Troubleshooting − Lack Of Penetration; Troubleshooting − Incomplete Fusion; Troubleshooting − Burn-Through - Miller Electric Bobcat 250 Owner's Manual

15-10. Troubleshooting − Lack Of Penetration
Lack of Penetration
Possible Causes
Improper joint preparation.
Improper weld technique.
Insufficient heat input.
15-11. Troubleshooting − Incomplete Fusion
Possible Causes
Workpiece dirty.
Insufficient heat input.
Improper welding technique.
15-12. Troubleshooting − Burn-Through
Possible Causes
Excessive heat input.
Lack Of Penetration − shallow
fusion between weld metal and
base metal.
Good Penetration
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.
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.
Corrective Actions
Corrective Actions
Corrective Actions
S-0638
S-0637
S-0640
OM-4419 Page 67