Lincoln Electric IM724 Learning to Weld, ARC-WELDING Circuit, SELF-SHIELDED Fcaw Welding ARC

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B-7

 

LEARNING TO WELD

 

B-7

 

 

 

 

 

LEARNING TO WELD

No one can learn to weld simply by reading about it. Skill comes only with practice. The following pages will help the inexperienced operator to understand welding and develop this skill. For more detailed infor- mation, order a copy of New Lessons in Arc Weldinglisted at the end of this manual.

THE ARC-WELDING CIRCUIT

The operators knowledge of arc welding must go beyond the arc itself. The operator must know how to control the arc, and this requires a knowledge of the welding circuit and the equipment that provides the electric current used in the arc. Figure B.7 illustrates the welding circuit for a typical welding machine. The circuit begins where the gun cable is attached to the welding machine. Current flows through the gun cable, gun, and contact tip, to the wire and across the arc. On the work side of the arc, current flows through the base metal to the work cable and back to the welding machine. This circuit must be complete for the current to flow.

This machines welding circuit has a voltage output of 32 volts DC maximum. This voltage is quite low and is only present when the gun triggers depressed.

To weld, the work clamp must be tightly connected to clean base metal. Remove paint, rust, dirt or oil as necessary and connect the work clamp as close as possible to the area you wish to weld. This helps pre- vent current from going through an unwanted path. Avoid allowing the welding circuit to pass through hinges, bearings, electronic components, or similar devices that can be damaged. See Figure B.8. Always disconnect electrical devices before welding upon them.

Electronic Components

WARNING

Fumes and slag generated from Innershield type electrodes recom- mended for use with this welding machine can be toxic.

Avoid contact with eyes and skin.

Do not take internally.

Keep out of reach of children.

Follow all safety precautions found in this operating manual.

The gun and cable assembly is held by the operator who guides the automatically fed wire along the joint, maintaining a contact tip to work distance of about 3/8 to 1/2 inch (10 12 mm) This is called electrical stick- out. This electrical stickout (ESO) must be properly maintained by the operator. The electric arc is made in the gap between the work and the tip end of a small diameter wire. When the power source is properly set, the arc gap is maintained automatically.

Arc welding is a manual skill requiring a steady hand, good physical condition, and good eyesight. The oper- ator controls the welding arc, and, therefore, the quali- ty of the weld made.

THE SELF-SHIELDED FCAW WELDING ARC

Figure B.9 illustrates the action taking place in the self shielded FCAW (Innershield) welding arc. It closely resembles what is actually seen while welding.

HingesBearings

FIGURE B.8

Burning of core materials

Cored Wireinside wire electrode

results in shield of gas.

Protective Slag

Arc Stream

Weld Metal

FIGURE B.9

SP-135T

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Contents SP-135T Safety California Proposition 65 WarningsElectric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcThank You Please Examine Carton and Equipment For Damage ImmediatelyMaster Table of Contents for ALL Sections Installation Technical Specifications SP-135TElectric Shock can kill Safety PrecautionsIdentify and Locate Components Work Clamp Installation Select Suitable LocationOutput Connections StackingGUN Installation Work Cable InstallationConnecting Gun Cable to the SP-135T GAS ConnectionFigure A.5 Requirements For Rated Output Input ConnectionsCode Requirements for Input Connections Design Features OperationGeneral Description Recommended ProcessesLimitations Controls and SettingsWelding Capability Sequence of Operation Wire LoadingWelding Operations Friction Brake Adjustment Wire ThreadingMaking a Weld Cleaning Tip And NozzleProcess Guidelines Overload Protection Changing Machine Over to Feed Other Wire SizesWelding with Gmaw MIG Learning to Weld Learning to WeldARC-WELDING Circuit SELF-SHIELDED Fcaw Welding ARCGmaw MIG Welding ARC Process SelectionCommon Metals Joint Types and PositionsFor Gmaw MIG Process For Fcaw Innershield ProcessFillet Welds Welding In The Vertical PositionPenetration Machine SET UP for the SELF-SHIELDED Fcaw Process Welding Techniques for the SELF- Shielded Fcaw ProcessVertical-down Welding Correct Welding PositionCorrect Electrical Stickout ESO Correct Welding SpeedHelpful Hints PracticeMachine SET UP for the Gmaw MIG Process Welding Techniques for the Gmaw MIG ProcessFor the SP-135T, use the following Troubleshooting Welds To Eliminate a Ropy Convex Bead in order of importanceTo Correct Poor Penetration in order of impor- tance To Eliminate Stubbing* in order of importanceProper Gun Handling Application Chart Accessories Optional AccessoriesK586-1 Deluxe Adjustable Gas Regulator Hose Kit K549-1 .035 0.9 mm Innershield Welding KitInnershield Fcaw Replacement Parts Conversion Routine Maintenance MaintenanceMaintenance Safety Precautions GUN and Cable Maintenance Configuration of Components in Wire Feeding SystemFor Magnum 100L GUN Contact Tip Cable Liner Drive RollChanging Drive Roll Component Replacement ProceduresChanging the Contact TIP Liner trim length Changing LinerGUN Handle Parts Troubleshooting HOW to USE Troubleshooting GuideProblems Possible Areas Symptoms Misadjustments Recommended Course of ActionContact your local Lincoln Authorized Field Service FacilityWelding Problems Diagrams SP-135T Wiring DiagramSP-135T Precaucion