Precautions For Vacuum-pumping

- May 18, 2018-

▲ How to improve the pumping speed of the vacuum coating machine?

1. If it is the first time to use the vacuum coating machine, it can be heated while pumping (generally about 200°C) for 1-2 hours to remove water vapor and attachments.

2. The product must be completely dry before coating.

3. If the vacuum coating machine has been used for a long time and the vacuum pumping speed has slowed down, it is necessary to replace the machine's guard against plate and then heat it to bake.

4. If the pumping speed is suddenly becomes slow, please check the leak with the equipment, the key parts are: under the crucible and the thermocouple, the rotary machine, and the pump contact part.

5. Maintain and replace pump oil regularly.

▲ Evacuation procedure

First check the status of the vacuum chamber, under the vacuum or in the atmosphere, determine the two procedures to start the vacuum equipment: the first, operating procedures under the vacuum, the second, the operating procedures in the atmospheric state.

1. If the chamber is in a low vacuum state, the gate valve cannot be opened immediately to avoid backflow of vacuum oil.

The correct operation step is to open the faucet first, then open the mechanical pump, and turn on the vacuum gauge power supply. Observe that the vacuum gauge reading reaches 30Pa or so. Then turn on the molecular pump and the gate valve when the working frequency of the molecular pump reaches 50Hz.  

2. If the chamber is under the atmosphere, the first thing to do is leak detection, that is, close the chamber door and the vent valve. Then turn on the faucet, gate valve, mechanical pump, and vacuum gauge power supply. Observe that the vacuum gauge reading reaches about 30Pa, and then turn on the molecular pump.

3. When the molecular pump is working normally (the working frequency is stable at 450Hz), then press the starting button of the ionization gauge device to observe the vacuum degree.

4. When the vacuum reaches 10-4 - 10-5Pa, the ion pump can be turned on. At this time, the gate valve of the molecular pump is closed first, but the molecular pump is not be turn off until the voltage of the ion pump reaches 4000V (after the stable work of the ion pump), then turn off the molecular pump and the mechanical pump.

5. If it is not necessary to maintain the vacuum, turn off the vacuum gauge power first, and then only need to close the gate valve of the ion pump, do not turn off the ion pump, but keep the ion pump in working condition to maintain its internal environment.