INTRODUCTION TO ARC WELDING (SMAW)

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INTRODUCTION TO ARC WELDING(SMAW)
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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

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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

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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

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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.

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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

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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.

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Continued

• Stand on dry footing when welding.
• Keep area around welder clean.
• Keep tools and metals in proper location.

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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.

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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.

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Common SMAW Tools

• Welder
• Electrode Holder
• Ground clamp
• Shield or helmet
• Gloves
• Chipping hammer
• Safety goggles or glasses
• Wire brush
• Electrodes

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Types of Electrodes

• Mild Steel
• High Carbon Steel
• Hard Surfacing
• Alloys special purpose

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Electrode Characteristics
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Electrode Characteristics continued
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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.

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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

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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

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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.)

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Methods of Establishing an Arc

• Scratching
• Similar to striking a match
• Tapping
• Straight down and up

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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

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Parts of the welding process

• Electrode
• Wire core
• Coating (flux)
• Arc
• Gaseous shield
• Weld
• Slag

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Parts Continued

• Heat lines
• Base metal
• Penetration
• Crater
• 15 30 degree angle
• Direction of travel

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Principles of the SMAW Process
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Kinds of Welds

• Fillet
• Groove
• Bead

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Fillet Weld
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Groove Welds
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Continued
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Types of Weld Joints

• Butt Joint
• Lap Joint
• Tee Joint
• Corner Joint
• Edge Joint

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Square Butt Joint
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Tee Joints

• A- plain tee
• B- single beveled
• C- double beveled
• D- single J
• E- double J

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Lap Joints

• A- single lap joint, one weld.
• B- single lap joint, two welds.
• C- offset lap joint.

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Corner Joints
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Edge Joints
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Welding Positions

• Flat
• 1F 1G
• Horizontal
• 2F 2G
• Vertical
• 3F 3G
• Overhead
• 4F 4G

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Weld Positions
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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