Troubleshooting - Lack Of Penetration - Miller Multimatic 255 Owner's Manual

10-11. Troubleshooting – Lack Of Penetration
Possible Causes
Improper joint preparation.
Improper weld technique.
Insufficient heat input.
Incorrect polarity.
10-12. Troubleshooting – Incomplete Fusion
Possible Causes
Workpiece dirty.
Insufficient heat input.
Improper welding technique.
10-13. Troubleshooting – Burn-Through
Possible Causes
Excessive heat input.
10-14. Troubleshooting – Waviness Of Bead
Possible Causes
Welding wire extends too far out of nozzle.
Unsteady hand.
Lack Of Penetration - shallow fusion between weld metal and base metal.
Material too thick. Joint preparation and design must provide access to bottom of groove while
maintaining proper welding wire extension and arc characteristics.
Maintain normal gun angle of 0 to 15 degrees to achieve maximum penetration.
Keep arc on leading edge of weld puddle.
Be sure welding wire extends not more than 1/2 in (13 mm) beyond nozzle.
Select higher wire feed speed and/or select higher voltage range.
Reduce travel speed.
Check polarity required by welding wire, and change to correct polarity at welding power
source.
Incomplete Fusion - failure of weld metal to fuse completely with base metal or a preceeding
weld bead.
Remove all grease, oil, moisture, rust, paint, undercoating, and dirt from work surface before
welding.
Select higher voltage range and/or adjust wire feed speed.
Place stringer bead in proper location(s) at joint during welding.
Adjust work angle or widen groove to access bottom during welding.
Momentarily hold arc on groove side walls when using weaving technique.
Keep arc on leading edge of weld puddle.
Use correct gun angle of 0 to 15 degrees.
Burn-Through - weld metal melting completely through base metal resulting in holes where no
metal remains.
Select lower voltage range and reduce wire feed speed.
Increase and/or maintain steady travel speed.
Waviness Of Bead - weld metal that is not parallel and does not cover joint formed by base
metal.
Be sure welding wire extends not more than 1/2 in. (13 mm) beyond nozzle.
Support hand on solid surface or use two hands.
Corrective Actions
Corrective Actions
Corrective Actions
Corrective Actions
OM-278174 Page 69