How is current typically controlled in spot welding?

How is current typically controlled in spot welding?

• A. By varying electrode material.
• B. Major adjustment by tap switch on the primary transformer; fine adjustment by electronic heat control.
• C. By changing the welding speed.
• D. By adjusting the workpiece thickness.

Answer: (B)

In spot welding, the heat in the weld comes from the current flowing through the workpieces, so the ability to set and fine-tune that current is the key to controlling the weld. The primary way this current is controlled is by selecting a tap on the welding transformer, which changes the turns ratio and thus the secondary current delivered to the workpieces. That’s the major adjustment. For finer control, electronic heat control trims the current (and sometimes the pulse duration), giving precise heat input to achieve a consistent weld. Electrode material generally influences contact resistance and wear, not the method of setting the current. Welding speed affects how long the current is applied and the heat input, but it does not establish the current level itself. Workpiece thickness dictates the needed current for a good weld, but the actual control mechanism remains the transformer taps plus electronic regulation.

In spot welding, the heat in the weld comes from the current flowing through the workpieces, so the ability to set and fine-tune that current is the key to controlling the weld. The primary way this current is controlled is by selecting a tap on the welding transformer, which changes the turns ratio and thus the secondary current delivered to the workpieces. That’s the major adjustment. For finer control, electronic heat control trims the current (and sometimes the pulse duration), giving precise heat input to achieve a consistent weld.

Electrode material generally influences contact resistance and wear, not the method of setting the current. Welding speed affects how long the current is applied and the heat input, but it does not establish the current level itself. Workpiece thickness dictates the needed current for a good weld, but the actual control mechanism remains the transformer taps plus electronic regulation.