Transcript Document
SMAW
SMAW
SHIELDED METAL ARC WELDING
AWS Classification
ARC WELDING
STICK WELDING
FACTS ABOUT SMAW
Originated at start of WWI for shipbuilding
SMAW is the least expensive arc welding processes
Is the most widely used welding process in the world
Can be used to weld most common metals and alloys
SMAW COMPONENTS
1- The Electrode
• Consumable…
• 2 Part Composition
Core Rod (Metal Filler)
Carries welding current &
Becomes part of the weld
Flux Coating
Produces a shielding gas &
helps form slag
6
2- The Arc
Can you identify the weld joint
and position being used?
• Turn on the light…An arc
occurs when the electrode
comes in contact with the
work-piece and completes
the circuit
• The electric arc is
established in the space
between the end of the
electrode and the work
causing resistance
• The arc reaches
temperatures of 10,000°F
which melts the electrode
and base material
7
3- Weld Puddle
• As the core rod, flux
coating, and work
pieces heat up and
melt, they form a pool
of molten material
called a weld puddle
• The weld puddle is
what a welder watches
and manipulates while
welding
1/8” E6013 at
125 Amps AC
8
4- Shielding Gas
• A shielding gas is formed when the flux melts.
• This protects the weld puddle from the atmosphere
preventing contamination during the molten state
The shielding gas protects the
molten puddle from the
atmosphere while stabilizing
the arc
Shielding Gas
4
3
2
9
5- Solidified Weld Metal
• As the molten weld puddle solidifies, it forms a
joint or connection between two pieces of base
material
• When done properly on steel, it results in a weld
stronger than the surrounding base metal
• Bead width = 2.5 to 3 times electrode diameter
3/8”
10
6- Slag
•
•
•
•
•
•
Combination of melted flux & base metal impurities
Quickly solidifies to form a shell
Slows the cooling rate of weld
Chip and clean with hammer & brush
If proper technique is used it should come off easy
Never weld over slag!!
ALWAYS SIDE CHIP SLAG, DON’T
HIT IT LIKE A HAMMER
11
Slag You Drag!
• Slag Welding Processes
– ALWAYS PULL THE PUDDLE
– Shielded Metal Arc Welding (SMAW)
– Flux Core Arc Welding (FCAW)
• No-Slag Welding Processes
–
–
–
–
ALWAYS PUSH THE PUDDLE
Gas Metal Arc Welding (GMAW)
Gas Tungsten Arc Welding (GTAW)
Oxy-Fuel Welding
SMAW Process
Electrode
1
Travel direction
4
6
6
Shielding Gas
Slag
Slag
Weld Puddle 3
3 Weld Puddle
5
5
13
Solidified Weld Metal
Solidified Weld Metal
2
2
Arc
Arc
Activity
Let’s review the SMAW process … • 1 = __________
1
• 2 = __________
• 3 = __________
4
• 4 = __________
6
• 5 = __________
3
2
• 6 = __________
5
14
AWS Electrode Classification
Electrode Selection
•
•
•
•
•
•
What type of welder do I have, AC or DC?
What am I welding, steel, cast, stainless, etc?
What is the metal condition, dirty or clean?
Is it a root or cover pass?
How strong does it have to be?
What electrodes do I have to chose from?
Electrode Selection
Amperage Chart
• Amperage is dependent on electrode
diameter, electrode type, and metal thickness
• Reference charts whenever possible.
Amperage Electrode
• Shorthand method will get you in the
ballpark for fast freeze electrodes.
Not 100% accurate for all electrodes!
AWS: 1/8” diameter E6013
1/8”= .125”
125 Amps
Electrode Care
• Electrodes must be kept dry
– Dampness will introduce hydrogen into the
weld causing cracking or brittleness
– Damp electrodes may cause the flux to “blow
away” & cause porosity
– Bake questionable electrodes for several
hours.
– 6010 & 6011 (fast freeze) are exempt
• Our electrodes are stored in a dry oven
Electrodes Care cont.
•
•
•
•
•
Burn electrodes down to numbers!
Place stubs in stub box
Put unused electrodes back in oven
Only grab several electrodes at a time
Electrodes are not cheap
Striking an Arc and Making a Weld
22
Striking an Arc
• To begin the SMAW Process, you must first
strike an arc.
– Scratch start – scratch the electrode on the base
metal like a match
– Tap Start – tap the rod against the base metal
23
Work Angle
• The work angle is the
angle between the
electrode and the work
as depicted on the left
90°
• Work angles can vary
depending on the
position the weld is being
made in
24
Travel Angle
• Also commonly called
Lead Angle
20-30°
• The travel (lead) angle
is the angle between
the electrode and the
plane perpendicular to
the weld axis
25
Arc Length
• After striking the arc, maintain a 1/8”
distance between the electrode and the
workpiece
– Too short: electrode will fuse itself to metal
– Too long: spatter, undercut, and porosity
Arc Length = 1/8”
26
Travel Speed
• Speed at which the electrode moves along the
base material while welding
– Too fast: ropey or convex weld
– Too slow: wide weld, excessive deposit
The travel speed impacts
the shape of the bead.
27
Filling the Crater
• At the end of the weld, the operator breaks the
arc which creates a ‘crater’
• Use a short pause or slight back step at the end
of the weld to fill the crater
• Large craters can cause weld cracking
Back stepping is a short
move in the opposite
direction of weld travel
28
Restarting a Bead
• Remove electrode from stinger
• Scratch electrode until metal can be seen
• Scratch in weld line: spatter
1. Strike Arc Here
2. Move Electrode to
Crown of Crater
3. Resume Travel
29
Troubleshooting Activity
On a piece of scratch paper, describe welds A-G.
Good, bad, arc length, speed, lead angle, etc.
A
30
B
C
D
E
F
G
•
•
•
•
•
•
•
A – Good Weld: Proper Current, Speed and Arc Length
B – Current low: Ropey, convex bead appearance
C – Current too High: Excess spatter & burn-through
D – Arc Length too short: Poor wet-in at toes
E – Arc Length too Long: Spatter, undercut and porosity
F – Travel Speed too slow: Wide weld with excess deposit
G – Travel Speed too high: Ropey and convex bead
Lincoln V350 SMAW Setup
1.
2.
3.
4.
Plug ground cable into the (-) terminal
Plug the whip cable into the (+) terminal
Turn on the welder
Select SMAW (CC-Stick Soft) mode
–
CC-Stick Crisp is for pipe welding
5. Select correct amps
6. Set Hot start to 2-3
–
(This will make starting the arc easier)
7. Set Arc Control to +4-5
–
–
(high arc control = crisp weld but more spatter)
(low arc control = soft weld with little spatter)