Tools & Equipment Operation Flashcards

What is the purpose of the ground clamp in an arc welding circuit?

Answer: To complete the electrical circuit by connecting the workpiece to the power source's work terminal

The work clamp (ground clamp) provides the return path for welding current from the workpiece back to the power source.

Which lens shade number is generally recommended for GMAW (MIG) welding at 150–250 amperes?

Answer: Shade 10

AWS Z49.1 recommends shade 10 for GMAW at 150–250 amps to protect the eyes from arc radiation at that amperage range.

What happens if MIG welding contact tips become worn or oversized?

Answer: The wire develops poor electrical contact, causing erratic arc starts and inconsistent bead quality

An enlarged contact tip bore creates electrical resistance variations, leading to arc instability and poor fusion.

On a TIG welding machine, the high-frequency (HF) start function is used to:

Answer: Initiate the arc without touching the tungsten electrode to the base metal

HF start ionizes the shielding gas gap, allowing arc ignition without contaminating the tungsten by touching the workpiece.

What does the term 'open circuit voltage' (OCV) refer to on a welding machine?

Answer: The voltage at the output terminals when no arc is established and no current is flowing

OCV is the no-load output voltage; it must be high enough to establish the arc but drops significantly once welding current flows.

A wire brush used to clean a weld bead after SMAW should be made of:

Answer: Carbon steel bristles compatible with the base metal being welded

Steel wire brushes on carbon steel remove slag and spatter without introducing foreign metals that could cause contamination.

The amperage output of a welding machine should be checked with:

Answer: A calibrated clamp-on ammeter placed around the welding cable

A clamp-on ammeter measures DC or AC current without breaking the circuit, giving an accurate reading of actual welding amperage.