Two Types of Printing Pressure Control Methods Before explaining “Zero Point,” let’s first discuss the control of squeegee pressure in screen printing.
Introduction
Micro-Tech’s “Zero Point” is slightly different from conventional screen printing machines. Checking the “Zero Point” during printing condition settings makes reproducing printing results easier.
This article will provide an easy-to-understand explanation of “Zero Point.” We hope it will serve as a useful reference for adjusting screen printing pressure.
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There are mainly two methods for controlling pressure:
- Downstop Method (conventional method commonly used)
- Air Balance Method (adopted by Micro-Tech)
Downstop Method
The Downstop Method, as the name suggests, determines the amount of squeegee descent beforehand and fixes the height of the descent point using a stopper.
In this method, the squeegee does not move up and down during printing. Therefore, the squeegee pressure is determined by the elasticity of the squeegee rubber.
While this method may be simple and easy to understand, it has a significant drawback: “squeegee flexes.“
Due to the deformation of the squeegee rubber depending on the push-in amount, not only the printing pressure but also the attack angle on the screen becomes unstable.
Consequently, stable printing results cannot be achieved, and skill is required for pressure control, leading to inferior reproducibility.
To address these issues, the Air Balance Method was introduced.
Air Balance Method
In the Air Balance Method, the squeegee pressure is controlled solely by air pressure. The role of air pressure in this method is twofold:
A. Lower the squeegee (squeegee pressure)
B. Raise the squeegee (back pressure) With these two pressures, printing pressure is controlled.
In particular, the presence of back pressure, which adds air pressure in the upward direction, is essential.
By applying back pressure, the weight of the squeegee unit is canceled out. With no influence from the weight of the squeegee unit, the squeegee can be controlled purely by “squeegee pressure.“
This method is very easy to control, significantly improving reproducibility and stability in printing.
The Essential “Zero Point” for the Air Balance Method
Now, let’s introduce the concept of “Zero Point.”
As mentioned earlier, the Air Balance Method allows the squeegee to be controlled purely by “squeegee pressure.” However, to achieve this, you must first perform “Zero Point Adjustment.”
What is “Zero Point Adjustment”?
“Zero Point Adjustment” involves:
“Maintaining the state with back pressure applied, gradually adding squeegee pressure until the descending squeegee begins to touch the screen and workpiece.”
In other words, Squeegee Pressure = Back Pressure + Screen Tension The point (zero point) is found. The downward pressure at the “Zero Point” is recorded as the “actual printing pressure zero” point.
Why does printing stabilize when “Zero Point” is set?
If pressure is increased from the “actual printing pressure zero” downward pressure, the increased pressure becomes the printing pressure. For example, if the downward pressure at the “actual printing pressure zero” is “0.12MPa,” increasing the pressure to “0.17MPa” results in applying “0.05MPa” of actual printing pressure.
By doing this, printing can be done under appropriate printing pressure conditions. Since no unnecessary printing pressure is applied, damage to the screen is also reduced.
The appropriate printing pressure condition that allows printing is called “actual printing pressure.” Since this “actual printing pressure” can be easily controlled, an improvement in reproducibility and stability in printing can be expected.
(To be continued)
Find out more!
Since understanding through text descriptions alone may be difficult, we have included an article on “Zero Point Adjustment” with photos here.
If you want to know the detailed work method, please refer to this article.
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If you want to know the detailed work method, please refer to this article.
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Translated by GPT