Download Arc Welding- Intro

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Manual arc welding
 Heat for welding generated by electric arc
established between flux-covered consumable
metal rod (electrode) and work
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Called stick electrode welding
Combustion and decomposition of electrode
creases gaseous shield
 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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American Welding Society
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Shielded metal arc welding one of most used
of various electric arc welding processes
9%
2%
13%
42%
SMAW
GMAW/FCAW
GTAW
SAW
Others
34%
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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
 Not as efficient in deposition
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Sets up electric circuit
 Includes welding machine, work, electric cables,
electrode holder and electrodes, and a work
clamp
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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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Electric arc started by striking work with
electrode
Heat of arc melts electrode and surface of
base metal
Tiny globules of molten metal form on tip of
electrode and transferred by arc into molten
pool on work surface
After weld started, arc moved along work
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American Welding Society
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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
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Available in wide variety of types and sizes
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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
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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
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A.C. transformers
 Used to step down a.c. line power voltage to a.c.
welding voltage
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Inverters
 Increases frequency of incoming primary power
 Constant current, constant voltage, or both
 Produce a.c. or d.c. welding current
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Voltage generated by welding machine when
no welding being done
 Machine running idle
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Arc voltage
 Voltage generated between electrode and work
during welding
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Load voltage
 Voltage at output terminals of welding machine
when arc is going
 Combination of arc voltage plus voltage drop in
welding circuit
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1. Sturdy steel lifting eye
2. Large voltmeter
3.Calibrated dial for easy,
fine adjustment of heat
and relation between
voltage and current
4. Outer wheel and dial
for selecting desired
welding range
5. Stop button
Hobart Brothers Co.
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6.Ground cable
connector
7.Optional steel guard
8.Pressed steel bearing cap
9.Heavy-duty ball
bearings
10.Arc welded copper
squirrel cage rotor
11. Motor stator
12. Heavy steel fan
Hobart Brothers Co.
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13.Steel frame
14.Fourpole "Multi-Range"
generator
15. Heavy-duty metallic
graphite brushes
16. Large commutator
17. Heavy-duty ball
bearings
18.Pressed steel bearing cap
19. Arc welded steel frame
Hobart Brothers Co.
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20.Removable steel covers
21.Heavy-duty single unit
steel shaft
22.Welding cable connector
23. Polarity switch
24. Large ammeter
25.Steel turret top with
removable cover
Hobart Brothers Co.
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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
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DCEP (d.c. electrode positive)
 Electrode connected to positive terminal of power
source and work connected to negative terminal
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Switch changes to either electrode positive or
electrode negative
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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
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Lenco dba NLC. Inc.
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Generates heat for several major welding
processes
 Gas tungsten arc welding (GTAW)
 Gas metal arc welding (GMAW)
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Arc cutting utilizes much of same equipment
as arc welding
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Welding heat comes from arc formed
between base metal and carbon electrode or
arc formed between two carbon electrodes
 With or without addition of filler rod
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Carbon electrodes available: 1/4, 5/16, 3/8
inch
Alternating current: 30-125 amperes
Metal electrode holders not suitable
 Carbon electrode hotter than metal electrode
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Two leads are
required because
the arc is created
between the two
electrodes.
Larger than the
metal electrode
holder
Metal shield to protect welder's
hand from intense heat.
The Lincoln Electric Co.
Holder is water cooled
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Now that you have completed your notes:
 Watch the Short video that should appear under
this podcast.
 Then using this website which is off to the side of
links as well complete the vocabulary sheet in
your packet, but take the time to look at some of
the links because there is some cool video, picture
and graphics to go with it