~ How far can you print with the attack angle of the squeegee? ~
Screen printing lovers! What is the attack angle of the squeegee when printing? The attack angle of the squeegee is the angle shown in Figure 1.
Generally, I think that it is most often around 70 degrees. The attack angle can be adjusted from 60° to 90° in Newlong Seimitsu Kogyo's screen printing machine. Now, how does this angle of attack affect printing? It is often said that a small angle of attack produces thicker inks and a larger angle of attack produces thinner prints.
By the way, How many tens of degrees can you print if you increase the angle of attack? When the attack angle is 90°, as you can see from Fig. 1, the flat surface of the tip of the squeegee hits the plate. When this happens, the frictional force between the squeegee and the plate suddenly increases. If you actually print in this state, the squeegee head drive will be overloaded and the printer will stop with an error signal.
To what degree can you print? The author used a squeegee with a rubber hardness of 90 degrees to print while changing the attack angle from 60 degrees to 88 degrees, and then measured and confirmed the film thickness of the printed ink. The reason why the hardness is 90 degrees is to keep the deflection of the rubber as small as possible and maintain an accurate angle of attack.
Fig. 2 shows the experimental results. We were able to print up to an attack angle of 88°. How about 89°? Due to the scale of the protractor used in the experiment, 89° could not be measured accurately and could not be experimented. Judging from the graph, printing seems to be quite difficult.
By the way, there is no change in the print film thickness when the angle of attack is 60° to 85°. Why? To confirm this, we investigated the relationship between the attack angle of 60° or less and the print film thickness. Since it is not possible to set an attack angle of less than 60° with a printing machine, I made an attack angle of less than 60° by polishing the tip of the squeegee and examined the print film thickness.
See Figure 3. In fact, changes in the print film thickness can be seen at a fairly low angle. It is true that the smaller the angle of attack, the thicker the printed film.
Then you may think that the squeegee of the printing press should lie down more. However, if you do this, the squeegee will bend greatly due to the pushing force of the squeegee head, and the side of the squeegee will hit the plate. If this happens, you cannot print.
Look closely at the Squeegee Rubber tip during printing, it should be a little bent.This deflection increases as the rubber hardness decreases. This deflection reduces the actual angle of attack where the squeegee is in contact with the plate. In other words, it is considered that the actual attack angle is controlled by the hardness of the squeegee and the adjustment of the attack angle of the printing machine.
You may need to change the way you think about angle of attack a little.
