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The working principle of a screen printing machine
2020-04-28
① Taking the flat-screen, single-color, semi-automatic manual screen-printing machine with a flat-screen platform as an example, the working cycle procedure of this machine is as follows: feeding → positioning → lowering the screen plate → lowering to the ink blade and raising the ink blade → squeegee stroke → raising to the ink blade → lowering the ink blade back down → lifting the screen plate → returning ink stroke → releasing the positioning → collecting the printed item.
In continuous cyclic operations, as long as the function can be achieved, each motion should take up as little time as possible to shorten the duration of each work cycle and improve operational efficiency.
③ Imprint line. During the printing stroke, the ink blade presses against the ink and the screen-printing plate, causing the screen-printing plate to form a contact line with the substrate—this is known as the imprint line. At the edge of the ink blade, countless such imprint lines collectively constitute the printing surface. Achieving an ideal imprint line is quite challenging, as the printing stroke is a dynamic process.
③ Working principle of screen-printing machines. Taking the commonly used hand-type flat-screen printer as an example, the working principle of a screen-printing machine can be described as follows: Power is transmitted via a drive mechanism, causing the squeegee to press against the ink and the screen-printing stencil during its motion, thereby forming a printing line between the screen-printing stencil and the substrate. Due to the tension N1 and N2 in the screen mesh, a force F2 is exerted on the squeegee. The rebound force ensures that, except for the printing line, the screen-printing stencil remains completely separated from the substrate. Under the pressure F1 exerted by the squeegee, the ink passes through the mesh openings and is transferred onto the substrate along the moving printing line.
During the printing process, the screen-printing stencil and the squeegee move relative to each other. As a result, the squeezing force F1 and the rebound force F2 also move in synchronization. Under the action of the rebound force, the screen promptly returns to its original position and disengages from the substrate, thereby preventing smudging of the printed image. In other words, throughout the printing stroke, the screen is constantly undergoing deformation and rebound.
After completing a unidirectional print, the squeegee separates from the substrate along with the screen-printing plate, simultaneously returning to its original position and picking up ink—a process that completes one printing cycle. The distance between the top surface of the substrate and the reverse side of the screen-printing plate after the ink is returned is called the "plate-to-plate gap" or "mesh gap," which typically should be between 2 and 5 mm. During manual printing, the operator’s technique and level of proficiency directly affect the formation of the printed lines. In practice, screen-printing professionals have accumulated a wealth of valuable experience, which can be summarized in six key points: ensuring the squeegee’s linear motion, uniform speed, constant angle, even pressure distribution, central alignment, and perpendicularity to the edges.
In other words, during printing, the squeegee should move forward in a straight line without swaying from side to side. It should not move slowly at first and then speed up, or vice versa—alternating between slow and fast movements. The angle of inclination of the squeegee must remain constant; special attention should be paid to avoiding the common problem of the inclination angle gradually changing. Printing pressure must be kept uniform and consistent. The distance between the squeegee and the inner sides of the screen frame should be equal on both sides. Furthermore, the squeegee must remain perpendicular to the frame.
2020/04/28
What is a multi-layer belt dryer?
The multi-layer belt dryer is suitable for large-scale production of materials that are difficult to dry and have low drying rates. The equipment features a compact structure, occupies a small footprint, is simple to operate, easy to maintain, and runs with high stability. It can be designed in various hot-air circulation drying configurations according to the specific drying characteristics of the material, serving as an extension and improvement of conventional hot-air circulation ovens. This dryer is widely used in fields such as metallurgical additives, chemical industry, food processing, packaging, and others. With advancements in enterprise technology and increasing product sophistication, multi-layer belt dryers now possess the capability to meet the demands of large-scale production, diversified applications, centralized control, and continuous operation. They offer advantages such as energy efficiency and ease of management.
2020/04/28
The working principle of a screen printing machine
① Taking the flat-screen, single-color, semi-automatic manual screen-printing machine with a flat-screen platform as an example, its working cycle procedure is as follows: feeding → positioning → lowering the plate → lowering to the ink blade and raising the ink blade → scraping stroke → raising to the ink blade → lowering back to the ink blade → lifting the plate → returning stroke of the ink blade → releasing the positioning → collecting the printed material. In continuous cyclic operations, as long as the functions can be fulfilled, each step should take up as little time as possible, thereby shortening the duration of each working cycle and improving work efficiency. ③ Imprint line. During the printing stroke, the ink blade presses against the ink and the screen-printing plate, causing the screen-printing plate to form a contact line with the substrate; this contact line is called the imprint line. This line...
2020/04/28
Main features of screen printing machines
The screen-printing machine is one of the most representative types of stencil-printing equipment. Its printing plate consists of a fine mesh screen woven from materials such as silk, with clearly defined horizontal and vertical threads that intersect in an orderly fashion. A variety of screen-printing machines have been developed, including flat-bed, curved-surface, shaped, dyeing, printed-circuit, and new rotary models. Among these, the new rotary screen-printing machine boasts high speed and productivity. Its key feature is that the screen mesh is mounted on a rotating cylinder, and ink is poured into the interior of the cylinder. As the machine operates, the cylinder rotates, and a rubber blade swiftly transfers the image onto the substrate. In addition to silk, other materials such as nylon filaments, copper wires, steel wires, or stainless steel wires can also be used to make screen meshes. The principle of stencil printing employed by screen-printing machines originated in ancient stenciling techniques. Stencil printing encompasses several forms, including mimeograph, openwork stencils for spray painting, and screen printing itself. Early screen-printing was performed manually, using just a single frame, a single screen mesh, and a single stencil. It wasn't until the 1950s that screen printing began to be mechanized and automated. Rotary screen-printing machines apply large amounts of ink during printing, making them ideal for producing prints with thick ink layers. They can print on a wide range of substrates—including various types of paper, glass, wood boards, metals, ceramics, plastics, and fabrics—and support the use of multiple types of ink, including conductive metallic inks.
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