Vacuum furnace maintenance method

The main reasons for the discoloration failure of vacuum furnace products include the following points
The discoloration failure of vacuum furnace products is mainly caused by oxidation, which may be due to insufficient vacuum, contamination or system leakage.
Studies have shown that maintaining the proper vacuum level and cleanliness can effectively reduce discoloration. Details: The vacuum requirements of different metals vary depending on the temperature. High vacuum is required for low temperature and lower vacuum can be used for high temperature.
Working principle of vacuum furnace
The vacuum furnace prevents oxidation by vacuuming to ensure that the workpiece is heated and brazed in an oxygen-free environment. The system includes mechanical pumps, Roots pumps and diffusion pumps to achieve and maintain the required vacuum level.
Causes of product workpiece discoloration failure
Discoloration is usually caused by the following factors: contamination in the workpiece or furnace, such as grease residue. Impure cooling nitrogen or leakage in the gas supply pipeline. Insufficient vacuum system exhaust efficiency. Inner or outer leakage of the vacuum chamber, such as poor valve sealing or cooling water pipe leakage.
Solution
Regularly check and maintain the vacuum system to ensure sealing and exhaust efficiency. Use a test ring test to determine whether the discoloration is caused by a vacuum system problem. Operate according to the latest standards and keep the furnace clean. Choose the right vacuum degree for different metals, for example, titanium and aluminum require a higher vacuum level.
The analysis and solution of discoloration failure of vacuum furnace products is a key issue in industrial production, especially in the aerospace, medical and semiconductor industries, where product quality directly affects equipment performance.
Equipment principle of vacuum furnace
The vacuum furnace achieves non-oxidative heating by creating an oxygen-free environment. Its structure includes a vacuum chamber, a pump system, a vacuum detection system, various control valves and a heat exchanger. The working process is as follows: Start the maintenance pump and open the maintenance valve to evacuate the front stage and pipeline of the diffusion pump.
When the vacuum pressure is lower than the specified value, the diffusion pump starts to heat. The mechanical pump starts to evacuate the vacuum chamber to a low vacuum, and the Roots pump starts after the conditions are met. When the diffusion pump reaches the allowable value for opening, close the roughing valve and the maintenance valve, open the front stage valve and the high vacuum valve, and continue to evacuate the high vacuum. After the vacuum degree reaches the heating condition, the temperature is controlled according to the process curve. After cooling is completed, fill with nitrogen and start the cooling fan. When the temperature is lower than 100°C, the furnace cover can be opened to remove the workpiece.
Analysis of the cause of discoloration of product workpieces
The workpiece is not cleaned or the vacuum chamber is polluted: contaminants such as grease evaporate or decompose in the vacuum, causing oxidation. Impure cooling nitrogen or pipeline leakage: polluted nitrogen or leaking point inhales air, increasing the oxygen partial pressure. Insufficient exhaust efficiency: the ultimate vacuum degree is not reached or the gas is released during heating, causing oxidation. Leakage in the vacuum chamber: internal leakage (such as the valve is not closed tightly) or external leakage (such as poor sealing of the furnace door).
Troubleshooting method
It is recommended to use the elimination method to determine the fault: detect the change in the ultimate vacuum degree. If the change is large, it is judged to be a vacuum system problem and leak detection is performed. Test the pressure rise rate after high-temperature furnace baking to determine the cause of discoloration. Load the product and heat it according to the process curve. If the product does not change color, the vacuum system problem can be ruled out. Check the water content, oxygen content, and dew point temperature of the cooling nitrogen.

VACUUM FURNACE