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

AWS
Class
EXX 10
EXX 11
EXX22
EXX 24
EXX 27
Electrode Characteristics
Current
Covering Requirements Position
Cellulose
Sodium
Cellulose
Potassium
Rutile
Sodium
Rutile
50% Iron
Powder
Mineral
50% Iron
Powder
DCEP
AC, DCEP
DCEN, AC
All
All
Flat Decking
Flat, Horiz. Fillet
AC, DCEP, DCEN Flat, Horiz. Fillet
AC,DCEP, DCEN Flat, Horiz. Fillet
Characteristics
Deep Penetration,
With Ripples
Deep Penetration,
With Ripples
Deep Penetration,
With Ripples
High Deposition
Shallow Penetration
High Deposition
Shallow Penetration

Electrode Characteristics continued
AWS
Class
EXX 12
EXX 13
Current
Covering Requirements Position
DCEN, AC All Rutile
Sodium
Rutile
Sodium
AC, DCEP, DCEN All
EXX 14 Rutile
30% Iron
Powder
EXX 18 Low-Hydrogen
30% Iron
Powder
EXX 28 Low-Hydrogen
50% Iron
Powder
AC, DCEN
DCEP, AC
AC, DCEP
All
All
Flat, Horiz. Fillet
Characteristics
Mild to Medium Penetration
Mild Penetration
Medium Penetration
Medium Penetration
High Deposition

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

Fillet
Groove
Kinds of Welds
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