SMAW Stick Welding PPT - Center - Center

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SMAW
(Stick Welding)
Chapter 5
SMAW Principles
2
SMAW Principles
• The American Welding
Society defines SMAW as
Shielded Metal Arc
Welding
• SMAW:
– Is commonly known as
‘Stick’ welding or manual arc
welding
– Is the most widely used arc
welding process in the world
– Can be used to weld most
common metals and alloys
3
SMAW Welding Circuit
• Current flows through the electrode cable, to the
electrode holder, through the electrode, and across the
arc
• On the work side of the arc, the current flows through the
base material to the work clamp and back to the welding
machine
4
5
SMAW Process
Let’s take a little closer look at the SMAW process…
Electrode
1
Travel direction
Shielding Gas
4
6
6
Slag
Slag
Weld Puddle 3
3 Weld Puddle
5
5
2
2
Arc
Arc
Solidified Weld Metal
Solidified Weld Metal
6
Application Activity
Let’s review the SMW process …
1
•
1 = __________
•
2 = __________
•
3 = __________
•
4 = __________
•
5 = __________
•
6 = __________
4
6
3
2
5
7
1- The Electrode
• Is a consumable - it gets
melted during the welding
process
• Is composed of two parts
– Core Rod (Metal Filler)
 Carries welding current
 Becomes part of the weld
– Flux Coating
 Produces a shielding gas
 Can provide additional filler
 Forms a slag
8
2- The Arc
Can you identify the weld joint
and position being used?
• An arc occurs when the
electrode comes in
contact with the workpiece and completes the
circuit … like turning on a
light!
• The electric arc is
established in the space
between the end of the
electrode and the work
• The arc reaches
temperatures of 10,000°F
which melts the electrode
and base material
9
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
10
4- Shielding Gas
Shielding Gas
4
3
2
The shielding gas protects the molten
puddle from the atmosphere while
stabilizing the arc
• A shielding gas is
formed when the
flux coating melts.
• This protects the
weld puddle from
the atmosphere
preventing
contamination
during the molten
state
11
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
12
6- Slag
• Slag is a combination of the flux
coating and impurities from the
base metal that float to the
surface of the weld.
• Slag quickly solidifies to form a
solid coating
• The slag also slows the cooling
rate of the weld
• The slag can be chipped away
and cleaned with a wire brush
when hard
This welder chips the slag off of a
weld during the repair of railroad
tracks
13
Equipment
14
A complete SMAW Station
• A complete shielded metal arc welding station consists
of:
–
–
–
–
–
A Welding Machine
An Electrode Lead
An Electrode Holder
A Workpiece Lead
A Workpiece Ground Clamp
15
Welding Leads
• Welding Leads: large diameter, super flexible leads
(cables) are used to carry current from the welding
machine to the work and back.
– Electrode Lead: The lead from the machine to the electrode
holder.
– Work piece lead or ground lead: The lead from the work to the
machine.
• Leads are well-insulated with rubber and a woven fabric
reinforcing layer.
• Leads are subjected to considerable wear and should
be checked periodically for breaks in the insulation.
16
Welding Leads
• Leads are produced in several sizes.
– The smaller the number, the larger the diameter.
• The lead must be flexible to permit easy installation of
the cable, and to reduce the strain on the arc welder’s
hand when welding.
• To produce this flexibility as many as 800 – 2500 fine
wires are used in each cable.
• The SAME diameter electric cable must be used on
both the electrode and work piece leads.
– The length of the lead has considerable effect on the size to be
used for certain capacity machines.
– Use short leads to minimize current loss due to the lead
resistance.
17
Electrode Holders
• Electrode Holder: the part of the arc welding equipment
held by the operator when welding. Holds the electrode.
– Many different styles and models are available, but they all
have similar characteristics.
18
Weld-Cleaning Equipment
• It is very important that the base metals in weldments
be cleaned prior to welding.
– It is difficult to weld dirty or corroded surfaces.
 Resulting welds will normally be of poor quality.
• Weldments: A unit composed of an assemblage of
pieces welded together.
19
Chipping Hammer
• Chipping hammers are often double-ended.
