SAW Equipment Setup & Operation 3 — Questions and Answers
Question 1: What effect does increasing travel speed have on a SAW weld bead (all other parameters held constant)?
- Wider, flatter bead with more dilution
- Narrower, higher-crowned bead with less penetration (Correct answer)
- Same bead width but deeper penetration
- Increased heat input and wider HAZ
Correct answer: Narrower, higher-crowned bead with less penetration
Higher travel speed reduces the time the arc dwells on a given spot, producing a narrower, more crowned bead with reduced penetration and lower heat input.
Question 2: In a SAW power source, what does a 'constant voltage' (CV) characteristic mean for operation?
- The machine maintains a fixed wire feed speed regardless of arc conditions
- The output voltage remains nearly constant while current varies to maintain arc length (Correct answer)
- Current is held constant while voltage fluctuates to control heat
- The duty cycle is unlimited at any amperage setting
Correct answer: The output voltage remains nearly constant while current varies to maintain arc length
A CV power source self-regulates by varying current output to maintain the preset voltage, which keeps arc length stable when wire feed speed is fixed.
Question 3: Which of the following correctly describes the role of 'run-on' and 'run-off' tabs in SAW?
- They preheat the base metal before welding starts
- They allow the arc to start and stop off the main workpiece, preventing crater defects at weld ends (Correct answer)
- They support the flux dam at the joint edges
- They provide electrical ground for the workpiece
Correct answer: They allow the arc to start and stop off the main workpiece, preventing crater defects at weld ends
Run-on and run-off tabs extend the joint beyond the base metal so weld initiation and termination defects (cracking, porosity) occur on disposable material.
Question 4: A SAW operator notices that the arc is wandering erratically during welding. The most likely cause is:
- Excessive flux depth
- Worn or misaligned contact tip causing poor current transfer (Correct answer)
- Too high a travel speed
- Incorrect flux basicity index
Correct answer: Worn or misaligned contact tip causing poor current transfer
A worn or misaligned contact tip creates inconsistent electrical contact, causing the arc to wander as current path varies.
Question 5: What is the recommended minimum flux coverage depth during SAW to ensure adequate shielding?
- 6 mm (¼ in)
- 13–38 mm (½–1½ in) (Correct answer)
- 50 mm (2 in)
- 75 mm (3 in)
Correct answer: 13–38 mm (½–1½ in)
Flux coverage of approximately 13–38 mm (½–1½ in) is generally recommended to fully bury the arc and prevent flash-through while allowing proper slag formation.
Question 6: When welding with a SAW system on a rotating positioner, the joint should ideally be positioned at:
- Exactly the top (12 o'clock) position
- Slightly in front of the top position in the direction of rotation so the weld pool solidifies flat (Correct answer)
- At the 3 o'clock position for horizontal welding
- At the lowest point to allow gravity-aided penetration
Correct answer: Slightly in front of the top position in the direction of rotation so the weld pool solidifies flat
Positioning the joint slightly before the apex (in the direction of rotation) ensures the molten weld pool travels to the top and solidifies in a flat position without running.
Question 7: Which SAW wire electrode diameter is most appropriate for high-deposition, heavy structural applications requiring currents above 800 A?
- 1.6 mm (1/16 in)
- 2.4 mm (3/32 in)
- 3.2 mm (1/8 in)
- 4.0 mm (5/32 in) (Correct answer)
Correct answer: 4.0 mm (5/32 in)
Larger diameter electrodes (4.0 mm / 5/32 in) are used for very high current applications because they have greater current-carrying capacity and produce high deposition rates.
SAW Equipment Setup & Operation 3
What effect does increasing travel speed have on a SAW weld bead (all other parameters held constant)?