1. Arc Welding
Metals and Welding

2. Precautions and Safe Practices
Relatively safe compared to other forms of welding
4 areas of concern during arc welding
Shock - Fire
Burns - Fumes
Light
Heat

3. Prevention of Shock Use a wooden grating on concrete floors
Rubber soled shoes are best
Danger of shock is increased with higher temperature and humidity - perspiration
Disconnect power before repairing
Qualified electrician should complete maintenance and repairs
Make sure the machine is grounded
Ground clamp – paint, rust, grease will prevent solid ground

4. Prevention of Shock
Use special welding cables with high quality insulation
Repair solid – don’t use tape
Keep in good condition – free of grease, oil, out of water, ditches, etc.
Electrode holders and cables should be fully insulated
Turn main switch to welder off when leaving the work area
Follow usual precautions in handling electric power

5. Prevention of Light Burns
Eyes
Helmet or hand shield with a minimum shade of no. 10 lens is required (see table on )
Wear safety glasses also
Completely screen equipment for arc glare
Locate jobs in special rooms or booths
Avoid accidental contact on the part of others
Skin
Completely cover body
UV Light will cause “sunburn” type burn

6. Prevention of Heat Burns
Clothing
Completely cover body
Sparks and heat
Cotton clothing is preferred with leather shoes and gloves
Mark hot metal to prevent others from coming in contact with welded pieces
Pick up hot metal with pliers or tongues, not gloves or hands
Don’t hand hot metal to instructor or TA’s

7. Prevention of Fire Clothing Do not weld near flammable materials
Stand while Arc welding
Don’t roll cuffs
Keep free of oil, grease, etc.
Sweatshirts turned inside out
Do not weld near flammable materials
Proper fire extinguishing equipment should be stationed near welding operations

8. Prevention of Fumes Exposure
Exhaust systems or breathing apparatus should be provided when welding inside
Fumes from electrode flux – non-toxic
Fumes from paint – lead content - toxic
Fumes from metal coating
Zinc (galvanized), Aluminum - toxic
Carbon monoxide
Carbon dioxide
Dust

9. General Safety Good housekeeping Keep area clean
Electrode stubs
Slag on concrete floor
Cables hung up
Tools put away
Good workmanship in making sound welds is essential to that others may not be injured due to failure of welded parts

10. Stick Electrode Welding
Operation of a miniature electric furnace between the grounded base metal and the electrode
Arc temperature is about 11,000º F
Molten metal must be protected from the air by a gaseous shield and/or slag shield
Machine settings and operator’s manipulations determine size and shape of bead

11. Successful Arc Welding depends upon:
Correct metal identification
Metal properties vary
Correct electrode selection
Depends on metal type, thickness and position of weld
Correct amperage
Depends upon electrode type, size, position, and metal thickness
Influence “burn off rate” and affect arc length and speed of travel

12. Successful Arc Welding depends upon:
Proper Arc length
Influences the amount of heat during the weld
Correct speed of travel
Determines the width of bead and indirectly the strength of the weld
Angle of electrode
Determines the bead shape and controls slag and gas inclusions

13. AC/DC
Alternating Current – electrons change direction every 1/120 of a second (60 cycles per second)
Rapid reversal causes the welding heat to be evenly distributed on both the work and the electrode
Direct Current – flow of electrons in one direction
Electrode Negative (DC Straight) – electrode is negative and the work is positive (high electrode melting rate)
Electrode Positive (DC Reverse) – electrode positive and work is negative (produces the best welding arc characteristics)

14. Electrode Selection
Early arc welding done with bare, low carbon steel wire electrodes on DC welders
Early 1930’s – flux coated electrodes
Exhaustive research into chemical and physical properties and chemical combinations
American Welding Society (AWS) has classified electrodes to allow for wide choices for many applications

15. Classification of Electrodes
Classified according to filler metal specifications by AWS and ASTM (American Society for Testing Materials)
Lincoln, AIRCO, Hobart, etc. will all be the same
Based upon four factors:
Minimum tensile strength of the as-welded deposited weld metal
Type of covering
Welding position
Type of welding current (AC, DC+, DC-)

