INTRODUCTION TO ARC WELDING (SMAW) - FaRudZi4477

INTRODUCTION TO ARC WELDING (SMAW) Terms & Definitions Welding - Joining of two or more pieces of metal together by the fusion process NOTE: In arc welding, heat is produced by the electric arc created.

SMAW - Shielded Metal Arc Welding Electrode - Metal rod which conducts a current from the electrode holder to the base metal Base Metal - Metal to be welded Continued Bead Weld - Made by one pass of the electrode Bevel Type of edge preparation containing an angle

Butt Joint - Weld located between the two edges of metal. Crater - Depression at the end of a weld Safety precautions in SMAW welding Never look at the arc with the naked eye. Use a welding hood that is in good condition and has a #12 shade. Wear suitable clothing to protect all parts

of the body. (PPE) personal protective equipment Long sleeved shirt Leather gloves Collar buttoned Continued Cuffs turned down High topped shoes or boots

Do not strike an arc or weld until you are sure those in the vicinity have protective equipment or will look in the other direction. (Note) Yell cover before striking an arc. Continued Do not weld around combustible or flammable materials. Do not pick up hot metal with the hands.

(NOTE) Use a pair of pliers Do not weld in confined places without ventilation Continued Always turn off main switch or disconnect plug when checking over a welder. Do not leave electrode holder on the welding table or in contact with

grounded metal. Do not use worn or frayed cables. Continued Stand on dry footing when welding. Keep area around welder clean. Keep tools and metals in proper location. Types of Arc Welders A.C. (Alternating current) Welder

current alternates direction 120 times per second. D.C. (Direct current) Welder current flows in the same direction. TIG (Tungsten Inert Gas) Welder may use either A.C. or D.C. with a non-consumable tungsten electrode and an inert shielding gas. Continued MIG (Metal Inert Gas) May use A.C.

or D.C. with a base wire filler material that is fed automatically into weld; also has an inert shielding gas. Common SMAW Tools Welder Electrode Holder Ground clamp Shield or helmet Gloves Chipping hammer

Safety goggles or glasses Wire brush Electrodes Types of Electrodes Mild Steel High Carbon Steel Hard Surfacing Alloys special purpose Electrode Characteristics

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 Electrode Characteristics continued 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 Common Sizes of Electrodes 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. AWS Classification 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 Electrode Coating Functions To Provide Deoxidizers & Scavengers

To Produce Shielding Gases To Produce a Slag Covering To Provide Mechanical and Physical Properties To Increase Deposit Rates Effects of Raising & Lowering Current Raising current Produces more heat

Lowering current Produces less heat (Note: On thicker metals more heat is necessary in order to get penetration of the weld.) Methods of Establishing an Arc Scratching Similar to striking a match

Tapping Straight down and up Characteristics of Proper Arc Length End of electrode is the same distance from the base metal as the diameter of electrode. 1/8 electrode = arc length 1/8 Correct arc length makes a steady

hum of the welder. Correct arc length makes a frying sound at the arc Like bacon frying in a pan Parts of the welding process Electrode Wire core Coating (flux) Arc Gaseous shield

Weld Slag Parts Continued Heat lines Base metal Penetration Crater 15 30 degree angle Direction of travel

Principles of the SMAW Process Kinds of Welds Fillet Groove Bead Fillet Weld Groove Welds

Continued Types of Weld Joints Butt Joint Lap Joint Tee Joint Corner Joint Edge Joint Square Butt Joint

Tee Joints A- plain tee B- single beveled C- double beveled D- single J E- double J Lap Joints A- single lap joint, one weld.

B- single lap joint, two welds. C- offset lap joint. Corner Joints Edge Joints Welding Positions Flat 1F & 1G

Horizontal 2F & 2G Vertical 3F & 3G Overhead 4F & 4G Weld Positions

Reason for Poor Welds 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

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