Miller Electric MPi 220P Owner's Manual page 70

Lack of Penetration
Good Penetration
Possible Causes
Improper joint preparation.
Improper weld technique.
Insufficient heat input.
Good Penetration
Excessive Penetration
Possible Causes
Excessive heat input.
Possible Causes
Excessive heat input.
Possible Causes
Unsteady hand.
Base metal moves
in the direction of
the weld bead.
Possible Causes
Excessive heat input.
OM-253 918 Page 64
Lack Of Penetration − shallow fusion between weld metal and base metal.
Corrective Actions
Material too thick. Joint preparation and design must provide access to bottom of groove.
Keep arc on leading edge of weld puddle.
Increase amperage. Select larger electrode and increase amperage.
Reduce travel speed.
Excessive Penetration − weld metal melting through base metal and hanging underneath weld.
Corrective Actions
Select lower amperage. Use smaller electrode.
Increase and/or maintain steady travel speed.
Burn-Through − weld metal melting completely through base metal resulting in holes where no
metal remains.
Corrective Actions
Select lower amperage. Use smaller electrode.
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.
Corrective Actions
Use two hands. Practice technique.
Distortion − contraction of weld metal during welding that forces base metal to move.
Corrective Actions
Use restraint (clamp) to hold base metal in position.
Make tack welds along joint before starting welding operation.
Select lower amperage for electrode.
Increase travel speed.
Weld in small segments and allow cooling between welds.