Vacuum brazing means that the workpiece is heated in a vacuum chamber and is mainly used for the welding of products requiring high-quality and easily oxidized materials. Safe operation steps of vacuum brazing furnaces are numerous and require caution. Today, vacuum brazing plant Sanqian will introduce the process of vacuum brazing to you.
Safe operation steps of vacuum brazing furnace
1. The electrical cabinet sends electricity, water, and ventilation.
2. Turn on the maintenance pump, and after 2 minutes, press the start switch of the diffusion pump to heat the diffusion pump. Observe whether the current of the diffusion pump is normal, and preheat the diffusion pump for about 1-1.5 hours (note: keep the air outlet of the pump from being blocked)
3. In the preheating device, the workpiece loading and unloading work in the furnace can be carried out. After loading and unloading, the furnace door should be locked in place (remember: no other items should be left in the furnace except the workpiece)
4. When the preheating time of the diffusion pump is up, turn on the two mechanical pumps, and open the pre-pumping valve after 30 seconds to pump the vacuum furnace. When the vacuum reaches 1-2 kPa, turn on the Roots pump. When the pumping reaches 7-8 Pa, close the pre-extraction valve, open the front-stage valve, and then open the high vacuum valve to pump a high vacuum to the furnace body.
5. When the heating power-on prompt light on the control cabinet is on, turn the heating power knob to the ON position, and the furnace body can be heated.
6. When the heating process curve is completed, turn off the furnace heating. Wait for the furnace body to cool down naturally. If rapid cooling is required, when the temperature drops to a certain value (according to the requirements of the process of vacuum brazing curve), close the high valve, close the front valve, close the Roots pump, and close the two mechanical pumps.
7. Open the backfill valve now, and then open the pressure equalizing valve. When the backfilling reaches the set value of the backfilling pressure, the backfilling valve will automatically close; when the equalizing pressure reaches the setpoint of the equalizing pressure, the equalizing valve will automatically close.
8. Open the inlet and outlet valves, when the inlet and outlet valves are fully opened (the indicator light on the panel is on), turn on the knob of the forced cooling fan to perform forced cooling. When cooling to the position required by the process, stop the forced cooling fan, and after the forced cooling fan stops completely (about 2 minutes), close the air inlet and outlet valves, close the backfill valve, close the pressure equalizing valve, open the air breaking valve, and the furnace body Fill with air.
9. Open the furnace door and remove the weldment. A cycle process ends.
The process of vacuum brazing
1. After the workpiece enters the furnace, close the furnace door, first start the mechanical vacuum pump, open the bypass valve, and then start the roots pump after vacuuming for about 10 minutes, open the main circuit valve to start the diffusion pump, and the diffusion pump works for 80-90 minutes. During a period of time, you can pre-heat below 360 degrees while vacuuming, and after the diffusion pump works, the vacuum degree reaches 10-2Pa or more and continue to heat until the end of brazing (Vacuum brazing plant Sanqian reminds you: vacuum during heating There is a certain drop in the degree); it needs to be paused, and the heating will continue until the vacuum degree is restored.
2. The heating rate of the furnace temperature should be slow before 520 °C to avoid a large temperature difference between the inside and outside. According to the temperature difference and the size of the workpiece, the heat preservation section can be accelerated or increased in the middle. The purpose is to minimize the temperature difference between the inside and outside and improve the vacuum degree. , generally, small workpieces can heat up faster;
3. When the central temperature of the workpiece reaches or is close to the brazing temperature, the size of the workpiece can be advanced or delayed depending on the size of the workpiece. When the brazing temperature is reached, the heating should be stopped so that the workpiece can be brazed at a constant temperature at the brazing temperature;
4. The temperature of the brazing workpiece is 575-605 degrees for the heat exchanger, and the heat dissipation strip is 560-605 degrees. For large workpieces, the core temperature should be controlled, and the brazing time should be determined according to the size of the workpiece;
5. After the workpiece is released from the furnace, it is naturally cooled in the air. At this time, it is necessary to check whether the brazing seam is full, check the brazing quality and external dimensions and other items, and then stamp the brazing stamp on the workpiece (including the brazing date, or number) ;
6. The parameters of the brazing process should be recorded in detail, and the records should be included in the product quality file for reference when analyzing and researching product quality problems.
Vacuum brazing plant Sanqian has been focusing on vacuum brazing for many years and is responsible for the production, manufacture, and sale of various heat sinks and water cooling plates. The above is the Safe operation steps of vacuum brazing furnace and the process of vacuum brazing shared today. If you are interested in this, please contact us!
