Millwright Level 1 Practice Exam

What is the primary function of voltage in welding?

1. To increase metal hardness

2. To maintain the temperature of the welding arc

3. To start and maintain the arc, puddle fluidity, and flow

4. To control the depth of the penetration

The correct answer is: To start and maintain the arc, puddle fluidity, and flow

The primary function of voltage in welding is to start and maintain the arc, as well as to ensure proper puddle fluidity and flow. When welding, voltage creates the electrical potential difference necessary to establish the welding arc between the electrode and the workpiece. A stable arc is crucial for achieving a consistent heat input, which is essential for melting the base metal and filler material effectively. Once the arc is established, the voltage contributes to the energy delivered to the weld zone, influencing the fluidity of the molten weld puddle. This fluidity is vital for a good fusion between the base metal and the filler material. Additionally, the right voltage helps maintain the desired arc length, which directly affects weld quality. If the voltage is too low or too high, it can lead to an unstable arc, resulting in poor welds and defects. In summary, voltage plays a critical role in starting the welding process and maintaining the necessary conditions for effective weld formation through proper temperature control and melt pool characteristics.