Vacuum coating machine design should pay attention to details

In order to ensure that the vacuum coating machine has a good sealing performance, it is necessary to cut off the cause of the possible leak at the source. Therefore, it is far from enough to find the location of the leak after the equipment is installed and to block the channel of the leak. It is necessary to carry out vacuum leak detection when setting up the design of the vacuum coating machine.

Some vacuum coating precautions that Dingyi Technology needs to pick up leaks in the design process:

1,
According to the process requirements of the equipment, determine the total maximum allowable leak rate of the vacuum coating machine, and determine the maximum allowable leak rate of each component based on this total leak rate.

2,
According to the maximum allowable leak rate of the equipment and other indicators, the leak detection method to be adopted is preliminarily determined at the design stage, and it is taken as one of the basic principles to guide the commissioning and acceptance.

3.
According to the maximum allowable leakage rate index of the equipment or components, determine the sealing, connection mode and overall processing accuracy of the equipment, and which dynamic sealing form can meet the requirements. For example, the flange adopts metal seal or rubber seal.

4.
When designing the structural strength of the container, consider the pressure resistance and structural strength of the inspected piece if the pressure method is used for leak detection.

5.
When selecting structural materials for parts, consider whether materials that may be corroded by the working medium and leaking gas may be damaged.

6.
During structural design, necessary spare interfaces for leak detection instruments should be left on the container or system for use in leak detection during equipment assembly and commissioning. Especially for large and complex pipeline systems, it is usually necessary to adopt a segmented leak detection method. Therefore, segmental isolation valves should be installed on the pipeline, and a leak detection instrument interface should be reserved on each isolation segment.

7.
When designing the structure of parts, try to avoid adopting design schemes that may interfere with the leak detection work. For example, the screw hole in the vacuum chamber cannot be in the form of a blind hole, because the gas in the remaining space inside the screw hole can only escape through the thread gap after the screw is installed, forming a virtual leak. Thereby prolonging the pumping time of the system and interfering with the normal operation of leak detection. As shown in the figure, the structure that should not appear in the vacuum leak detection.

8,
Similar to this, continuous double-sided welds and multi-layer sealing ring structures are not allowed in the structural design, because this will form a "parasitic volume" in the middle and the gas in the gas will form a virtual leak; and when the inner and outer double-sided welds or When the sealing ring leaks at the same time, the "parasitic volume" makes the response time for the leaking gas to pass through the double-layer weld seam too long, making it impossible to detect the leak normally.

9,
When designing the welded structure, minimize the number of welds that cannot be leak-tested after assembly.

        The vacuum coating machine leak detection work needs to be carried out at any time in the design, manufacture, commissioning, and use of all relevant links. However, in order to reduce the aggravation of the later leak detection work, it must be in the source design process, and attention should be paid to the leak detection work to ensure the vacuum coating machine. The reduction of leak-picking links.