mem05015d weld using manual metal arc welding process · the heat energy required for manual metal...

MEM05 Metal and Engineering

Training Package

Learner guide

Version 1

Training and Education Support

Industry Skills Unit

Meadowbank

Product code: 5583

MEM05015D

Weld using manual metal arc

welding process

SAMPLE

© TAFE NSW (Training & Education Support Industry Skills Unit, Meadowbank) 2012

MEM05015D Weld using manual metal arc welding process

AcknowledgmentsThe TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank would like to acknowledge the support and assistance of the following organisations and people in the production of this learner guide.

• Standards Australia• CIGWELD Australia• Lincoln Electric Co (Australia) Pty Ltd • The Fabricator• Welding Industries of Australia (WIA)

WriterJim Miles (form existing TAFE Resources)

ReviewerEd Harkness (Illawarra Institute)

Project ManagerStephen DaviesEducation Programs ManagerTAFE NSW

EnquiriesEnquiries about this and other publications can be made to:

Training and Education Support Industry Skills Unit, Meadowbank Meadowbank TAFE Level 3, Building J See Street MEADOWBANK NSW 2114

Tel: 02-9942 3200 Fax: 02-9942 3257

© TAFE NSW (Training and Education Support, Industry Skills Unit Meadowbank) 2012

Copyright of this material is reserved to TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank. Reproduction or transmittal in whole or in part, other than for the purposes of private study or research, and subject to the provisions of the Copyright Act, is prohibited without the written authority of TAFE NSW Training and Education Support, Industry Skills Unit Meadowbank.

ISBN 978-1-74236-319-6

SAMPLE



Table of Contents

Introduction ................................................................................... 7

1. General introduction ............................................................................. 7

2. Using this learner guide ......................................................................... 7

3. Prior knowledge and experience ............................................................. 9

4. Unit of competency overview ................................................................. 9

5. Assessment ....................................................................................... 13

Topic 1: Welding safety ................................................................ 19

Review questions ................................................................................... 23

Topic 2: Basic electrical terms and definitions .............................. 25


Topic 3: The manual metal arc welding process ............................. (MMAW) ....................................................................................... 27

Advantages ........................................................................................... 28

Limitations ............................................................................................ 28

Machines............................................................................................... 29

Accessories ........................................................................................... 31

Types of current ..................................................................................... 33

Open circuit voltage (OCV) ...................................................................... 35

Rating of power sources (Duty cycle) ........................................................ 36


Topic 4: Electrodes and electrode classification ............................ 41


Topic 5: Distortion control and weld joints ................................... 51

Weld joints ............................................................................................ 52


Practical jobs and projects ........................................................... 58

Job 1: Fillet weld - vertical....................................................................... 60

Job 2: Fillet weld - section to plate - vertical .............................................. 62

Job 3: Fillet weld - overhead .................................................................... 64

SAMPLE



Job 4: Fillet weld - section to plate - overhead .......................................... 66

Job 5: Butt weld - horizontal .................................................................... 68

Job 6: Butt weld - section to plate - horizontal ........................................... 70

Job 7: Butt weld - vertical ....................................................................... 72

Job 8: Butt weld - section to plate - vertical ............................................... 74

Project 1: Fillet and butt welds - structural section ...................................... 76

Project 2: Fillet and butt welds - plate section ............................................ 78

Resource Evaluation Form ............................................................ 81

SAMPLE


© TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2012 Page 19 of 84

Topic 1: Welding safety

The Work, Health and Safety Act 2011 (WHS Act) and WHS Regulations are enforced throughout all Australian States and Territories. This legislation is aimed at providing consistency, certainty and clarity across Australia making it easy to understand workplace health and safety responsibilities. Consequently this act and its regulations requires both employers and employees to take every reasonable step to work safely and responsibly in the workplace.

There are no “short cuts” to working safety, its everyone’s responsibility to manage and minimise potential risks in the workplace, report faulty equipment as well as unsafe environments. Detailed information relating to the WHS Act and regulations can be found on:

• WorkCover Authority of NSW website www.workcover.nsw.gov.au or on • Safe Work Australia www.safeworkaustralia.gov.au

Welding operators must know about the principles governing the welding operation, equipment used and workplace health and safety precautions required. The following points need to be taken into account when working in a welding environment.

HazardsWorking with electrical equipment can be hazardous. You must take proper precautions and follow set safety procedures.

Electric shocks (low voltage)Electric shocks are possible from the secondary (low voltage) side of the welding circuit. They may be caused by:

• Working in very humid climates or wet/damp conditions - keep your gloves dry at all times

• Workingonwetfloors;ashockmaybefeltwhenputtinganelectrodeintheholder

• Always stand on insulated mats or wooden boards to reduce the risk

• Wear rubber soled shoes for further insulation.

Fumes

• Welding should be carried out in well ventilated areas

• When welding high fuming materials such as galvanized steel, use an exhaust fan to carry away the fumes

• Ifanexhaustfanisnotavailable,anapprovedrespiratorshouldbeusedtofilterthe fumes.

SAMPLE

of 84 © TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2012


Dangerous fumesGases, dusts and vapours are given off during welding. In extreme circumstances they can cause the following:

• Asphyxiationduetotheoxygendepletionintheworkarea(commoninconfinedspaces)

• A build up of poisonous metals in the body, such as lead, cadmium, zinc, beryllium or mercury

• Respiratory ailments from “wheeziness” to serious lung disorders.

