It is necessary to carefully read the welding instructions. If there is cadmium in the welding material, it is necessary to ensure good ventilation in the welding workplace, and ensure that the smoke is not inhaled or in contact with eyes and skin. Cadmium fume is highly toxic.
The components to be brazed must be carefully cleaned and firmly assembled, and the dust on the outer surface must be removed. The outer surface must be cleaned with high-quality stainless steel wire wool, and the inner surface must be cleaned with a stainless steel wire brush or stainless steel cotton roll into a roll.
There must be sufficient contact area between components, such as inserting copper tubes into (rather than driving) joint fittings. The contact area also does not need to be too large (approximately 3 times the minimum cross-section).
It is important to ensure that the flux does not enter the system during welding because it is difficult to remove it after welding is completed. Do not use excessive flux, but apply it to the surface of the inserted workpiece. In this way, excessive flux will remain on the outside of the tube.
All air in the welded pipe must be discharged, and carbon dioxide or hydrogen can be filled to remove the air. If there is oil in the pipe or workpiece, it will evaporate into oil vapor when heated by the welding gun, and the oil vapor will explode when it encounters air. If non combustible gases such as carbon dioxide or oxygen are used, such disasters can be avoided.
Warning: Do not use refrigerant, oxygen, and compressed air.
Care must be taken when heating the joint. During the heating process, the form of the flux can well display the temperature of the joint.
1. During welding, always keep the flame covering the joint to prevent air from entering.
2. The flux will be dried and the moisture will evaporate at 212 "F (100 ℃), after which the flux will become milky white.".
3. The flux will blister at 600 "F (316 ° C).
4. At 800 "F (427 ℃), the flux becomes a paste.".
5. At 1100 "F (593 ° C), the flux becomes fluid. This point is just near the brazing temperature.".
The solder alloy melts at 1120 "F (604 ° C) and flows at 1145" F (618 ° C). The welding gun used for brazing is several sizes larger than the welding gun used for low-temperature welding. It should be noted that both workpieces to be welded must be heated with a welding gun.
Whether the temperature is appropriate can be seen from the color of the secondary flame. When the temperature reaches the brazing temperature, the flame begins to shade. When the silver welding temperature is reached, a clean flux and a green flame indicate that the temperature is appropriate.
When copper pipes and steel pipes are welded to each other, first heat the copper pipes (because the copper pipes transfer heat quickly and require more heat). Add some combustion aid to the solder rod to help it flow.
When cutting off the capillary tube, first use a triangular file to make a circle of notches on the tube, and then repeatedly bend (small bends) back and forth to break the tube, so that the inner diameter of the tube remains unchanged. Using a pipe cutter will reduce the inside diameter of the pipe.
Do not clean the end of the tubing, as solder may clog or partially clog the capillary tube bore (inner diameter).
During the brazing process, the welding gun should not always be stopped at a single point, but constantly move back and forth across the entire welding area. Don't just heat a little, but keep the welding gun moving. Many maintenance personnel like to use a welding gun for a zigzag movement. It is recommended to use a large welding gun. This allows for a gentle flame and large heat without overpressure or "blowing". It is best to have a slight plume on the inner conical flame.
Whether it's brazing on a refrigerator or other aspects of brazing, these are the same principles, so there is no special emphasis on the brazing technology of a refrigerator.
Daheda Machinery specializes in the production and sales of water chillers | low-temperature water chillers | industrial water chillers | refrigerators | water-cooled water chillers | air-cooled water chillers | screw type water chillers | mold temperature machines | mold temperature controllers | mold thermostats | high-temperature mold temperature machines | plastic crushers | blenders | hopper dryers | suction machines | mold racks