Brazing Gap Capillary Effect
The brazing gap capillary action is the basic physical principle for the transport of filler metal in narrow joint gaps through adhesion and cohesion forces.
Physicochemical Mechanism of Action
Capillary action in the brazing gap is based on the adhesive forces between the liquid filler metal and the walls of the narrow joint gap, as well as the cohesive forces within the filler metal. These forces cause the filler metal to be drawn toward the smallest surface (the gap).
Metallurgical Relevance & Welding Risks
Capillary action affects the distribution of filler metal within the joint gap. Excessive capillary action can cause the filler metal to be drawn too strongly into the gap and become trapped, leading to a poor joint or even a gap splinter. This can impair the strength of the weld.
Workshop Practice & Instructions
To ensure optimal filler metal distribution and a good weld, it is important to keep the joint gap as large as possible. This can be achieved by choosing the right gap dimension and proper welding parameters. An excessively narrow gap should be avoided, as this intensifies capillary action and compromises the joint.