Taurus MIG-250TD, Operation Manual, Page: 30 / 32

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3. Common Welding Imperfections and Analysis
No. Imperfect Root cause
1 Porosity
1. Impure gas or insufficient gas supply.
2. Absorption of air during welding.
3. Failed preheater.
4. Poor gas shielding owing to strong wind.
5. Torch nozzle blocked by spatter.
6. Too great a distance between nozzle and
workpiece.
7. Polluted welding surface with oil and dust or
moisture caused from insufficient cleaning not
sufficiently removed.
8. Arc length too long and voltage too high.
9. Insufficient silicon and manganese content in
welding wire
.
2
Incomplete
penetration
1. Welding parameters unsuitable for the current job.
2. Welding wire out of position and not aligned with
the centre of the welding bead.
3. Centre deviation of wire feed roller.
4.
Wire straighteners not properly adjusted.
5.
Loose or worn contact tip.
3
Poor
welding
bead
1. Unsuitable welding parameters
2. The welding wire is out of position, and not
aligned
3. with the middle of the welding bead
4. Center deviation of wire feeding roller
5. Wire straighteners is improperly adjusted
6. Contact tip is loosen