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Manafacture: Hobart Welding Products File size: 1.29 mb File name: o925e_hob.pdf Language of manual:

Remove spatter from gun nozzle. Check gas hoses for leaks. Place nozzle 1/4 to 1/2 in (6-13 mm) from workpiece. Hold gun near bead at end of weld until molten metal solidifies. Wrong gas. Use welding grade shielding gas; change to different gas. Dirty welding wire. Use clean, dry welding wire. Eliminate pick up of oil or lubricant on welding wire from feeder or liner. Workpiece dirty. Remove all grease, oil, moisture, rust, paint, coatings, and dirt from work surface before welding. Use a more highly deoxidizing welding wire (contact supplier). Welding wire extends too far out of nozzle. Be sure welding wire extends not more than 1/2 in (13 mm) beyond nozzle. 9-10. Troubleshooting . Excessive Penetration Good Penetration Excessive Penetration . weld metal melting through base metal and hanging underneath weld. Excessive Penetration S-0639 Possible Causes Corrective Actions Excessive heat input. Select lower voltage range and reduce wire feed speed. Increase travel speed. OM-925 Page 37 9-11. Troubleshooting . Lack Of Penetration Lack of Penetration Lack Of Penetration . shallow fusion between weld metal and base metal. Good Penetration S-0638 Possible Causes Corrective Actions Improper joint preparation. Material too thick. Joint preparation and design must provide access to bottom of groove while maintaining proper welding wire extension and arc characteristics. Improper weld technique. 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. Insufficient heat input. Select higher wire feed speed and/or select higher voltage range. Reduce travel speed. Incorrect polarity. Check polarity required by welding wire, and change to correct polarity at welding power source. 9-12. Troubleshooting . Incomplete Fusion Incomplete Fusion . failure of weld metal to fuse completely with base metal or a preceeding weld bead. S-0637 Possible Causes Corrective Actions Workpiece dirty. Remove all grease, oil, moisture, rust, paint, undercoating, and dirt from work surface before welding. Insufficient heat input. Select higher voltage range and/or adjust wire feed speed. Improper welding technique. 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. 9-13. Troubleshooting . Burn-Through Burn-Through . weld metal melting completely through base metal resulting in holes where no metal remains. S-0640 Possible Causes Corrective Actions Excessive heat input. Select lower voltage range and reduce wire feed speed. Increase and/or maintain steady travel speed. OM-925 Page 38 9-14. Troubleshooting . Waviness Of Bead Waviness Of Bead . weld metal that is not parallel and does not cover joint formed by base metal. S-0641 Possible Causes Corrective Actions Welding wire extends too far out of nozzle. Be sure welding wire extends not more than 1/2 in (13 mm) beyond nozzle. Unsteady hand. Support hand on solid surface or use two hands. 9-15. Troubleshooting . Distortion Distortion . contraction of weld metal during welding that forces base metal to move. Base metal moves in the direction of the weld bead. S-0642 Possible Causes Corrective Actions Excessive heat input. Use restraint (clamp) to hold base metal in position. Make tack welds along joint before starting welding operation. Select lower voltage range and/or reduce wire feed speed. Increase travel speed. Weld in small segments and allow cooling between welds. OM-925 Page 39 9-16. Common MIG Shielding Gases This is a general chart for common gases and where they are used. Many different combinations (mixtures) of shielding gases have been developed over the years. The most commonly used shielding gases are listed in the following table. Gas Application Spray Arc Steel Short Circuiting Steel Short Circuiting Stainless Steel Aluminum Argon X Argon + 25% CO2 X 80% or greater Argon + balance CO2 or Oxygen X X1 100% CO2 X Tri-Mix2 X 1 Limited short circuiting use 2 90% HE + 7-1/2% AR + 2-1/2% CO2 9-17. Troubleshooting Guide For Semiautomatic Welding Equipment Problem Probable Cause Remedy Wire feed motor operates, but wire does not feed. Too little pressure on wire feed rolls. Increase pressure setting on wire feed rolls. Incorrect wire feed rolls. Check size stamped on wire feed rolls, replace to match wire size and type if necessary. Wire spool brake pressure too high. Decrease brake pressure on wire spool. Restriction in the gun and/or assembly. Check and replace cable, gun, and contact tip if damaged. Check size of contact tip and cable liner, replace if necessary. Wire curling up in front of the wire feed rolls (bird nesting). Too much pressure on wire feed rolls. Decrease pressure setting on wire feed rolls. Incorrect...

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