AWS Certified Welding Inspector — FundamentalsWelding ProcessesMedium
A CWI is inspecting a Flux Cored Arc Welding (FCAW) operation using a self-shielded (FCAW-S) electrode. The welder is experiencing significant wormholes and excessive smoke. Which of the following is the most likely cause of these defects?
- AToo low wire feed speed.
- BExcessive voltage.
- CInsufficient travel speed.
- DImproper electrode stick-out.
Show answer & explanationAnswer & explanation
Correct answer: D. Improper electrode stick-out.
Excessive electrode stick-out in FCAW-S can lead to an unstable arc, insufficient shielding from the flux, and overheating of the wire, resulting in defects like wormholes and excessive smoke.
Why the other options are wrong
- A. Too low wire feed speed (without adjusting voltage) would result in a longer arc, reduced penetration, and potentially an unstable arc, but less likely the primary cause of wormholes/smoke compared to stick-out.
- B. Excessive voltage (without adjusting WFS) can cause a wide, flat bead and increased spatter, but wormholes and excessive smoke are more strongly linked to shielding issues.
- C. Insufficient travel speed typically leads to excessive weld metal, poor bead shape, and potentially burn-through, but not primarily wormholes and excessive smoke in FCAW-S.
FCAW-S Stick-out Issues
In Self-Shielded Flux Cored Arc Welding (FCAW-S), proper electrode stick-out is crucial for effective shielding and arc stability. Excessive stick-out can cause defects.
- Excessive stick-out reduces current density.
- Affects flux decomposition and gas shielding.
- Can lead to wormholes and porosity.
- Increases smoke and fumes.
Memory trick: Stick-out too long, shielding's all wrong, smoke and holes will come along.