– One end is shaped like a chisel for general chipping.
– The other end is shaped like a pick, for reaching into corners
and narrow spaces.
20
Headgear
• Arc welding requires the use of special equipment to
protect skin surfaces, such as the hands, face and eyes.
• The Occupational Safety and Health Administration
(OSHA) requires the use of a hard hat with the arc
welding helmet on construction sites.
21
Arc Welding Helmet
• An Arc Welding Helmet is used to
protect the face and eyes.
– It is mounted and supported on the
head
– Made of fiber, plastic or fiberglass
and is formed in a shape that covers
the front half of the head.
– Headbands on the helmets are
adjustable
– There is an tension adjustment that
keeps the helmet up.
 You can adjust the tension so a slight
nod of the head will allow the helmet
to rotate down over your face
22
Welding Helmet Lenses
•
A good grade of colored arc welding filter lens will
remove approximately 99.5% of the infrared rays and
99.75% of the ultraviolet rays from the light emitted by
the arc.
• U.S. Bureau of Standards developed recommended
shades for various arc welding applications.
– Shade number 10, 12 and 14 are the common ones used for
SMAW.
– The higher the shade number, the lower the transmission of
infrared or ultraviolet rays.
– Autodarkening: Helmets have been developed that have a
battery-powered photoelectric cell built in.
 The lens is clear until an arc is struck.
 The circuitry of the photoelectric cell then instantly darkens the
lens.
23
Arc Safety
• Excess ultraviolet rays may cause eye pain for 8 to 18
hours after exposure.
• Infrared and ultraviolet light rays can severely injure the
eyes; every precaution should be taken to shield the
eyes from these rays.
24
25
Shield
• A shield is used in a metal shop
for jobs such as grinding and
cutting.
– Similar design to a welding helmet.
– Headbands on the shield are
adjustable.
– Made of fiber, plastic or fiberglass
and is formed in a shape that
covers the front half of the head.
– Can not be used to weld with.
26
Safety Glasses
• A welder must wear safety glasses at all time under a
welding helmet or shield.
• They enable the operator to set up work, chip welds and
still have eye protection from flying particles.
27
Clothing
• While an arc weld is in progress, the molten flux and the
metal itself sometimes spatter for a considerable
distance around the joint being welded.
• The operator must, therefore, be protected from the
danger of being burned by these hot particles.
• Such clothing as gloves, cap, cape, shoes and aprons.
• All these clothing articles should be made of leather or
approved clothing for welding.
28
Welding Gloves
• Welding gloves are
made of leather and
are wore during
welding.
• Gloves should be
worn to cover the
hands and wrists and
to prevent “sunburn”
– During the welding
process, skin not
covered will be
exposed to UV rays
and sunburned.
29
Welding Cap
• A welding cap can be
worn underneath the
welding helmet.
• Protects top of head from
spatter.
• Helpful when welding
overhead.
30
Welding Cape
• A welding cape is worn to
protect shoulders and
arms from spatter.
31
Welding Boots
• Welding boots should be
made of leather and high
topped.
• NO tennis shoes
32
Welding Pants
• Pants should be jean/coverall
material.
• Pants worn by the welder should
not have cuffs.
• Cuffs may catch burning
particles as they fall.
33
Welding Aprons
• A welding apron can be
worn over a long sleeve
shirt during welding to
protect the front of the
operator.
34
AWS Classification of
SMAW Electrodes
35
SMAW Electrodes
• Electrodes have a solid metal wire core and a thick flux
covering (coating).
• These electrodes are identified by the wire diameter and
by a series of letters and numbers.
• These letters and numbers identify the metal alloy and
the intended use of the electrode.
• The common diameters are 1/16”, 3/32”, 1/8”, 5/32”,
3/16”, 7/32”, 1/4”, 5/16”, and 3/8”.
– Available in lengths from 9” to 18”. Most common is 14”.
• The electrodes are usually purchased in 50 lb.
packages
36
SMAW Electrodes
• SMAW electrodes are produced for welding on many
metals and alloys including:
–
–
–
–
–
–
–
–
Carbon Steels
Low-Alloy Steels
Corrosion-Resistant Steels
Cast Irons
Aluminum and Aluminum alloys
Copper and Copper Alloys
Nickel and Nickel Alloys
Surfacing
• Alloy: Pure metal that has additional metal or nonmetal
elements added while molten. The alloy has mechanical
properties that are improved from the pure metal.
