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Title:

Welding

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... GMAW(Gas Metal Arc Welding), wire machine * Advantages Can be used as an automatic welder Can use flux core wire to eliminate gas No slag Continuous weld III ... – PowerPoint PPT presentation

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Title: Welding


1
Welding
LEMMONS
2
  • Arc Welding fusing two or more pieces of metal
    together using heat from an electric arc
  • Advantages of Arc Welding
  • Quick repairs
  • Cheap to operate
  • Arc welder has other uses(cutting, gouging,
    beveling)

3
Types of Welding Machines
  • I. ARC WELDER
  • A. AC Welder
  • SMAW(Shielded Metal Arc Welding)
  • Plugs into any 240 volt outlet
  • Uses AC current
  • Runs up to 225 amps

4
  • Advantages
  • Low cost
  • Easy to maintain
  • Flow
  • 50 heat at electrode
  • 50 heat at work

5
  • B. DC Reverse Current (DC)
  • Deeper penetration
  • Higher possible amps

6
  • 2/3rd heat at work
  • 1/3rd heat at electrode
  • C. DC Straight Current (DC-)
  • Shallow penetration
  • Lower amps
  • Flatter bead
  • 2/3rd heat at electrode
  • 1/3rd heat at work

7
  • AC/DC Welders
  • Combines all three processes into one machine
  • Gasoline Driven Machines

8
  • AC/DC welding machine powered by a gas or diesel
    engine
  • Portable
  • AC generator power to run other tools
  • II. MIG(Metallic Inert Gas)

9
  • Other names
  • hardwire, short arc, GMAW(Gas Metal Arc
    Welding), wire machine
  • Advantages
  • Can be used as an automatic welder
  • Can use flux core wire to eliminate gas
  • No slag
  • Continuous weld

10
  • III. TIG(Tungsten Inert Gas)

11
  • Other Names
  • GTAW(Gas Tungsten Arc Welding) Heliarc
  • Advantages
  • Welds are free of slag
  • Produces the strongest weld
  • No splatter
  • Almost all metals can be welded with the TIG
    process
  • Produce non corrosive welds

12
  • Selecting a Welder
  • Factors to consider
  • Cost
  • Use
  • Select a reliable manufacturer (Lincoln, Miller,
    ESAB)
  • Guarantee or warranty (90 Days, 1 yr, etc.)
  • Service

13
  • Other equipment needed
  • Welding hood
  • Assure proper electrical hookup
  • Pliers
  • Leather gloves
  • Chipping hammer
  • Wire brush
  • Grinder
  • Metal Table

14
Electrodes
  • A. Definition
  • wire, either bare or with flux, used in the
    welding process
  • B. Types of Electrodes
  • 1. Coated electrode metal should match base
    metal. Covered with powder flux.

15
  • 2. Bare- requires excessive heat and is
    voltage sensitive. It is smoke free.
  • 3. Carbon special purpose rod for high
    carbon steel
  • C. Electrode Classification
  • 1. Universal color code and number system

16
Example E7018
  • E - electrode
  • 70 - tensile strength in thousands pounds
  • welding position
  • 1 all position
  • 2 flat and horizontal
  • 3 flat only

17
Example E7018
  • 8 current, penetration, flux, etc.
  • numbers range 0 - 8
  • D. Electrode Size
  • Size is determined by the diameter of the bare
    end of the electrode

18
  • Examples
  • 3/32 electrode
  • 36 rods per pound
  • Run at 30-80 amps
  • 1/8 electrode
  • 17 rods per pound
  • run at 70-120 amps
  • 5/32 electrode
  • 11 rods per pound
  • Run at 120-170 amps

19
  • E. Common Electrodes
  • 6010 mild steel , DC deep penetration
  • 6011 same as 6010, AC/DC
  • 6013 AC/DC, quiet, general purpose
  • 7018 AC/DC, high carbon steel, iron powder flux

20
Selecting an Electrode
  • ID of base metal
  • Available current
  • Metal thickness
  • Joint design
  • Welding position
  • Environmental conditions
  • Storage
  • Building Code

21
8 Essentials to a Proper Weld
  • Proper electrode
  • Metal preparation
  • Proper amperage
  • Proper electrode angle
  • Proper arc length
  • Correct travel speed
  • Proper curing of finished weld
  • Good connected ground

22
I. Preparing Metal for Welding
  • a. Metal should be cleaned
  • b. Dirty metal is harder to weld and requires
    more heat
  • c. Clean metal by brushing, filing, sanding,
    grinding, scraping, sandblasting, chemically

23
  • d. Metal more than ¼ thick metal should be
    beveled at 30 degrees and spaced 1/16 apart
  • e. Bevels one-sided, two-sided, lap, corner

24
II. Amperage
  • a. Too high
  • Flat bead
  • Splatter on bead edge
  • Undercut edges
  • Extremely loud
  • b. Too low
  • high, narrow bead
  • Weak penetration
  • Hard to keep arc going
  • c. Correct
  • Even, steady sound
  • Adequate penetration
  • Uniform in shape

25
III. Electrode Angle
  1. Flat welds electrode angle should be 15 degrees
    to the direction of travel and 90 degrees to each
    side
  2. Vertical welds electrode angle should be on the
    centerline and angled 30 degrees down

26
IV. Arc Length
  • The distance between the electrode and work
  • Arc length should equal the diameter of the bare
    end of the electrode

27
V. Travel Speed
  • How fast or slow the electrode moves across the
    work
  • The bead should remain the same width and height
    at all times
  • Watch the molten puddle to gauge travel speed

28
Methods of Starting an Arc
  1. Scratching - simply drag the electrode across the
    work, lifting it when arc starts
  2. Tapping tap the electrode to the work, picking
    it up quickly while maintaining the arc

29
  • Causes of difficulty starting an arc
  • Flux chipped off end of electrode
  • Flux covering end of electrode
  • Improper amperage(too low)
  • Inadequate ground

30
  • Electrode movement or patterns
  • Slight arch
  • Straight
  • Circular
  • Zig Zag
  • Horseshoe
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