Arc Welding

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Metals and Engineering Industry 5.12AB Perform Routine Manual Metal Arc Welding

ContentsTraining Record Introduction Topics Prerequisites Instructions Competency 3 7 7 7 7 7 9 9 9 10 10

assessment

Section 1 - Introduction to Manual Metal Arc Wdding Aim Acti vity MMAWelding video response Arc welding

Section 2 - Operating Principles for Manual Arc Welding 13 Aim 13 Activity 13 Electricity 14 Hazards 14 Protective clothing 17 Maintenance of welding equipment.. 2021 Welding machines 23 Power source 26 Rating of power sources 29 Current range 29 Electrodes 30 Basic symbols 33 Welding symbols 33 \Velding procedures 35 Joint preparation 37 Review questions - Operating principles for manual arc welding38 Review questions - Weld symbols 42 Review questions - Electrode identification - Current settings .. 44 Section 3 - Manual Metal Arc Welding - Basic Welds Aim Acti vity Manual metal arc welding - basic welds Material preparation HOViT strike an arc to Laying down a weld bead Weld cleaning Review questions - Material preparation and weld cleaning 45 45 45 .46 46 47 48 49 50

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Metals and Engineering Industry 5.12AB Perform Routine Manual Metal Arc Welding

Practical exercise 1 - Beads on plate - flat Procedure sheet 1 - Beads on plate - flat Practical exercise 2 - Pad welds - flat.. Procedure sheet 2 - Pad weld - flat Section 4 - Fillet Weld Joint Terms and Faults Aim Activity Fillet weld joint terminology and faults Fillet weld terminology Weld Defects Workshop tests Review questions - Fillet weld joint terminology and faults Practical exercise 3 - Fillet weld, single run - horizontaL Procedure sheet 3 - Fillet weld, single run - horizontal Practical exercise 4 - Fillet weld, 3 run 2 layer - horizontal.. Procedure sheet 4 - Fillet weld, 3 run 2 layer - horizontal. Practical exercise 5 - Outside corner fillet - horizontal Prooedure sheet 5 - Outside corner fillet - horizontaL Practical exercise 6 - Fillet weld - horizontal Prooedure sheet 6 - Fillet weld - horizontal Seotion 5 - Butt Weld Terminology and Faults Aim Activity Butt weld terminology and faults Weld preparation Preparation types Weld defects The principle of expansion and contraction in a metal Angular distortion Review questions - Butt weld terminology and faults Practical exercise 7 - Butt weld, flat sheet steel Procedure sheet 7 - Butt weld, flat sheet steel

52 54 55 57 59 59 59 60 60 62 67 69 78 80 81 83 84 86 87 89 90 90 90 91 91 93 96 101 101 102 108 110

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Metals and Engineering S.12AB Perform

Industry

Routine Manual Metal Arc Welding

IntroductionThis training guide is designed to support training for the Metal and Engineering Training Package.

Topics Operating principles for manual arc welding Manual metal arc welding - basic welds Fillet weld joint terms and faults Butt weld terminology and faults

PrerequisitesNil

Instructions1. Study the information for each topic and complete review questions Complete the practical exercises.

2.note

The pr~ctical exercises are suggested only and may be replaced by any other suitable training activity. 3. The Training Record must be signed by your trainer on completion of each activity. Complete the theory test. (The test results may be recorded as part evidence of competency.)

4.

Competency assessmentTo achieve competency other approved activities must be entered in the Assessment and Evidence Record section.

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Metals and Engineering S.12AB Perform

Industry

Routine Manual Metal Arc Weldiug

Section 1 - Introduction to Manual Metal Arc WeldingAimTo understand the operating principles, equipment, consumables and safety requirements for general purpose welding using the manual metal arc welding process.

Activity1. 2. View video No. 47 Arc Welding. Complete the video response questions immediately after watching the video. during or

3.

Ask your supervisor or teacher if the information is not clear to you. Ask your trainer to check and sign your Training Record. On completion of this section you must attempt the test on this topic and reach the required level of competence before proceeding to the next section.

4. S.

Safety Wear safety glasses at all times while in welding workshops. Follow safe working practices to avoid electric shock. Weld in well ventilated areas. Wear protective clothing.

