For effective brazing, what should the distance between metals be to facilitate flow?

For effective brazing, having minimal clearance between the metals is essential to facilitate the flow of the filler material. This small gap allows the molten brazing alloy to penetrate and spread evenly through capillary action, which is the mechanism that draws the liquid filler into the joint.

When the clearance is minimal, the filler metal can easily move into the space and create a strong bond between the joined parts. If the clearance is too wide, the filler metal may not flow properly, resulting in inadequate or weak joints. On the other hand, no clearance is typically not practical, as it can prevent the filler material from entering the joint and properly wetting the surfaces. Identical clearance does not specifically address the need for minimized space to enhance flow either. Thus, having minimal clearance is the optimal condition for achieving a strong and effective brazed joint.