Aluminum alloy vacuum brazing process

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Due to the characteristics and advantages of vacuum brazing, it is widely used. If the vacuum brazing process is selected for complex and precise aluminum alloy brazing, the vacuum brazing process can be formulated for the brazing of such parts before brazing. And inspection rules, but also need to analyze the influencing factors of brazing to ensure the quality of brazing. The main factors affecting the quality of vacuum brazing of aluminum alloys are brazing materials, vacuum brazing furnaces, brazing fixtures and brazing processes. These four aspects have the greatest impact on the quality of vacuum brazing of aluminum alloys.

In practice, for the brazing of precision parts, vacuum brazing is mostly used. The characteristics of vacuum brazing are that there is no need to remove flux after brazing, and the size of the welding becomes smaller, which can be Realize multiple welding seams, welding multiple parts at the same time, energy saving and environmental protection, etc. The so-called vacuum brazing is to debug the brazing materials and brazing components in advance using the brazing fixture, and then put the materials and components into the vacuum brazing furnace for heating, heat preservation, cooling and other operations, so as to achieve welding. the goal of.

Aluminum has high chemical activity and is prone to oxidation. If the pressure in the vacuum brazing furnace exceeds 6.0*10^Pa, the solder and base metal will gradually turn gray during the heating period, and the solder will not be effective. Wetting the base metal, so that welding cannot be achieved. Only when the pressure in the vacuum brazing furnace does not exceed 5.0*10Pa, the first 500C in the brazing furnace is slowly heated up, and the pressure is kept at 5.0*10^Pa during the heating process. Therefore, the pressure rise rate of the vacuum brazing furnace has become a key factor for the quality of aluminum alloy vacuum brazing. The pressure rise rate is to increase the pressure in the vacuum furnace to the pressure required for brazing. Usually the pressure rise rate of the vacuum brazing furnace is lower than 0.3PA° h’, which can weld aluminum alloys with higher quality, but when the pressure rise rate is large, even if the working pressure does not exceed 1.0* 10^Pa, The quality of the welding cannot be guaranteed. In addition, the leakage rate of the vacuum brazing furnace is also a key factor affecting the quality of brazing. The longer the leakage time is, the longer the oxidation reaction time of the aluminum alloy will be, and the worse the welding quality will be.

Aluminum alloy vacuum brazing process

The process flow of vacuum brazing of aluminum alloy is mainly: cutting of brazing material – removal of oxide film of brazing material – brazing material fixing + assembly – brazing inspection.

Aluminum alloy vacuum brazing insulation

Under normal circumstances, in the process of vacuum brazing heating of aluminum alloys, the temperature needs to be strictly controlled, so that the heating temperature is lower than the solidus temperature of the solder and higher than the liquidus temperature of the solder. The time of brazing heat preservation is usually about 2 minutes after the temperature of the workpiece reaches the liquidus temperature. If the heat preservation time is too short, the brazing seam will not be full, and if it is too long, the solder will be leaked. The temperature control of vacuum brazing needs to be determined according to the specific conditions of the parts and the furnace load. After brazing heat preservation, vacuum cooling is required to meet the deformation requirements of the part to determine the cooling rate value.

The RHVB-H high temperature vacuum brazing furnace produced by SIMUWU is a high-quality product for this type of brazing process. Good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum brazing process. With more than ten years of sales and manufacturing experience, it is exported to developed regions in Europe, America and Asia. It is a well-received vacuum furnace product.