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Metals and Engineering Industry 5.12AB Perform Routine Manual Metal Arc Welding

Section 2 - Operating Principles for Manual Arc WeldingAimTo practice manual metal arc welding exercises in order for you to develop the manipulative skills for striking an arc and depositing weld metal on low carbon steel plate.

Activity1. 2. 3. Read and study the resource material following. Complete the review questions. Ask for assistance if the information or instructions are not clear to you. 4. Ask a teacher or your supervisor to check and sign your Training Record.

Safety Follow OHS workshop procedures. Protect your eyes from the welding arc and wear the proper eye protection. Wear suitable protective clothing including dry leather gloves.

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Metals and Engineering Industry S.12AB Perform Routine Manual Metal Arc Welding

The welding process uses electricity and generates heat and fumes. Safety precautions including wearing protective clothing are important. Maintenance of equipment and supplies and a thorough understanding of safety aspects of welding will minimise the risk of accident and injury.

ElectricityElectricity is the flow of electrons through a conductor at a certain pressure and speed. It's like water running through a hose. Some of the terms associated with electricity are explained here. Conductor In welding an electrical conductor is a metal through which electricity will easily flow. Copper is the most used conductor. Voltage This is the unit of electrical pressure. The voltage at the terminals of an AC welding machine is never more than 80 volts for safety reasons. This electrical pressure (or force) is responsible for the current flow in a welding circuit. Amperage This is the measurement of the electron flow,or current, through an electrical conductor. Amperage is measured in amps. An amp is a unit quantity of electricity passing through a given point per second. This is similar to the rate water flows through a pipeline. Electric arc welding process This is also called manual metal arc welding or MMA In MMA a high output amperage (low voltage) is passed W. W through a consumable flux coated electrode and the work piece. This sets up an electrical resistance between the tip of the electrode and the work which causes the electrode to melt off and form a weld bead.

HazardsWorking with electrical equipment can be hazardous. Youmust take proper precautions and follow the set safety procedures. Hazards in the welding workshop include electric shock, fumes, heat, glare and harmful rays.

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Metals and Engineering Industry 5.12AB Perform Routine Manual Metal Arc Welding

Electric shocks - low voltage Electric shocks are possible on the secondary welding circuit. They may be caused by: working on wet floors - a shock may be felt when putting an electrode in the holder. Always stand on insulated mats or wooden boards to reduce the risk and wear dry leather gloves working in a very humid climate or rainy weather - a shock may be felt when changing electrodes. gloves dry. Electrical shocks high voltage High voltage shocks shouldn't happen if precautions are taken such as Keep electrodes and (low voltage) side of the

ensuring welding machines are maintained by licensed electrical tradesmen and that you never interfere with the inside parts of the welding machines. Symptoms of electrical shock Often electric shock stuns but doesn't kill. However when electricity passes through the body it causes muscles to contract from beating or cause breathing to stop. Electricity can also cause serious burns. Fumes Fumes can result from: the production combustion of oxides and nitrous gases from incomplete and can stop the heart

or oxidation of nitrogen from the atmosphere cadmium

the surface coatings on steel such as galvanising, parts/degreasing elements solvents

or chrome plating and paints and solvents such as red oxide

within the parent metal

electrode flux coatings.

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Metals and Engineering S.12AB Perform Routine

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Manual Metal Arc Welding

Safety

Welding should be carried out in well ventilated areas. When welding high fuming materials such asga1vanised steel, use extraction systems to carry away the fumes. If an extraction system is not available, an approved respirator should be used to filter out the fumes. Respirators should only be used as a secondary protection.Dangerous fumes

Gases, dusts and vapours are given off during welding. They can cause: gassing or asphyxiation because the oxygen has been used up in the work area (common in confined spaces) build up of poisonous metals in the body, such as lead, cadmium, zinc, beryllium or mercury respiratory disorders. Heat Heat is a form of energy. When a substance is heated the molecules vibrate or move more rapidly. Heat may be generated by various means. In manual metal arc welding it is generated by the passage of an electric current across an arc;: ap. g The electric arc (about 6000C) generates the heat to melt and fuse the metal surfaces. Heat is transferred in two ways, by conduction and by radiation. Conduction Solid bodies must be in physical contact for heat to travel through them. Some materials conduct heat more rapidly than others. Metals are generally good conductors but, because of their different properties, so