1. Shielded Metal Arc Welding (SMAW)
Heat for welding generated by electric arc established between flux-covered consumable metal rod (electrode) and work
Called stick electrode welding
Combustion and decomposition of electrode creases gaseous shield (Gases given off)
Protects electrode tip, weld puddle, arc, and highly heated work from atmospheric contamination
Additional shielding provided by covering of molten slag (flux)
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2. SMAW
American Welding Society
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3. SMAW Advantages Equipment less complex, more portable and less costly
Can be done indoors or outdoors, in any location and any position
Electrodes available to match properties and strength of most base metals
Not used for welding softer metals

4. SMAW Operating Principles
Sets up electric circuit
Includes welding machine, work, electric cables, electrode holder and electrodes, and a work clamp
Heat of electric arc brings work to be welded and consumable electrode to molten state
Heat intense: as high at 9,000ºF at center
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5. SMAW Operating Principle
American Welding Society
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6. Steps to Setting Up Equipment

7. Safety Before We Go Everybody MUST wear GLASSES AND WELDING SHIELD
Stand back 6ish Feet
Make sure you have your Shields DOWN and eyes are protected!
I will warn you when to lower them

8. Application Activity Let’s review the SMW process … 1 = __________
1 = __________
2 = __________
3 = __________
4 = __________
5 = __________
6 = __________

9. SMAW Process 1 2 3 4 5 6 1 4 6 3 2 5 Travel direction Electrode Arc
Weld Puddle 3
Shielding Gas 4
Solidified Weld Metal 5
Slag 6
Electrode 1
Travel direction
Shielding Gas 4
Slag 6 3
Weld Puddle 2
Arc 5
Solidified Weld Metal

10. Parts of a Weld
Arc – Flow of electrons through the electrode ?to the work. Creates heat for welding
Molten Pool (puddle) – Melted metal pool formed from arc heat and the electrode and work
Shielding Gas– Cloud of various gasses used to protect and shield arc and molten pool
Slag – By product of welding process. Infused metals from electrode flux and work. Is on top of ?weld

11. Welding Power Sources
Each type of power source has fundamental electrical differences that best suit particular processes
Welding machine
Must meet changing arc load and environmental conditions instantly
Must deliver exact amount of electric current precisely at right time to welding arc
Available in wide variety of types and sizes

12. Four Types of Power Source
1) Engine-driven generators
Powered by gas or diesel combustion engine
Can be found with a.c. or d.c. electric motor
No longer being manufactured and rarely found
2) Inverters
Increases frequency of incoming primary power
Constant current, constant voltage, or both
Produce a.c. or d.c. welding current

13. Four Types of Power Source
3) A.C. transformers
Used to step down a.c. line power voltage to a.c. welding voltage
4) Transformer-rectifiers
Use basic electrical transformer to step down a.c. line power voltage to a.c. welding voltage
Welding voltage then passed through rectifier to convert a.c. output to d.c. welding current
May be either d.c. or a.c.-d.c. machines

14. Bridge Rectifier
CONVERTS AC to DC

15. Current Controls Amperage Voltage Quantity of current (flow)
Determines amount of heat produced at weld
Voltage
Measure of force of current (push)
Determines ability to strike an arc and maintain its consistency

16. Output Slope Two basic types
1) Constant current – Total welding current(watts) remains the same.
2) Constant voltage – Arc voltage remains constant at the selected setting even if arc length and amperage increase or decrease

17. Affect Arc Length What would effect the temperature of a welding arc?
Voltage
Arc Length
Atmosphere

18. Arc Length Shorter Arc = Lower arc voltage = Lower temp
Longer Arc = more resistance (atmosphere) = higher arc voltage and temp

19. Heat and Amperage Amount of heat produced by Arc = Amperage
Why is the heat important?
Amperage
Heat Produced

20. Lets see it in the shop
Effects of amperage and arc length in shop

21. Electrodes and Amperage
Each electrode (diameter) has recommended minimum and maximum amperage range
Amperage = heat, so they have a heat range

22. Nature of Welding Current
Two types of welding current produced by welding machines
Alternating current
Direct current
Influences selection of electrode
E6010 and E7015 designed for d.c.
E6011, E6013, E7016, E7014, E7018, and E7028 designed for use with a.c.
Perform adequately with d.c.

