Which type of flame is preferably used to heat parts during brazing?

In brazing, the type of flame that is most commonly used to heat parts effectively is the oxyfuel flame, which is characterized by the combination of oxygen and a fuel gas (usually acetylene). This flame generates a high temperature that is necessary for melting the filler metal while keeping the base metals at their appropriate temperature without damaging them.

The oxyfuel flame can be adjusted to be neutral, carburizing, or reducing, but a neutral flame is preferred for brazing because it produces a balanced mixture of oxygen and acetylene, ensuring even heating and minimizing oxidation. However, when the focus is solely on the type of setup used, referring to oxyfuel highlights the specific combination of gases employed in brazing processes.

The other types of flames, like carburizing and reducing, add excess acetylene, which can introduce a carbon-rich environment that may affect the properties of the joint. This can lead to issues like incomplete fusion or undesirable reactions in the materials being joined, which is not ideal for brazing applications. Thus, the oxyfuel flame stands out as the most effective choice for performing brazing operations.