Causes of fumes

• The production of oxides and nitrous gases in the arc

• Incomplete combustion or oxidation of nitrogen from the atmosphere

• Elements,compoundsandgasesinthemeltingelectrodefluxcoating

• Metal coatings and surface contaminants vapourising in the arc.

Surface coatings on steel

Sometimes operators will need to weld steel surfaces that have been coated to preserve a corrosion resistance appearance. Typical coatings include:

• Galvanizing

• Cadmium plating

• Chrome plating

• Paints and solvents (such as red oxide coated parts and de-greasing solvents).

Elements within the parent metal

• Elements of steel

• Iron/manganese fumes.

Hot metal, heat and arc radiationMolten droplets have a way of getting onto boots. You can avoid harm by wearing proper protective clothing and footwear.

When welding out of position, for example in the vertical or overhead position, wear spats over your boots and under the legs of your overalls to prevent hot metal sparks or droplets burning your skin.

SAMPLE



Review questions

These questions have been included to help you revise what you have learnt in Topic 1: Welding safety.

1. List three (3) precautions welding operators must take to avoid an electric shock. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________

2. List five (5) items of protective clothing and equipment (PPE) MMAW operators are expected wear. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________

3. Other than electric shock, list two (2) hazards associated with working in a welding environment. ______________________________________________________________ ______________________________________________________________

4. Name the two (2) harmful rays emitted from an electric arc. ______________________________________________________________ ______________________________________________________________

5. Brieflyexplaintheharmfuleffectstheabovearcrayscanhaveontheweldingoperator. ______________________________________________________________ ______________________________________________________________

SAMPLE



Multiple choice questions (Tick the box with the correct answer)

6. Welding over galvanized steel will produce:

o rust resistant welds o stronger welds o poisonous fumes o more ductile welds

7. Weldingfilterlensmustbe:

o shade 13 minimum o approvedandidentifiedtoAustralianStandards o made in Australia o green

8. Ensuring a safe working environment is the responsibility of the:

o employer and employee o welding supervisor o owner of the business o chief engineer

9. The legislation governing the safety of Australians in the workplace is the:

o Work, health and safety act of 2011 o AS1796certificationofweldingoperatorsandsupervisors o NSW OHS act of 2000 o Metal and engineering award.

SAMPLE



Topic 2: Basic electrical terms and definitions

The heat energy required for manual metal arc welding is generated by an electric arcstruckbetweenafluxcoveredelectrodeandtheworkpiece.Theapplicationofelectricity means it is important that welding operators have a basic understanding of electrical terminology an principles associated with MMAW process.

ElectricityElectricity is a form of energy associated with movement of electrons which create a magneticfieldandheatenergy.

VoltageVoltage is the unit of electrical pressure. This electrical pressure (or force) is responsibleforthecurrentflowinaweldingcircuit.Voltageiscommonlyreferredtoas electro motive force (EMF).

CurrentCurrentisthemeasureoftheelectronflowthroughaconductor.Anamperecanbedescribed as a measure (quantity) of electricity passing through a given point per second.Thisissimilartotheratewaterflowsthroughapipeline.

ConductorIn welding, an electrical conductor is a metal through which electricity will easily flow.Copperisthemostusedconductorfollowedbybrassandthenaluminium.

ResistanceElectricalresistanceisameasureofhowstronglyamaterialopposestheflowofelectric current. The unit of resistance is called ohms (Ω).

The electric arcAnarcisgeneratedbyelectronsflowingacrossagapbetweenanelectrodeanda metal workpiece, the electrical energy being changed (converted) into heat and light. The arc is started by momentarily touching or scratching the electrode on the workpiece then withdrawing it about 3 or 4 millimetres to form a gap.

Theflowofelectrons,thatistheweldingcurrent,continuestoflowacrossthesmallgapfirstformedasaspark,orarc.Thesmallgapbecomeselectricallychargedorionizedandcurrentisabletocontinuetoflowacrossthegapintheformofanarc.

A

V

Power source

Voltmeter

Ammeter

Arc

Welding lead Electrode

holder

Electrode

Workpiece Basic power circuit for MMAW

SAMPLE



Review questionsThese questions have been included to help you revise what you have learnt in Topic 2 Basic electrical terms and definitions

1. Definethefollowingelectricalterms:

Voltage: _______________________________________________________

Current: _______________________________________________________

2. Label the parts indicated below associated with a basic MMAW power circuit.

A

V

Power source

3. BrieflyexplainhowanelectricarcisgeneratedwhenMMAW.

______________________________________________________________ ______________________________________________________________ ______________________________________________________________

Multiple choice questions (Tick the box with the correct answer)

4. The unit of resistance in an electrical circuit is called:

o iono high frequency o ohmo electron

5. A material used as a conductor in MMAW electrode and return leads is:

o carbonfibre o carbon steel o copper o reinforced rubber

6. Electricity is a form of energy associated with:

o gravitational forces o arc radiation o expansion of resistors o movement of electrons

SAMPLE

mem05015d weld using manual metal arc welding process · the heat energy required for manual metal...

Documents