23. Thickness and Shape of Material to be Welded
General rule
Never use an electrode having diameter larger than thickness of material being welded
Light gauge sheet metal work
1/32-inch or thinner
E6013 electrode designed for this type of work
Least penetration of any electrode in E60XX series

24. Factors Affecting Selection of Electrodes
Type of joint and position of welding
Type of welding current
Properties of the base metal
Thickness of the base metal
Depth of penetration desired

25. Factors Affecting Selection of Electrodes
Weld appearance desired
Whether the work is required to meet code specifications
Tensile strength, ductility, and impact strength required of the weld deposit
Design and fitup of the joint to be welded
Nature of slag removal

26. E7014 Electrode
All-position, alternating current and DCEN or DCEP (fast-fill type)
Covering similar to E6012 and E6013, but thicker due to addition of iron powder
Suitable for welding mild steel in all positions
Weld beads have smooth surface with fine ripples, slag easily removed
Fillet welds flat to slightly convex
Good for production welding on plate of medium thickness

27. E7018 Electrodes All-position, alternating current and DCEP
Low hydrogen, iron powder
Coating contains high percentage of iron powder (25 to 40 percent)
Slag heavy, friable, and easily removed
Deposited metal flat; slightly convex in fillet or groove weld
Welding done in all positions
Electrodes sizes up to 5/32-in

28. E7018 Electrodes (cont.)
Larger diameters used for fillet and groove welds in horizontal and flat positions
Short arc must be held at all times
Strength of deposited weld metal can be improved through addition of certain alloys to coverings
Usually require specific mechanical and chemical properties to meet requirements of base metal

29. Constant Current Welding Machines
Used for shielded metal arc welding and gas tungsten arc welding
Available in both d.c. and a.c. welding current
Current remains fairly constant regardless of changes in arc length
Total Wattage stays the same
Voltage drops as amps increase (dropping arc voltage (DAV) machine)
Enables welder to control welding current in specific range by changing length of arc

30. Open Circuit and Arc Voltage
Open circuit voltage runs between volts (no welding being done, volts high, no amps)
Drops to arc voltage when arc struck
Arc voltages (Voltage generated between electrode and work during welding, voltage lower, amps higher)
Range: 36 volts (long arc) to 18 volts (short arc)
Determined by arc length held by welder and type of electrode used
Arc lengthened, arc voltage increases and current decreases

31. Polarity
Electrode negative and electrode positive used in d.c. welding
DCEN (d.c. electrode negative)
Electrode connected to negative terminal of power source and work connected to positive terminal (current flows from neg to pos) flow from electrode to work = more electrode consumption.
1/3 of heat on electrode. 2/3 on work
High electrical melting rate

32. Polarity DCEP (d.c. electrode positive)
Electrode connected to positive terminal of power source and work connected to negative terminal
2/3 of heat on electrode. 1/3 on work

33. Polarity AC (Alternating Current):
Electrons change direction (alternate) every 1/120th of a second
Electrode and work alternate between anode (+) ?and cathode (-)
Welding heat evenly distributed

34. D.C. Transformer-Rectifier Welding Machines
Have many designs and purposes
Flexibility one reason for wide acceptance
Deliver either DCEN or DCEP
May be used for:
Stick electrode welding
Gas tungsten arc welding
Submerged arc welding
Multi-operator systems
Stud welding
The Lincoln Electric Co.
Miller Electric Mfg. Co.
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35. Transformer-Rectifier Machines
Have two basic parts
1) Transformer for producing and regulating alternating current that enters machine
2) rectifier that converts a.c. to d.c.
Third important part is ventilating fan
Keeps rectifier from overheating
Design improves arc stability and makes it easy to hold short arc which is soft and steady
No major rotating parts so consume little power

36. A.C. Transformer Welding Machines
Most popular a.c. welding machine
Function of transformer
Step down high voltage of input current to high amperage, low voltage current required for welding
Especially suited for heavy work
The Lincoln Electric Co.
Miller Electric Mfg. Co
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37. Advantages of a.c. Power Sources
Reduces tendency to arc blow
Can use larger electrodes
Resulting in faster speeds on heavy materials
Lower cost
Decreased power consumption
High overall electrical efficiency
Noiseless operation
Reduced maintenance

38. D.C. and A.C.-D.C. Inverter Welding Machines
Portable, lightweight, and versatile
May be either constant current, constant voltage or both
Can perform several different processes
Miller electric Mfg. Co.
The Lincoln Electric Co.
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39. Duty Cycle
Percentage of any given 10-minute period that machine can operate at rated current without overheating or breaking down
Rating of 100% means machine can be used at rated amperage on continuous basis
Required by continuous, automatic machine welding
Rating of 60% means machine can be used at its capacity 6 out of every 10 minutes without damage
Satisfactory for heavy SMAW and GTAW

40. Twin Carbon Electrode Holder
Metal shield to protect welder's hand from intense heat.
Two leads are required because the arc is created between the two electrodes.
Larger than the metal electrode holder
The Lincoln Electric Co.
Holder is water cooled
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41. Atomic-Hydrogen Arc Welding
Process in which electric arc surrounded by atmosphere of hydrogen
Gas shields molten metal from oxidation and contamination from the air
Transfers heat from electrode to work
Arc formed between two electrodes
Temperature produced by arc: 7,500ºF
Current supplied by a.c. welding transformer
Hydrogen supplied in cylinders

42. Atomic-Hydrogen Electrode Holder
General Electric Co.
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43. Atomic-Hydrogen Arc Welding
Metal of same analysis as being welded can be deposited
Welds may be heat treated
Unusually smooth, ductile, nonporous and free from impurities
Surface free from scale
May weld hard-to-weld metals
Advantages: increased production, low operating cost, and low maintenance cost