INTRODUCTION TO ARC WELDING SMAW Terms Definitions Welding

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

Electrode Characteristics continued

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 E 70 XX-H 4 R • Electrode Tensile in Ksi Welding Position: 1 = All Position, 2 = Flat & Horizontal Type of Current and Coating *Hydrogen: H 4 = Less than 4 ml/100 g weld metal, H 8 = Less than 8 ml/100 g Weld Metal or H 16 = Less than 16 ml/100 g 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 1 F & 1 G Horizontal 2 F & 2 G Vertical 3 F & 3 G Overhead 4 F & 4 G

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