What is vacuum Brazing?
Vacuum brazing refers to a welding process performed in a vacuum environment. In a vacuum, oxygen and other substances are excluded. After the solder is heated to a molten state, the materials to be welded are placed in a vacuum chamber for high-temperature welding technology. Brazing is a process in which solders such as tin-lead alloys are heated to a certain temperature, melted and wetted the metal surface to be welded, and then cooled and solidified to form a firm connection. A vacuum environment helps to improve the wettability and fluidity of the solder, making the welding more reliable and dense.
Process flow of vacuum brazing
Preparation work
Clean the welded parts, use appropriate cleaning agents to remove impurities such as oil and oxides on the surface of the parts, ensure that the surface is clean and smooth, and is conducive to the adhesion of the solder.
Assemble the parts to be welded according to the design requirements, and fix the position and gap.
Then start the vacuum system and pump the welding area to the required vacuum degree, generally below 10⁻³ Pa.
Heating and brazing
The welding area is heated by a heating device, usually using an infrared heater, an induction heater, etc. The heating speed should be moderate to avoid welding quality problems caused by too fast or too slow heating.
When the welding area reaches the temperature required for brazing (generally between 183℃-220℃, the melting point of tin-lead alloy), apply solder to the welding part. The solder will quickly melt and wet the metal surface to form a uniform welding layer.
According to the size and complexity of the welding part, control the welding time, generally between a few seconds and a few minutes. Too long time will lead to overheating and solder loss, and too short time may cause the welding to be weak.
Check after cooling
After the welding is completed, stop heating and let the welding area cool naturally. In a vacuum environment, the cooling speed is faster, which helps to maintain the quality of welding.
Check the welding part, including appearance inspection, welding strength test, etc. The appearance should be smooth, without defects such as pores and cracks; the welding strength should meet the design requirements and be verified by tests such as stretching and bending.
Matters needing attention during brazing operation
Vacuum control: Keep the vacuum degree of the welding area stable to avoid the influence of vacuum fluctuations on welding quality. During welding, the vacuum degree should be checked regularly to detect and solve problems in time.
Heating uniformity: The heating device can evenly heat the welding area to avoid local overheating or overcooling. Heating uniformity can be achieved by adjusting parameters such as heating power and heating time.
Solder selection: Select the appropriate solder according to the properties and requirements of the material to be welded. Different solders have different melting points, wettability and mechanical properties, and should be selected according to the specific situation.
Operation skills: Our operators should have certain welding skills and experience, and master the correct operation methods and techniques. For example, when applying solder, it should be even and appropriate to avoid solder accumulation or insufficient; during the welding process, keep a stable hand posture to avoid shaking and shaking.
Application areas of vacuum brazing
Aviation industry: used to manufacture honeycomb sandwich structure wall panels, jet engines and rocket missile device assemblies.
Electronic industry: brazing copper and stainless steel parts.
Automobile industry: generally manufacture precision parts and metal parts of complex shapes.
Vacuum brazing is a high-precision, high-quality welding technology. Jeek can provide you with vacuum brazing and welding processing services. We have professional knowledge and experience. If you have any needs for this project, please communicate with us in time.