shielded metal arc welding

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Copyright Copyright 2004 Lincoln Global Inc. 2004 Lincoln Global Inc.

Shielded Metal Arc WeldingShielded Metal Arc Welding

SMAWSMAW

EquipmentEquipment

&&

SafetySafety

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What is SMAW?What is SMAW?

SMAWSMAW = Shielded Metal Arc Welding = Shielded Metal Arc Welding

a.a. ““Stick” Welding or “Manual” WeldingStick” Welding or “Manual” Welding

b.b. Metal Rod Covered with Flux that Provides Metal Rod Covered with Flux that Provides Shielding to Protect Shielding to Protect

the Weldthe Weld

c.c. Uses Constant Uses Constant

Current PowerCurrent Power

SourcesSources

d.d. Most Widely Used Most Widely Used Arc Welding Process Arc Welding Process in the World in the World

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Power SupplyPower Supplya.a. Must maintain a constant current (CC) Must maintain a constant current (CC)

with only a slight change in voltagewith only a slight change in voltageb.b. Varying voltage and current will result in Varying voltage and current will result in

a uneven arca uneven arc1)1) Creates splatters & uneven weldsCreates splatters & uneven welds

c.c. Three types of Power SuppliesThree types of Power Supplies1)1) Generator (Portable Welder)Generator (Portable Welder)

- Produces low voltage, high Produces low voltage, high amperage current (D/C)amperage current (D/C)

- Expensive to purchase & operateExpensive to purchase & operate2)2) Transformer (Buzz Box)Transformer (Buzz Box)

– Change high voltage, low amperage Change high voltage, low amperage current (A/C), to low voltage, high current (A/C), to low voltage, high amperage current (A/C)amperage current (A/C)

- Cheapest to purchase & operateCheapest to purchase & operate3)3) RectifierRectifier

- Allows electricity to flow in one Allows electricity to flow in one direction only (D/C)direction only (D/C)

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SMAWSMAW - Power Sources - Power Sources

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Constant CurrentConstant Current

a.a. Welding Circuit Consists of Welding Circuit Consists of Power Source, Electrode and Power Source, Electrode and Work Cables/LeadsWork Cables/Leads

b.b. The Power Source Keeps the The Power Source Keeps the Current as Constant as Current as Constant as Possible even when the Possible even when the Operator Varies the Arc LengthOperator Varies the Arc Length

c.c. Voltage is Proportional to Arc Voltage is Proportional to Arc LengthLength

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The Duty Cycle of a power The Duty Cycle of a power

source is the percentage of a ten source is the percentage of a ten

(10) minute period that it can (10) minute period that it can

operate at the rated output operate at the rated output

current setting. current setting.

Duty CycleDuty Cycle

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Duty CycleDuty Cycle

Duty CycleDuty Cycle AmperesAmperes Time Time AvailableAvailable

30%30% 250 250 3 Min/10 Min3 Min/10 Min 40%40% 225 225 4 Min/10 Min4 Min/10 Min 50%50% 200 200 5 Min/10 Min5 Min/10 Min 60%60% 190 190 6 Min/10 Min6 Min/10 Min 70%70% 180 180 7 Min/10 Min7 Min/10 Min 80%80% 170 170 8 Min/10 Min8 Min/10 Min 90%90% 155 155 9 Min/10 Min9 Min/10 Min 100%100% 140 140 10 Min/10 Min10 Min/10 Min

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Ground Clamp & Electrode Holder Ground Clamp & Electrode Holder

5.5. Ground ClampGround Clampa.a. Completes the full electrical Completes the full electrical

circuitcircuitb.b. Must be fastened securely to the Must be fastened securely to the

base metal or to the bench base metal or to the bench (metal) you are working on(metal) you are working on

c.c. A bad connection will result in A bad connection will result in resistance build-up in the cables resistance build-up in the cables and connectionsand connections

d.d. Resistance generates heat which Resistance generates heat which can damage and/or melt partscan damage and/or melt parts

6.6. Electrode HolderElectrode Holdera.a. The stinger receives the The stinger receives the

amperage and directs it through amperage and directs it through the electrode to form the arcthe electrode to form the arc

b.b. Should be well insulated & have Should be well insulated & have a strong spring to hold the a strong spring to hold the electrodes.electrodes.

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CablesCables

a. Allows the ground clamp and stinger to be mobile

b. Should be well insulated and protected from heat

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ElectrodeElectrode

a.a. Consists of a metal core coated with flux which shields the Consists of a metal core coated with flux which shields the weld as it burns.weld as it burns.

b.b. There are several types and sizes for different thicknesses There are several types and sizes for different thicknesses and types of metal.and types of metal.

