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Brazing with Air Blow Heater

Brazing with Air Blow Heater

There are many heating methods for brazing, and representative brazing methods include gas brazing, high-frequency induction brazing, resistance brazing, and arc brazing.
Brazing with the Air Blow Heater is not very common, so we experimented to what extent brazing is possible.

About Air Blow Heater

The Air Blow Heater is a heater with a simple structure. Compressed gas is supplied from an air compressor, and the gas is directly heated by a high-density heating element and discharged as hot air.
◎ The high-density heating element can be used to cleanly heat the supplied gas up to a maximum temperature of approximately 1050℃.
◎ Accurate temperature control can be performed using a thermocouple at the discharge port.
◎ Nitrogen can be directly heated, so it can be used for experiments on anaerobic microorganisms.
◎ Various metal fittings can be attached because the tip is internally threaded.
◎ Blows out hot air with high temperature and low humidity, which is advantageous in the drying field.

Brazing Procedure with Air Blow Heater

Acceptance InspectionMake sure it meets your quality standards.
PreprocessingRemoves stains such as anodized aluminum paint, rust, and oil
Flux ApplicationApply flux to the substrate. Not required when using phosphor-copper brazing for copper-to-copper brazing
Assembly of PartsBrazing joins two or more parts together. Pay attention to joint clearance
Brazing Filler Metal SupplyPlace the brazing filler material on top of the flux
Temperature ControlSet target temperature
Start HeatingInstall Air Blow Heater to raise the temperature of the entire joint
Flux ReliquefactionThe braze begins to melt at a temperature at which the water content of the flux re-liquefies after evaporation.
Melting of Brazing Filler MetalThe brazing filler material begins to melt, diffuse and bond.
CoolingHeating may soften the workpiece, so be sure to cool it.
Take OutCooling may be insufficient, so be careful not to burn yourself when removing.
Post-ProcessingRemove flux residue

Brazing of Aluminum with Air Blow Heater

The melting point of aluminum is 660℃, which is relatively low among metals, and when overheated, it exceeds the melting temperature of brazing and reaches the melting point of the base material (aluminum).
The melting temperature of hard brazing aluminum is 580℃, so the difference is only 80℃. Also, since it is a metal that is easily oxidized, it is important to control the temperature at an appropriate temperature.

The Air Blow Heater uses a thermocouple at the outlet to enable continuous temperature control, preventing overheating.

In addition, since a strong oxide film is formed on the surface of aluminum and aluminum alloys,
Using the flux as-is will not be able to remove them and may fail.
Therefore, it is necessary to remove the surface oxide film and dirt before brazing.

The flux used in aluminum brazing is highly corrosive and must be removed after brazing.
This treatment is especially important because incomplete removal of flux residue can cause corrosion and breakage of joints.
Furthermore, anti-corrosion treatment may be applied to increase the corrosion resistance of the brazed part.

The coefficient of thermal expansion of aluminum is about twice that of steel, and its thermal conductivity is about five times that of steel.
It is a material that is difficult to heat locally because it requires attention to thermal distortion due to heating.
Since the temperature of the hot air heater is lower than the temperature of the gas burner, the heating time will be longer.
The tact time can be shortened by using multiple units, increasing the flow rate, adding a preheating process, etc.

Also, even if a gas leak occurs, it is extremely safe as long as the supply gas is air.
If the supply gas is air, unlike gas, it is colorless, making it easier to check the brazing progress of the product.

Brazing Aluminum with Air Blow Heater

Brazing Aluminum and Cupper with Air Blow Heater

Application example

Various aluminum heat exchangers for automobiles

Examples of Major Brazing Failures

Examples of Major Brazing Failures

Air Blow Heater Products

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