37
SMAW Electrodes
• Flux: The covering on a shielded metal arc welding
electrode
• The flux on the electrode performs many different
functions.
–
–
–
–
–
1. Producing a protective gas around the weld area.
2. Providing fluxing elements and deoxidizers.
3. Creating a solid coating over the weld as it cools.
4. Establishing electrical characteristics.
5. Adding alloying elements.
38
1. Protective Gas
• During the arc process, some of the flux covering
changes to neutral gases or reducing gases such as
carbon monoxide (CO) or hydrogen (H).
– These gases prevent oxygen from coming in contact with the
molten metal.
39
2.Fluxing Elements
• The covering also contains special fluxing ingredients
that work to remove impurities from the molten metal.
– Impurities are floated to the top of the molten weld pool.
40
3. Solid Coating
• Slag: As the electrode flux coating residue cools, it
forms a coating of material over the weld called slag.
– Prevents the air from contacting the hot metal.
– Allows the weld to cool more slowly and helps prevent a hard,
brittle weld.
41
4. Electrical Characteristics
• When welding with AC, the current changes direction
and actually stops 120 times per second.
• To maintain an arc as the current changes directions,
ingredients are added to the covering of the electrode to
create an ionized gas.
– This gas allows good arc stability when welding with AC.
42
5. Alloying Elements
• Alloying elements are added to the weld pool as the
covering is melted.
– These electrodes deposit metal into the weld at a faster rate
than standard electrodes.
• A good flux-covered electrode can produce a weld that
has excellent physical and chemical properties.
43
Electrode Classification
• The American Welding Society has developed a series
of identifying number classifications.
• Uses four or five digits.
44
AWS Classification
of SMAW Electrodes
E70XX
Electrode
Tensile in Ksi
Welding Position:
1 = All Position, 2 = Flat & Horizontal
Type of Current and Coating
45
Tensile Strength
• E: indicates a welding electrode used in
arc welding.
E70XX
46
Tensile Strength
• The first two or three digits represent
the tensile strength
E70XX
– E70XX = 70,000 psi, E100XX = 100,000psi
– Psi: Pounds per square inch
• May also be shown as ksi
– Ksi: Kilopounds per square inch
– 70 ksi = 70,000 psi
47
Welding Position
• The second digit from the right indicates
the recommended position of the joint
that the electrode is designed to weld.
E70XX
– EXX1X: Will weld in all positions
– EXX2X: Are used for welds in the flat or
horizontal welding position only.
48
Type of Current and Coating
• The last two digits need to be looked at
together.
• The two digits give the welder
information on the electrode covering,
current to use and position to use the
electrode.
• *Refer to chart for more information
E70XX
49
50
CHAPTER 6
51
Electricity
• Electricity flows in two ways: Either in an alternating
current (AC) or in a direct current (DC).
• Electricity or “current” is nothing but the movement of
electrons through a conductor, like a wire.
• DC: The electrons flow steadily in a single direction, or
“forward”.
• AC: Electrons keep switching directions, sometimes
going “forward” and then going “backward”
52
Setting the Machine
• https://www.youtube.com/watch?v=4XsllbOLIDo
• http://www.millerwelds.com/resources/calculators/stick_
amperage_calculator.php
53
Striking an Arc
• To begin the SMAW Process, you must first strike an
arc. This can be done using one of the following
techniques:
– Scratch start – scratch the electrode on the base metal like a
match
– Tap Start – tap the rod against the base metal
54
Work Angle
90°
• The work angle is the
angle between the
electrode and the
work as depicted on
the left
• Work angles can vary
depending on the
position the weld is
being made in
55
Travel Angle
20-30°
• Also commonly called
Lead Angle
• The travel (lead)
angle is the angle
between the
electrode and the
plane perpendicular
to the weld axis
56
Arc Length
• After striking the arc, maintain a 1/8” distance
between the electrode and the workpiece
– If the arc length becomes too short, the electrode will
get stuck to the workpiece or ‘short out’
– If the arc length becomes too long; spatter, undercut,
and porosity can occur
– A proper arc length will produce a crackling sound
like bacon frying.
