Brazing flux

I. The Function of Flux：

Flux is an indispensable 'unsung hero' in brazing. It is like a 'cleaner + bodyguard' for metal connections, with three core missions:

1.Powerful Decontamination: After melting, it dissolves the oxide film on the surface of the base metal (such as rust and patina on copper), enabling the brazing filler metal to have 'intimate contact' with the metal.

2.Isolation and Protection: It covers the metal surface to prevent oxygen from 'causing damage' at high temperatures and avoids secondary oxidation.

3.Paving the Way: It reduces the surface tension of the liquid brazing filler metal. Just like a 'lubricant', it helps the brazing filler metal flow evenly and fill the gaps.

II. Types of Flux and Their Applicable Scenarios：

According to the composition and application, fluxes can be divided into four categories, which are suitable for different scene requirements:

III. How to Select Flux?

IV. The Forms of Flux and Its Usage Techniques：

-Paste - like: It can be accurately applied and is suitable for complex joints (such as threads and grooves).

-Powder: It is brushed after being mixed with ethanol, which is economical and practical.

-Pre - coated: The brazing flux is pre - coated on the surface of the filler metal to simplify the operation (such as flux - cored wire).

-Spray - type: It can quickly cover large - area welds on automated production lines.

V. Precautions for Using Flux：

-Safety first: Fluoride brazing flux will release harmful gases when heated. It is necessary to ensure good ventilation and wear protective masks!

-Appropriate usage amount: If the amount is too small, the oxide film cannot be cleaned thoroughly, and if it is too much, it is likely to leave residues that cause corrosion (the recommended thickness is 0.1–0.3mm).

-Clean in a timely manner: Use hot water or special cleaning agents to remove the residues after welding (sandblasting can be used for hard residues).

-Store in a sealed way: Borax is prone to absorbing moisture and caking, and fluoride brazing flux needs to be protected from light and moisture.

VI. Summary in One Sentence：

Flux is the 'unsung hero' behind the success of brazing - it clears obstacles, ensures purity, and aids in the flow. By choosing the right type, metal connections can be achieved with twice the result for half the effort!