motion, so that the screen printing plate and the substrate form a embossing line. Since the screen has tensions N1 and N2, it generates force F2 on the squeegee, and the rebound force makes the screen printing plate not contact the substrate except the embossing line. Under the action of the squeezing force F1 of the squeegee, the ink passes through the mesh and leaks from the moving embossing line to the substrate.
During the printing process, the screen printing plate and the squeegee move relative to each other, and the squeezing force F1 and the rebound force F2 also move synchronously. Under the action of the rebound force, the screen returns to its original position in time and breaks contact with the substrate to avoid smudging the print. That is, the screen is constantly deforming and rebounding during the printing stroke.
After completing the one-way printing, the squeegee separates from the substrate together with the screen printing plate, and returns the ink at the same time, completing a printing cycle. The distance between the top of the substrate and the back of the screen printing plate after the ink is returned is called the same plate distance or screen distance, which should generally be 2 to 5 mm. When printing manually, the operator's technique and proficiency directly affect the formation of the nip line. In practice, screen printers have accumulated a lot of valuable experience, which can be summarized into six points, namely, to ensure the linearity, uniformity, equiangularity, equal pressure, centering and verticality of the movement of the squeegee. In other words, the squeegee should move in a straight line during printing and cannot shake left and right; it cannot be slow at the beginning and fast at the end, fast at the beginning and slow at the end, or slow and fast at times; the inclination angle to the ink plate should remain unchanged, and special attention should be paid to overcoming the common problem of gradually increasing inclination angles; the printing pressure should be kept uniform; the distance between the squeegee and the inner sides of the screen frame should be kept equal; the ink plate should be kept perpendicular to the frame.