Lincoln Electric IM610-A manual Gmaw MIG Welding ARC, Process Selection, For Gmaw MIG Process

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B-9

LEARNING TO WELD

B-9

The “arc stream” is seen in the middle of the picture. This is the electric arc created by the electric current flowing through the space between the end of the wire electrode and the base metal. The temperature of this arc is about 6000°F, which is more than enough to melt metal. The arc is very bright, as well as hot, and cannot be looked at with the naked eye without risking painful injury. The very dark lens, specifically designed for arc welding must be used with the hand or face shield whenever viewing the arc.

The arc melts the base metal and actually digs into it much as water through a nozzle on a garden hose digs into the earth. The molten metal forms a molten pool or crater and tends to flow away from the arc. As it moves away from the arc, it cools and solidifies.

The function of the Innershield cored wire electrode is much more than simply to carry current to the arc. The wire core is composed of fluxes and/or alloying ingre- dients around which a steel sheath has been formed. It is simply a stick electrode turned inside out in a con- tinuous wire form.

The cored wire melts in the arc and tiny droplets of molten metal shoot across the arc into the molten pool. The wire sheath provides additional filler metal for the joint to fill the groove or gap between the two pieces of base metal.

The core materials also melt or burn in the arc and perform several functions. They make the arc stead- ier, provide a shield of smoke-like gas around the arc to keep oxygen and nitrogen in the air away from the molten metal, and provide a flux for the molten pool. The flux picks up impurities and forms the protective slag on top of the weld during cooling.

After running a weld bead, the slag may be removed with a chipping hammer and wire brush. This improves appearance and allows for inspection of the finished weld.

Since machine size and output characteristics limit the size and type of wire electrode which can be used, Lincoln 0.035" and 0.045" (0.9 and 1.2 mm) NR-211- MP Innershield electrode is recommended for Self- Shielded Flux Cored Arc Welding with this machine.

THE GMAW (MIG) WELDING ARC

Figure B.10 illustrates the GMAW (MIG) welding arc. Solid wire does not contain fluxes or ingredients to form its own shielding and no slag forms to protect the molten weld metal. For this reason, a continuous even flow of shielding gas is needed to protect the molten weld metal from atmospheric contaminants such as oxygen and nitrogen. Shielding gas is supplied through the gun and cable assembly, through the gas nozzle and into the welding zone.

 

 

 

 

Gas nozzle

 

 

 

 

Shielding gas

 

Solid wire

 

electrode

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Weld metal

Base metal

 

 

 

 

 

 

 

 

 

 

 

FIGURE B.10

When comparing the GMAW and FCAW processes, you can see that the principal difference between the two lies in the type of shielding used. GMAW uses gas for shielding, thus we have Gas Metal Arc Welding. FCAW uses the melting or burning of the core ingredi- ents for shielding, and is thus termed Self-Shielded Flux Cored Arc Welding.

The recommended wire for Gas Metal Arc Welding (MIG) is Lincolnweld 0.025” (0.6 mm) L-56 electrode. Lincolnweld” L-56 is capable of welding a wide range of mild steels in all positions, however, more skill is required for out-of-position welding with the GMAW process.

PROCESS SELECTION

By gaining knowledge of the differences between the two processes, you will be able to select the best process for the job you have at hand. In selecting a process, you should consider:

For GMAW (MIG) Process

1.Is most of my welding performed on 16 gauge and lighter materials?

SP-175 PLUS

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Contents SP-175 Plus Safety California Proposition 65 WarningsElectric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a LʼArcThank You Please Examine Carton and Equipment For Damage ImmediatelyTable of Contents Installation Installation Safety PrecautionsRead entire installation section before starting Identify and Locate ComponentsSelect Suitable Location Work Clamp InstallationWork Cable Installation StackingConnecting Gun Cable to the SP-175 Plus GUN InstallationGAS Connection Gas Solenoid Inlet Fitting Power Input Cable Input ConnectionsElectrical Input Connection for Rated Output Line Cord ConnectionVolt Input Connection Fumes and Gases can be dangerous Observe all safety information throughout this manualOperation Welding Sparks can cause fire or explosionGeneral Description Controls and SettingsDesign Features Advantages Welding CapabilityWelding Operations Wire LoadingSequence of Operation Friction Brake Adjustments Wire ThreadingShielding Gas Making a WeldCleaning Tip And Nozzle Changing Machine Over to Feed Other Wire SizesProcess Guidelines Output Overload Wire Feed Overload ProtectionOverload Protection Thermal ProtectionARC-WELDING Circuit Learning to WeldLearning to Weld SELF-SHIELDED Fcaw Welding ARCProcess Selection Gmaw MIG Welding ARCFor Gmaw MIG Process For Fcaw Innershield Process Common MetalsJoint Types and Positions Butt WeldsPenetration Welding In The Vertical PositionFillet Welds Vertical-down Welding Machine SET UP for the SELF-SHIELDED Fcaw ProcessWelding Techniques for the Self Shielded Fcaw Process Correct Welding PositionCorrect Electrical Stickout ESO Correct Welding SpeedHelpful Hints PracticeMachine SET UP for the Gmaw MIG Process Welding Techniques for the Gmaw MIG ProcessFigure B.24 To Eliminate a Ropy Convex Bead in order of importance Troubleshooting WeldsTo Correct Poor Penetration in order of impor- tance To Eliminate Stubbing* in order of importanceProper Gun Handling Application Chart K1799-1 Argon-Mixed Gas Adjustable Regulator and Hose Kit AccessoriesOptional Accessories K586-1 Deluxe Adjustable Gas Regulator Hose KitReplacement Parts Innershield Fcaw ConversionItems Requiring no Maintenance MaintenanceMaintenance Safety Precautions Routine and Periodic MAINTE- NanceFor Magnum 100L GUN GUN and Cable MaintenanceConfiguration of Components in Wire Feeding System Contact Tip Cable Liner Drive RollChanging Drive Roll Changing the Contact TIPRoll onto the drive shaft SP-175 Plus Changing Liner Liner trim lengthGUN Handle Parts Figure D.3 SP-125 PlusTroubleshooting HOW to USE Troubleshooting GuideProblems Possible Areas Symptoms Misadjustments Recommended Course of ActionGAS Flow Problems Welding Problems Wiring Diagrams SP-175 Plus Wiring Diagram CodePage Need Welding Training? How To Read Shop DrawingsNew Lessons in Arc Welding $700.00Precaucion Warnung