Arc Length = 1/8”
57
Travel Speed
• The travel speed is the
speed at which the
electrode moves along
the base material while
welding
– Too fast of a travel speed
results in a ropey or
convex weld
– Too slow of a travel
speed results in a wide
weld with an excessive
metal deposit
End of Weld
The travel speed impacts the
shape of the bead.
58
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
59
Restarting a Bead
• Here is the proper technique for restarting a weld:
1. Strike Arc Here
2. Move Electrode
to Crown of Crater
3. Resume Forward
Travel
60
Cleaning
• Slag must be removed after completing the bead, prior
to welding over a bead, and before painting.
• If slag is not removed before restarting a weld or before
welding over a bead, the resulting weld will have slag
inclusions.
– Slag inclusions: Are pieces of slag trapped, or included, in the
weld.
• Remove slag with a wire brush or chipping hammer.
61
Joint Designs
• The five basic joint designs are:
–
–
–
–
–
Butt
Lap
Corner
T-joint
Edge
62
Joint Designs
63
SMAW Safety
• Fumes and Gases can be dangerous
– Keep your head out of the fumes
– Use enough ventilation, exhaust at the arc, or both, to keep
fumes and gases from your breathing zone and the general area
– The SMAW process can withstand wind and exhaust near the arc
from ventilation equipment
• Electric Shock can kill – to receive a shock your body must touch
the electrode and work or ground at the same time
– Do not touch the electrode or metal parts of the electrode holder
with skin or wet clothing
• Arc Rays can injure eyes and skin - Choose correct filter shade.
64
Center-Stanton Agriculture
Welding
• Get started working right away when class starts.
• Change into your welding clothes quickly.
– If you forget them you will receive a zero for the day and receive
a paper assignment.
• Last 10 minutes is used for cleaning.
– You MUST clean the entire time.
– Welding stations and work areas must be kept clean.
• Do NOT throw metal and electrodes in the garbage.
• Make sure all welding machines are turned off.
• NEVER leave hot metal lying around.
65
Advantages of SMAW
•
•
•
•
Low initial cost
Portable
Easy to use outdoors
All position
capabilities
• Easy to change
between many base
materials
What safety precautions should
be taken by these welders?
66
Limitations of SMAW
• Lower consumable
efficiency
• Difficult to weld very
thin materials
• Frequent restarts
• Lower operating factor
• Higher operator skill
required for SMAW
than some other
processes
Building a barge in a large shipyard
67
Troubleshooting
Welds
68
Weld flaws and defects
• Completed welds may have a variety of flaws.
• A welder may find the following weld flaws and defects:
–
–
–
–
Poor weld proportions
Undercutting
Lack of penetration
Surface flaws and defects.
