Welding Standards and Training

For a little under 2 years McClain E-Z Pack hired Jim Davis, a recently retired welding instructor, to work with me on a part-time basis to help the welders improve weld quality. During that time, the question came up, what was the difference between a good weld and a bad weld.

It was decided that showing pictures of good and bad welds was the best way to get the message across. Mr. Davis and I made our own examples of acceptable and unacceptable welding practices and posted the following pictures and comments. The last picture is of an actual production weld.

Problem:

Excessive undercut

Potential Problems:

Failure of Weld

Possible Causes: Voltage too high Welding speed too fast Improper manipulation of weld puddle

Remedies: Raise voltage Lower wire speed Spend more time on outside of weave

Notes:Undercut causes stress risers in a section of the weld zone that may have been hardened as a result of the heat of the weld. Painting does not always cover undercut. This causes rust streaks on the product.

Problem:

Acceptable weld

Potential Problems:

None

Possible Causes: Good work

Remedies: Keep up the good work

Notes:Although amount of spatter in the picture is high the weld size and shape is good. Note also the frequency and shape of the ridges.

Problem:

Acceptable tack

Potential Problems:

None

Possible Causes: Good work

Remedies: Keep up the good work

Notes:Note the size and shape of the middle tack.

Problem:

Oversize tack

Potential Problems:

Difficult to weld over Unneeded expense Weld failure

Possible Causes: Workmanship

Remedies: Make tacks smaller

Notes:Although a decent looking tack, larger tacks are difficult to weld over and avoid excessive weld metal or a bead with “humps” in it. Oversized tacks increase the cost of the production in material, labor and overhead cost. Also see excessive weld metal.

Problem:

Excessive weld metal in weld crater

Potential Problems:

Extra time for cleaners to remove Extra cost in welding wire, shielding gas, man-hours, overhead Looks sloppy Possible weld failure

Possible Causes: Allowing too much for weld termination

Remedies: Increase voltage and amps Increase speed Smaller and more concave tacks

Notes:Excessive weld metal raises the price of the product, lowers efficiency, lowers production, and is a sign of poor workmanship. Excessive weld metal also causes stress risers in the weld which could cause weld failure

Problem:

Poor weld profile, too much on lower leg

Potential Problems:

Weld failure, on top leg

Possible Causes: Wrong torch angle Joining parts of different thickness

Remedies: More attention to both legs of weld Hold torch longer on thicker part

Notes:Uneven legs mean that there is insufficient weld on one leg and could cause the weld to fail, because of an uneven distribution of stress in the legs of the weld.

Problem:

Insufficient weld Improper weld speed

Potential Problems:

Weld failure Increase cause weld fatigue

Possible Causes: Weld speed too fast Improper torch angle

Remedies: Slower speed Increase amperage Decrease voltage

Notes:Note also the tight angles in the ridges on the weld. Besides the obvious problems associated with an insufficient weld, the pointed ridges are a sign that the grains in the metal are not properly interlocking. This could result in a centerline crack within the weld.

Problem:

Good weld crater

Potential Problems:

None

Possible Causes: Good workmanship

Remedies: Keep up the good work

Notes:Excellent, torch angle and direction of travel.

Problem:

Porosity

Potential Problems:

Weld failure Could be a sign of bigger problems under the weld metal

Possible Causes: Poor gas flow Excessive heat Drafts Impurities in weld zone (rust, dirt, moisture) Improper torch angle or stickout

Remedies: Adjust torch angle or stickout Increase weld speed Correct shielding gas Check for drafts in the work area (e.g., open doors, fans, etc…)

Notes:Porosity on the surface of the weld may also be a sign of porosity hidden in the weld metal. Porosity is caused by something disrupting the shielding gas over the weld puddle. It may be caused by excessive as well as insufficient gas flow. Painting does not always cover porosity. This causes rust streaks on the product.

Problem:

Poor weld profile Improper fusion, both legs Improper weld contour Bead face too high

Potential Problems:

Weld failure

Possible Causes: Poor gas flow Excessive heat Poor torch angle

Remedies: Adjust torch angle Increase weld speed Correct shielding gas Decrease wire stick-out

Notes:Give more attention to torch angle, speed of travel, wire stickout, and wire length.

Problem:

Excessive spatter

Potential Problems:

Weld failure Poor workmanship Unneeded cleaning

Possible Causes: Poor gas flow Excessive heat Poor torch angle

Remedies: Adjust torch angle Increase weld speed Correct shielding gas Decrease wire stick-out Decrease voltage or increase amperage

Notes:Spatter just looks bad and cause increased cleaning cost. Spatter may be caused by poor gas flow. See porosity for more possible remedies.

Problem:

Whisker

Potential Problems:

Poor workmanship Unneeded cleaning

Possible Causes: Burning off extra wire Amperage too high

Remedies: Adjust torch angle Increase weld speed Decrease wire stick-out Decrease voltage or increase amperage

Notes:Whiskers just looks bad and cause increased cleaning cost. Whiskers are a sign of poor workmanship and pride.

Problem:

Overlay or Overlap

Potential Problems:

Could cause failure Insufficient penetration

Possible Causes: Poor workmanship Excessive weld Welding too slow Amperage and Voltage too high Joining parts of different thickness

Remedies: Adjust torch angle Increase weld speed Decrease voltage or increase amperage

Notes:Could be a sign that weld isn’t penetrating into base metal on the one side. If this occurs while welding parts of different thickness, hold the torch longer on the thicker part.Painting does not always cover overlap. This causes rust streaks on the product.

Problem:

Super Vertical-Up Weld

Potential Problems:

None

Possible Causes: Good workmanship

Remedies: “Keep up the good work” (says Jim Davis)

Notes:Excellent, torch angle and direction of travel.