Which factor is essential for the flow of filler metal during the brazing process?

The essential factor for the flow of filler metal during the brazing process relates directly to the size of the opening between the components being joined. When brazing, the filler metal must flow into the joint by capillary action, which is influenced heavily by the dimensions of the gap between the two parts. A smaller opening allows the liquid filler metal to be drawn in more effectively due to the surface tension and the cohesive forces at play, utilizing capillary action to ensure a strong bond.

In contrast, larger openings may fail to allow the filler metal to flow correctly due to reduced capillary action, which could lead to inadequate bonding and compromised joint integrity. The correct size of the opening is critical in achieving optimal flow and ensuring that the filler metal fully penetrates the joint to create a reliable and strong connection. The dynamics of capillary action thus underscore the importance of the opening's size in the brazing process.