Aluminum chemical activity is active and easy to get oxidation.While pressure ≥ 6 × 10-3 Pa, in the heating process, the base metal and solder is oxidized into gray.The solder can not wet the base metal. Only in the pressure ≤ 5 × 10 – 3 Pa, and slowly heated it at 500 ℃ , and make the heat preservation at 450 ℃ for 30 mins to ensure that the pressure in the process of maintaining at ≤ 5 × 10-3 Pa,the it can achieve aluminium brazing.
Vacuum brazing furnace pressure rise rate is an important indicator to ensure the quality of brazing.The pressure rise rate is the vacuum furnace pressure back to the working pressure,stop the vacuum system, the unit time of the furnace pressure recovery rate, also known as the leakage rate, which reflects the leakage performance of the brazing furnace.If operator wants to weld the higher quality aluminum alloy parts, the pressure pressure rise rate should be < 0.3Pa·h – 1.
In the temperature range of 500 ℃ ~ 600 ℃, the heating rate has an important effect on the welding quality. The heating rate is low. In the vacuum environment, the low melting point of the solder is rapidly volatilized, leaving the high melting point element and not forming the flow. After the end of the cooling rate is also very important, too slow cooling, equivalent to extend the holding time, will produce diffuse, leakage welding, erosion and other defects.
Vacuum brazing furnace should be equipped with air-cooling system,which can quickly cool. In the premise to ensure the accuracy of parts under the premise of , then use fastest cooling. Aluminum alloy brazing requires the high furnace temperature control accuracy,temperature uniformity requirements are high, range of ± 5 ℃ can meet the small parts of the vacuum brazing, now uniformity temperature control accuracy ± 1 ℃ and ± 3 ℃ furnace temperature ,by which can braze high quality parts.
Tags: Vacuum aluminum brazing furnace,solder ,temperature uniformity
Edited by : Jessica Wu