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SafetySafety

1.1. Protective ClothingProtective Clothing• Must be worn at all times when Must be worn at all times when

welding. The heat created during welding. The heat created during arc welding creates flying molten arc welding creates flying molten sparks and ultraviolet and infrared sparks and ultraviolet and infrared rays that can burn the skin. rays that can burn the skin.

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Protective Clothing (cont)Protective Clothing (cont)a.a. Leather Gloves Leather Gloves

1)1) Gloves protect the hands Gloves protect the hands from burns during welding. from burns during welding.

2)2) Should be made of thick Should be made of thick leather and have long cuffs leather and have long cuffs to protect the wrist area to protect the wrist area from sparks and heat. from sparks and heat.

b.b. Sleeves Sleeves 1)1) A nonflammable material A nonflammable material

must be worn on the arms must be worn on the arms to protect from burns, to protect from burns, sparks, and ultraviolet sparks, and ultraviolet light.light.

Leather CapeLeather CapeSleeves/BibSleeves/Bib

Leather WeldingLeather Welding JacketJacket

Leather WeldingLeather WeldingGlovesGloves

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Protective Clothing (cont)Protective Clothing (cont)c.c. Body Protection Body Protection

1)1) Leather clothing items Leather clothing items are the best protection are the best protection from heat and sparks. from heat and sparks. For light welding For light welding operations, coveralls operations, coveralls work best but a work work best but a work shirt will protect the shirt will protect the body during arc welding. body during arc welding.

2)2) Protective clothing Protective clothing should fit properly and should fit properly and be free of rips or other be free of rips or other openings through which openings through which sparks can enter. sparks can enter.

d.d. Footwear Footwear

1)1) Leather boots should be Leather boots should be worn while weldingworn while welding

Leather WeldingLeather WeldingTrousersTrousers

Leather Welding Leather Welding ApronApron

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Protective Clothing (cont)Protective Clothing (cont)

e.e. Eye Protection Eye Protection

1)1) The brilliant light given off by The brilliant light given off by the electric arc produces the electric arc produces invisible ultraviolet and infrared invisible ultraviolet and infrared rays which can severely burn rays which can severely burn the eyes and skin. NEVER LOOK the eyes and skin. NEVER LOOK AT THE ARC WITH THE NAKED AT THE ARC WITH THE NAKED EYE! EYE!

2)2) Welding Helmet Welding Helmet • Fits on the head using a plastic Fits on the head using a plastic

adjustable headband. adjustable headband. • This leaves both hands free to This leaves both hands free to

weld and position materials. weld and position materials. • Helmets have a clear cover lens Helmets have a clear cover lens

to protect the filter lens and to protect the filter lens and some have a clear lens some have a clear lens underneath so the welder can underneath so the welder can chip slag.chip slag.

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Protective Clothing (cont)Protective Clothing (cont)g.g. Protective Lenses Protective Lenses

• Different types of welding use different amounts of voltage Different types of welding use different amounts of voltage and current which determine the intensity of light and the and current which determine the intensity of light and the amount of ultraviolet and infrared rays produced. Lens shades amount of ultraviolet and infrared rays produced. Lens shades range from #5 (least protection) to #14 (most protection).range from #5 (least protection) to #14 (most protection).

1)1) Shade 5 Shade 5 Light spot weldingLight spot welding

2)2) Shade 6&7 Shade 6&7 Up to 30 ampsUp to 30 amps

3)3) Shade 8 Shade 8 30 - 70 amps30 - 70 amps



6)6) Shade 14 Shade 14 over 400 ampsover 400 amps

h.h. Cover Lenses Cover Lenses • Used to stop flying slag or metal which protects the filter lens Used to stop flying slag or metal which protects the filter lens

1)1) Clear, unbreakable plastic is cheapest and lasts longest. Clear, unbreakable plastic is cheapest and lasts longest.

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Additional Safety EquipmentAdditional Safety Equipment

i.i. Care of Lenses Care of Lenses 1)1) Must be changed if a crack or chip is found Must be changed if a crack or chip is found 2)2) Periodic cleaning with soap and water is helpful Periodic cleaning with soap and water is helpful

2.2. Additional Welding Equipment Additional Welding Equipment a.a. Tongs/Pliers Tongs/Pliers

1)1) The heat of the arc will transmit to the metal being The heat of the arc will transmit to the metal being welded. Use pliers or tongs to grab or move hot metal. welded. Use pliers or tongs to grab or move hot metal.

b.b. Chipping Hammer Chipping Hammer 1)1) Used to remove slag from the weld Used to remove slag from the weld

c.c. Steel Brush Steel Brush 1)1) Used to clean the weld if a second pass is going to be Used to clean the weld if a second pass is going to be

made. made.

shielded metal arc welding

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