Final answer:
Capillary action distinguishes brazing from braze welding, as brazing relies on the adhesion and cohesive forces of the molten filler metal being drawn into a joint through capillary action, whereas braze welding does not primarily rely on these forces and is similar to traditional welding.
Step-by-step explanation:
Understanding capillary action is critical when differentiating brazing from braze welding. Brazing involves the flow of filler metal into the joint by capillary action. This process depends on the correct clearance between the parts being joined so that the molten filler metal, when heated, is drawn into the joint through capillary action. The adhesion of the molten metal to the solid surfaces in conjunction with its own cohesion allows the filler metal to be distributed throughout the joint.
In contrast, braze welding does not primarily rely on capillary action but is more akin to traditional welding; the filler metal is deposited on top and is not distributed throughout the joint by capillary forces. Brazing requires precise control of the gap and clearance to allow capillary action to effectively distribute the filler metal, which makes it distinct from the more weld-like characteristics of braze welding.
The adhesive and cohesive forces are fundamental in facilitating this process. A strong adhesion between the molten filler metal and the metal surfaces of the workpiece promotes capillary action, while cohesive forces within the filler metal influence its flow characteristics and surface tension, playing a role in the formation of the meniscus during the process.