Inspection of organic glass print quality

Only the following four functions of the squeegee in the screen printing process of plexiglass craft products are well performed, so that high-quality organic glass craftworks can be printed. The physical properties of the scraper play a decisive role in the above functions. (For example, a harder squeegee can well scrape off excess ink, but it does not meet the requirements of different plexiglass product shapes well). Therefore, when selecting the squeegee, the influence of the squeegee performance factor must be fully taken into consideration to avoid adverse effects on the printing effect. When choosing a suitable performance squeegee, consider the following four factors:

1. Hardness: The squeegee is usually made of polyurethane and the hardness of the squeegee is measured with a durometer. The hardness, size, and shape of the squeegee determine the bendability, flexibility, and pressure of the squeegee. Hardness ranges from 55 degrees to 90 degrees (Shore A). The hardness value was measured with a Shore A hardness meter. 55A-65A is a low hardness squeegee, 66A-75A is a medium hard, more than 75A is a high hardness.

The high hardness squeegee is very advantageous for the first three functions of the squeegee. The ink is pressed into the screen and the ink is transferred from the fine stencil to the substrate, and the stencil is kept in line with the plexiglass sheet. The only defect of high hardness squeegee is that it cannot satisfy the printing of plexiglass products with different shapes. When printing rough surfaces and uneven surfaces, the quality requirements for squeegee are also high.

2. Effective Width: refers to the width of the squeegee extending from the aluminum squeegee into the aluminum scraper handle. This width is important and determines the curvature of the squeegee under pressure. Bend is the cubic value of the effective width. For example, twice the effective width is the curvature greater than 23.

The squeegee bend can cause two changes: the angle between the squeegee and the screen; the printing pressure transmitted to the plexiglass article is reduced. For example, the squeegee is likened to a set of springs. When the spring is forced at an angle, the spring begins to bend, and the transmitted force is getting smaller and smaller. Squeegee printing angle is reduced, printing pressure is insufficient, and the printing effect is not ideal. The printing angle is small, the printing pressure is reduced, the amount of ink is large, and the ink layer is thickened. (In this case, the printing operator will increase the printing pressure, the curvature of the squeegee increases, and the resulting ink layer is still not ideal. The solution is to increase the hardness of the squeegee and increase the angle of the squeegee.) This is the effectiveness of the squeegee. The effect of width on the four functions of the squeegee.

The effective width of the squeegee is usually between 20 MM and 30 MM. The choice of the best effective width is based on the flatness of the plexiglass article, screen image resolution, and other printing parameters such as squeegee angle, speed, and ink type. When printing high resolution images on flat/smooth substrates, the effective width is small (less than 20mm), high hardness, and fast printing with suitable ink. In uneven, rough plexiglass, the effective width should be increased (sometimes 30MM), the hardness should be reduced, and the low hardness squeegee should have poor adaptability, and should not be excessively curved. You can also use the middle hard and soft three-layer scraper or double. Scraping. In general, the effective width increases, the printing speed decreases, and the printing angle is increased.

3. Squeegee shape:

The squeegee shape refers to the cross section of the squeegee. Most squeegee shapes are simply square squeegee, and other shapes of squeegee are used for specific printing conditions. For example, hard squeegee performance is better than soft squeegee, but poor adaptability to organic glass products. With diagonal scraping, the printing edge is easily deformed (like a soft-squeegee).

There are three types of squeegee options for printing workers: square scraping (or right-angle scraping), various sloping and round scraping (horn scraping). The wide application of the square scraper can provide the maximum printing pressure, and the printing angle is determined according to the effective width. Diagonal scraping provides maximum flexibility, printing pressure is reduced, and the printing angle is smaller than the set angle. The round scraper is the least adaptable and provides the least printing pressure. The printing angle can be freely set (often the smallest angle). The above reasons will affect the amount of ink.

4. Blade:

The knife edge is an important part of completing the four functions of the squeegee. The sharpness of the squeegee is a factor in the initial control of the amount of ink. The sharp blade provides the smallest amount of ink and the finest image. A blunt and round knife edge increases the amount of ink underneath, and at the same time affects the color and line fineness.

When printing large areas and simple patterns with clear oil, the change in color and line fineness is not significant. When printing fine lines and four-color dots, with translucent (UV) and transparent ink, you will soon find out the deformation of the knife edge, and compare the first and last prints to determine when the squeegee should be Polished.