Define dwell time in a brazing cycle.

• A. The time the joint is cooled after brazing.
• B. The time the joint is applied with flux.
• C. The time the joint is heated in the furnace exclusively.
• D. The time the joint is maintained at brazing temperature for complete flow and bonding.

Answer: (D)

In brazing, the key step is when the filler metal melts and can wet and flow into the joint to form a bond. Dwell time is the period during which the joint is held at the brazing temperature after the filler has melted, allowing the liquid metal to flow by capillary action and establish a complete bond. If you don’t keep the assembly at temperature long enough, you can get incomplete fill and weak bonding. If you keep it too long, you risk oxidation or unnecessary cycle time. Flux application is a preparation step that helps wetting, and heating isn’t enough by itself—you need that sustained hold at brazing temperature for proper flow and bonding.