Millwright Level 1 Practice Exam

What is the key characteristic of brazing?

1. Melting the base metal

2. Filler metal is spread through capillary attraction

3. Using only solid metal rods

4. Welding without filler metal

The correct answer is: Filler metal is spread through capillary attraction

Brazing is defined by the process of joining two or more metals by melting a filler metal that has a lower melting point than that of the base metals. A key characteristic of brazing is the use of capillary action to spread the filler metal into the joint between the base metals. This capillary attraction allows the molten filler metal to flow into the tight spaces of the joint, creating a strong bond once it cools and solidifies. This process occurs without the need to melt the base metals, which differentiates brazing from other joining methods like welding. Instead, the base metals remain solid, which helps maintain their structural integrity and properties. The specific temperature range where brazing operates—typically above 450°C (about 840°F)—is designed to ensure that the base metals do not melt, but the filler metal does. By understanding capillary attraction's role in the brazing process, one can appreciate its importance in achieving successful joints in various industrial applications.