-Pitfalls of plate separation conditions-
Various conditions for screen printing include "printing speed", "printing pressure (squeegee pushing amount)" and "clearance". Some of these conditions are a bit tricky. That is the condition of "version separation".
At our company, we call the requirements for plate release as "detachment" as a condition of "mechanism that supports plate release", so hereafter we will explain it as "detachment".
At our company, we call the requirements for plate release as "detachment" as a condition of "mechanism that supports plate release", so hereafter we will explain it as "detachment".
Both our printing machines and other companies' printing machines are expressed as "detachment condition XX mm". For example, let's say the take-off condition for a product is 3.0 mm. And the printer used for the prototype was a model called LS-A from N company.However, we decided to use M company's LS-B for the printing press used for mass production, and set the condition of 3.0 mm at the time of trial production to LS-B.
Now, can we print in the same way as the prototype?
It doesn't really work that way. This is because the attachment/detachment mechanism differs depending on the printing machine. The take-off motion means that the screen plate is pulled up in conjunction with the stroke of the squeegee to assist the plate separation. In other words, the clearance (the gap between the screen plate and the workpiece) is increased in conjunction with the stroke of the squeegee.
Since the center of the screen plate has ink on it, the weight of the plate bends the plate and reduces the clearance. For this reason, when the squeegee is in the center of the plate during printing, plate separation becomes worse.
Especially when printing with high-viscosity ink, this tendency becomes stronger because the viscosity of the ink is high and the adhesion between the screen plate and the work is strong. If you try to improve stencil release by using only clearance without using detachment, you will end up with more clearance than necessary at both ends of the screen stencil. If the clearance is increased, the screen plate will be stretched, resulting in poor printing accuracy. To avoid this, the attachment/detachment mechanism is designed to provide a large clearance according to the position of the squeegee during printing.
However, since the take-off mechanism also increases the clearance, excessive take-off and take-off will still result in poor printing accuracy.
Since the center of the screen plate has ink on it, the weight of the plate bends the plate and reduces the clearance. For this reason, when the squeegee is in the center of the plate during printing, plate separation becomes worse.
Especially when printing with high-viscosity ink, this tendency becomes stronger because the viscosity of the ink is high and the adhesion between the screen plate and the work is strong. If you try to improve stencil release by using only clearance without using detachment, you will end up with more clearance than necessary at both ends of the screen stencil. If the clearance is increased, the screen plate will be stretched, resulting in poor printing accuracy. To avoid this, the attachment/detachment mechanism is designed to provide a large clearance according to the position of the squeegee during printing.
However, since the take-off mechanism also increases the clearance, excessive take-off and take-off will still result in poor printing accuracy.
Well, this is the main subject.
The aforementioned 3.0 mm release/attachment generally indicates the maximum lifting amount of the screen stencil when the squeegee reaches the stroke end. For example, 3.0mm takeoff and landing means that the screen plate is lifted by 3.0mm when the stroke of the squeegee is completed. Here's the problem. What is the actual take-off and take-off movement of the printing press when the take-off amount is set to 3.0 mm in the press condition settings?
The aforementioned 3.0 mm release/attachment generally indicates the maximum lifting amount of the screen stencil when the squeegee reaches the stroke end. For example, 3.0mm takeoff and landing means that the screen plate is lifted by 3.0mm when the stroke of the squeegee is completed. Here's the problem. What is the actual take-off and take-off movement of the printing press when the take-off amount is set to 3.0 mm in the press condition settings?
Here's an example.
During take-off and landing, one side of the screen plate is pulled up, so there is always a fulcrum for pulling up. Suppose there is a printing press with different fulcrum positions in diagrams A and B. For both printing machines, if the take-off condition is set to 3.0mm, one side of the screen will be lifted by 3.0mm when the squeegee stroke is completed. Compare diagrams A and B. It can be seen that the clearance at the position where the squeegee stroke ends (the position where the squeegee stops) is large when the fulcrum of take-off and landing is farther from the screen plate. In other words, the elongation of the screen plate increases, and the printing accuracy of the printing machine shown in Figure A decreases. Normally, in the case of a printing machine like that shown in Figure A, it is necessary to set the take-off and landing amount to be smaller than that of the printing machine shown in Figure B.
During take-off and landing, one side of the screen plate is pulled up, so there is always a fulcrum for pulling up. Suppose there is a printing press with different fulcrum positions in diagrams A and B. For both printing machines, if the take-off condition is set to 3.0mm, one side of the screen will be lifted by 3.0mm when the squeegee stroke is completed. Compare diagrams A and B. It can be seen that the clearance at the position where the squeegee stroke ends (the position where the squeegee stops) is large when the fulcrum of take-off and landing is farther from the screen plate. In other words, the elongation of the screen plate increases, and the printing accuracy of the printing machine shown in Figure A decreases. Normally, in the case of a printing machine like that shown in Figure A, it is necessary to set the take-off and landing amount to be smaller than that of the printing machine shown in Figure B.
As for the take-off device, we also have take-off and take-off mechanisms with different specifications. Also, depending on the line configuration of the equipment, the standard printer and the take-off mechanism may be changed. Some other companies' presses look similar to ours. Care must be taken when using printing machines from different manufacturers for prototyping and mass production.
After setting the take-off conditions, it is necessary to check what kind of structure the take-off device of the printing machine you are using and how it will operate when the take-off conditions are set.
After setting the take-off conditions, it is necessary to check what kind of structure the take-off device of the printing machine you are using and how it will operate when the take-off conditions are set.
