2. Smaw 362i5p

• HISTORY • It is an first invented in arc welding family • MANUAL ARC WELDING • Started with bare electrode welding

• SHIELDED METAL ARC WELDING • Developed With flux coated electrode

• Electric arc started by striking work with electrode • Consumable electrode Process • Heat of arc melts electrode and surface of base metal • Tiny globules of molten metal form on tip of electrode and transferred by arc into molten pool on work surface • After weld started, arc moved along work

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American Welding Society

Shielding (Gas) Flux coating Electrode

4

1

Travel direction Weld Puddle Shielding Gas

6 6

Slag

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Slag Weld Puddle

5

3

2 2

Arc

Arc

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Solidified WeldSolidified Metal Weld Metal

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• Is a consumable - it gets melted during the welding process • Is composed of two parts • Core Rod (Metal Filler)  Carries welding current  Becomes part of the weld

• Flux Coating  Produces a shielding gas  Can provide additional filler  Forms a slag

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• An arc occurs when the electrode comes in with the work-piece and completes the circuit … like turning on a light! • The electric arc is established in the space between the end of the electrode and the work • The arc reaches temperatures of 10,000°F which melts the electrode and base material

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• As the core rod, flux coating, and work pieces heat up and melt, they form a pool of molten material called a weld puddle • The weld puddle is what a welder watches and manipulates while welding

1/8” E6013 at 125 Amps AC 8

• As the molten weld puddle solidifies, it forms a t or connection between two pieces of base material • When done properly on steel, it results in a weld sound with the surrounding base metal

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• Slag is a combination of the flux coating and impurities from the base metal that float to the surface of the weld. • Slag quickly solidifies to form a solid coating • The slag also slows the cooling rate of the weld • The slag can be chipped away and cleaned with a wire brush when hard

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Arc column and weld puddle Shielding (Fumes)

 A shielding gas is formed when the flux coating melts.  This protects the weld puddle from the atmosphere preventing contamination during the molten stateThe shielding gas protects the molten puddle from the atmosphere while stabilizing the arc

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Flux melt in arc column and it deposit as slag over the weld metal to protect the weld metal till the metal cools Slag shall be removed before depositing another layer

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• A.C. – (Alternating current) Welder current alternates direction 120 times per second. • D.C. – (Direct current) Welder current flows in the same direction.

• Two basic types • Constant current • Referred to as variable voltage • Constant voltage • Referred to as constant potential

• Settings on the machine • Polarity : AC, DC+, DC• Amperage Output

• Operator Controlled Variables • • • •

Work Angle Travel Angle Arc Length Travel Speed

A straight AC machine will not have a polarity switch like this AC/DC machine 16

A

B

C

D

E

F

G

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• • • • • • •

Improper power selection Machine adjustment too hot or too cold Electrode size too large or too small Improper movement of electrode Improper angle of holding electrode Improper base metal preparation Arc length too long or too short

•ANSI/AWS - 5.1 : Specification for Covered Carbon Steel •ANSI/AWS - 5.5 : Specification for Low Alloy Steel •ANSI/AWS - 5.4 : Specification for Corrosion Resistant Steel

AWS Website: http://www.aws.org

E70XX-H4R •Electrode Tensile in Ksi Welding Position: 1 = All Position, 2 = Flat & Horizontal

Type of Current and Coating *Hydrogen: H4 = Less than 4ml/100g weld metal, H8 = Less than 8ml/100g Weld Metal or H16 = Less than 16ml/100g weld metal *Meets Requirements of Absorbed Moisture Test *Optional Designators

AWS Class

Covering

Current Requirements

Position

Characteristics

EXX 10

Cellulose Sodium

DCEP

All

Deep Penetration, With Ripples

EXX 11

Cellulose Potassium

AC, DCEP

All Flat Decking

Deep Penetration, With Ripples

EXX22

Rutile Sodium

DCEN, AC

Flat, Horiz. Fillet

Deep Penetration, With Ripples

EXX 24

Rutile 50% Iron Powder Mineral 50% Iron Powder

EXX 27

AC, DCEP, DCEN Flat, Horiz. Fillet

High Deposition Shallow Penetration

AC,DCEP, DCEN Flat, Horiz. Fillet

High Deposition Shallow Penetration

AWS Class

Covering

Current Requirements

Position

Characteristics

EXX 12

Rutile Sodium

DCEN, AC

All

Mild to Medium Penetration

EXX 13

Rutile Sodium

AC, DCEP, DCEN

All

Mild Penetration

EXX 14

Rutile 30% Iron Powder Low-Hydrogen 30% Iron Powder Low-Hydrogen 50% Iron Powder

AC, DCEN

All

Medium Penetration

DCEP, AC

All

Medium Penetration

AC, DCEP

Flat, Horiz. Fillet

High Deposition

EXX 18

EXX 28

• 1/8” • 5/32” • Sizes of electrodes range from 1/16” to 3/8”. • Electrode size is determined by the diameter of the wire core.

Coating Materials -Partial List Arc Stabilizers Titania TiO2 Gas-Forming Materials Wood Pulp Limestone CaCO3 Slag-Forming Materials Alumina Al2O3 TiO2 SiO2 Fe3O4

Slipping Agents to Aid Extrusion Clay Talc Glycerin Binding Agents Sodium Silicate Asbestos Starch Sugar Alloying and Deoxidizing Elements Si, Al, Ti, Mn, Ni, Cr

• ‘Understand and follow all safety precautions listed in ‘Safety in Welding, Cutting, and Allied Processes’ (ANSI Z49.1) and Arc Welding Safety (E205) • Understand and follow all warning labels and material safety data sheet found On welding equipment, consumables, tools • Wear suitable clothing to protect all parts of the body. (PPE) personal protective equipment, fire resistant, shock resistant, light filter • Never look at the arc with the naked eye. The applicable shade shall be used it ranges from 7-14 • Fumes and Gases can be dangerous • Keep your head out of the fumes • Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area • The SMAW process can withstand wind and exhaust near the arc from ventilation equipment • Electric Shock can kill – to receive a shock your body must touch the electrode and work or ground at the same time • Do not touch the electrode or metal parts of the electrode holder with skin or wet clothing • Keep dry insulation between your body and the metal being welded or ground • Arc Rays can injure eyes and skin - Choose correct filter shade (See chart below 25

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Equipment less complex, more portable, Flexible Low initial cost Less sensitive to drafts, dirty parts, poor fit-up Electrodes Readily available for most base metals Less operator training Easy to change between many base materials

Low Deposition Rates Low Productivity Operator Dependent Difficult to weld very thin materials Frequent restarts Lower operating factor Higher operator skill required for SMAW than some other processes • Electrode need baking and storing for long time not advisable • • • • • •

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