16. Classification of Steel Electrodes
Electrode designated by “E” followed by a 4- or 5- digit number
First two or three digits - minimum tensile strength as-welded deposited weld metal expressed in thousands of pounds per square inch (1000psi)
E-60xx - 60,000psi TS
E-120xx - 120,000 psi TS

17. Classification of Steel Electrodes
Third or fourth digit refers to the welding position.
E-xx1x - all positions
E-xx2x - flat and horizontal fillet positions
E-xx3x - flat position only

18. Classification cont.
The fourth or fifth and last digit indicates the type of welding current and the type of flux covering
E-xx10 - DC reverse polarity (electrode positive) only (cellulose sodium).
E-xx11 - AC or DC reverse polarity (cellulose potassium ) Fast freeze, cutting
E-xx13 - AC or DC straight polarity (titania potassium) Pg. 161

19. Factors of Electrode Selection
Type of metal to be welded
Thickness of metal
Position of weld
Type of power (DC or AC)
Cleanliness of metal
Weld bead appearance desired

20. Electrode storage Store electrodes in protected place
Avoid cracking or chipping flux by bending or striking
Store in dry place
Aluminum and low hydrogen (E7018) should be stored in a closed container
Old refrigerator works well
Low hydrogen electrodes may be re-dried at 300º F for non-x-ray welds

21. Function of Flux
Improves the performance in handling, storage and operation of the electrode
Floats out impurities
Directs arc stream (stabilizer)
Insulator
Prevents oxidation (slag or gas)
Holds in heat
Iron-powder improves striking ability and increases metal deposition rate (E7024)

22. Selecting the Electrode for the Job
Fast-Freeze-electrodes - deposits a weld that solidifies or freezes rapidly - E6010, E6011.
Fast-Fill - deposits metal rapidly - E7018, E6024, E6027.
Fill-Freeze - characteristics between fast- freeze and fast-fill - E6012, E6013, E6014.

23. Amperage Setting Influences the rate of metal deposition
Influences the speed of welding
Bead should be 2x the diameter of the electrode wire
Type of electrode influences amp. setting
Unusual to select the proper setting on the first try
For ¼” steel, start at 90 amps and adjust from there
Actual amperage is greatly influenced by arc length

24. Striking the Arc “Peck Method Scratch Method DC welders
Contact the plate with downward motion
Scratch Method
AC or DC welders
Contact by sweeping motion

25. Angle of Electrode Arc has a definite directional force Flat welding
Perpendicular from side to side
Tilted in direction of travel about 15º

26. Angle of Electrode by Position
Tee and Lap
45º side; 15-20º lead
6011, 6013, 7024
Horizontal
5-10º side; 15-20º lead
6013, 6011
Overhead
90º side; 10-15º lead
6011
Vertical up
90º side; 0-5º slant
6011
Vertical down
90º side; 10-15º lead
6013

27. Proper Arc Length
Arc welding involves unavoidable changes of arc length
Must be controlled as much as possible
Arc length influences:
Actual amperage (heat)
Appearance of a bead
Arc length should be equal to the diameter of the wire in the electrode (1/8”)
Tighter arc will give even penetration, metal deposition, a strong bead, and less spatter

28. Proper Arc Length Long arc results in: Short arc results in:
Large globules melting
Wavering arc
Wide spatter and irregular bead
Short arc results in:
Electrode sticks
Poor penetration
Convex bead
Clag inclusions
Irregular bead
Use short length for vertical welds

29. Speed of Travel Movement of electrode forward and downward
Travel speed influences:
Bead width
Penetration
General shape of the bead
Use a uniform speed
Both hands on the electrode holder
Operator comfort
Bead should be about twice the diameter of the electrode wire

30. Read the Bead

31. Controlling distortion (Volume changes of expansion followed by contraction during cooling)
Do not overweld.
Avoid continuous welds.
Consider chain intermittent
Or staggered intermittent
Use fewer beads (passes).

32. Controlling distortion cont.
Use 600 included angle on edge prepared joints.
Weld near the neutral axis.
Use back-step welding.
Use wedging.