AWS Certified Welding Inspector — FundamentalsWelding ProcessesMedium
A CWI is inspecting a Flux Cored Arc Welding (FCAW) operation on a heavy structural steel beam. The welder is using an FCAW-G electrode. The inspector notices inconsistent bead width and excessive spatter. Upon investigation, the CWI observes that the contact tip-to-work distance (CTWD) is significantly longer than recommended. How would an excessively long CTWD primarily affect the welding process and weld quality in FCAW-G?
- AIt would increase the resistance heating of the electrode, reducing current and causing an unstable arc.
- BIt would improve gas shielding, reducing porosity.
- CIt would increase the voltage, resulting in a wider, flatter bead.
- DIt would decrease the wire feed speed, leading to lack of fusion.
Show answer & explanationAnswer & explanation
Correct answer: A. It would increase the resistance heating of the electrode, reducing current and causing an unstable arc.
An excessively long CTWD (stick-out) increases the electrical resistance heating of the electrode wire before it reaches the arc. This preheating effectively reduces the available welding current at the arc, leading to a colder, less stable arc, inconsistent fusion, and often excessive spatter.
Why the other options are wrong
- B. An excessively long CTWD can actually degrade gas shielding effectiveness, increasing the risk of porosity due to atmospheric contamination.
- C. Increasing CTWD (stick-out) generally reduces the effective welding current for a given voltage setting, making the arc colder and less likely to produce a wider, flatter bead.
- D. CTWD doesn't directly decrease wire feed speed; it affects the effective current at the arc for a given wire feed speed.
FCAW Contact Tip-to-Work Distance (CTWD)
The distance from the contact tip to the workpiece in FCAW, significantly impacting current, arc stability, and weld quality.
- Also known as 'stick-out' in some processes.
- Affects resistance heating of the electrode.
- Crucial for maintaining consistent weld parameters.
Memory trick: Long stick-out, low current, lots of trouble.