69
70
Troubleshooting Welds
A
B
C
D
E
F
G
These welds were cut and etched
with nitric acid to show penetration
71
Lesson Plans
72
SMAW Lesson #1
• Objective: Strike and establish an arc
• Equipment:
– Single Process –
Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
– Multi-Process
 Power MIG 350 MP
• Material:
– Mild Steel Plate 1/8” or thicker
– 1/8” Fleetweld 5P+ (E6010) for DC
or Fleetweld 180 (E6011) for AC
73
SMAW Lesson #2
• Objective: To run a straight bead on flat plate and to fill the crater
• Equipment:
– Single Process Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
– Multi-Process
 Power MIG 350 MP
• Material:
– Mild Steel Plate 3/16” or thicker
– 1/8” Fleetweld 37 (E6013)
Good
Poor
74
SMAW Lesson #4
•
•
Objective: To build a pad
Equipment:
– Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
– Multi-Process
 Power MIG 350 MP
•
Material:
– Mild Steel Plate 3/16” or thicker
– 1/8” Fleetweld 37 (E6013)
75
SMAW Lesson #5
•
•
Objective: To make a fillet weld on a lap joint in the horizontal position (AWS
Position 2F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
2F
Top View
Side View
76
SMAW Lesson #6
•
•
Objective: To make a fillet weld on a tee joint in the horizontal position
(AWS Position 2F)
Equipment:
– Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
– Multi-Process
 Power MIG 350 MP
•
Material:
– Mild Steel Plate - 10 gauge
– 1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
2F
77
SMAW Lesson #7
•
•
Objective: To make a fillet weld on a tee joint in the horizontal position (AWS
Position 2F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Excalibur 7018 (E7018) for DC
or Lincoln 7018AC (E7018) for AC
2F
78
SMAW Lesson #8
•
•
Objective: To make a three pass fillet weld on a tee joint in the horizontal position
(AWS Position 2F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate – ¼”
1/8” Excalibur 7018 (E7018) for DC or
Lincoln 7018AC (E7018) for AC
2F
79
SMAW Lesson #9
•
•
Objective: To make a fillet weld on a lap joint in the vertical position welding down
(AWS Position 3FD)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Fleetweld 37 (E6013)
3FD
80
SMAW Lesson #10
•
•
Objective: To make a fillet weld on a tee joint in the vertical position welding down
(AWS Position 3FD)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
3FD
81
SMAW Lesson #11
•
•
Objective: To make a fillet weld on a lap joint in the overhead position (AWS Position
4F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
4F
82
SMAW Lesson #12
•
•
Objective: To make a fillet weld on a tee joint in the overhead position (AWS
Position 4F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate - 10 gauge
1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
4F
83
SMAW Lesson #13
•
•
Objective: To make a single pass fillet weld on a tee joint in the vertical position
welding up (AWS Position 3F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate – 1/4”
1/8” Fleetweld 5P+ (E6010) for DC or Fleetweld 180 (E6011) for AC
3F
84
SMAW Lesson #14
•
•
Objective: To make a three pass fillet weld on a tee joint in the vertical position
welding up (AWS Position 3F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate – 1/4”
1/8” Fleetweld 5P+ (E6010) for
DC or Fleetweld 180 (E6011) for AC
3F
85
SMAW Lesson #15
•
•
Objective: To make a single pass fillet weld on a tee joint in the vertical position
welding up (AWS Position 3F)
Equipment:
–
–
•
Single Process - Constant Current Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and accessories
Multi-Process
 Power MIG 350 MP
Material:
–
–
Mild Steel Plate – 1/4”
1/8” Excalibur 7018 (E7018) for DC or Lincoln 7018AC (E7018) for AC
3F
86
SMAW Lesson #16
•
•
•
Objective: To make a three pass fillet weld
on a tee joint in the vertical position welding
up (AWS Position 3F)
Equipment:
– Single Process - Constant Current
Power Source
 Idealarc 250 and accessories
 Precision TIG 225 and
accessories
– Multi-Process
 Power MIG 350 MP
Material:
– Mild Steel Plate – 1/4”
– 1/8” Excalibur 7018 (E7018) for DC or
Lincoln 7018AC (E7018) for AC
3F
87
AWS Connection
88
AWS Connection
• The SMAW Welding Unit of study incorporates
the following information taken from the AWS
EG 2.0 requirements:
– Set up for SMAW operations on carbon steel
– Operate SMAW equipment on carbon steel
– Make SMAW fillet welds on carbon steel
89
English, Math, and
Science Connection
90
National Academic Standards
Crosswalk
• The unit, just completed, has covered parts of
academic content listed in the National
Academic Standards as follows:
– NM-PROB.CONN.PK-12.3: Recognizes and applies
mathematics in contexts outside of mathematics.
– NLA-STANDARD 1: Uses the general skills and strategies of
the writing process.
– NLA-STANDARD 7: Uses reading skills and strategies to
understand and interpret a variety of informational texts.
– NS-PHYSICAL SCIENCE: (Experiences) interactions of energy
and matter.
91
SMAW Equipment Set Up
1. Turn power supply on
2. Connect work clamp
3. Select electrode
a. Type
b. Diameter
4. Adjust output
a. Polarity
b. Amperage
6. Insert electrode into electrode
holder
92
SMAW Process Variables
• Settings on the machine
– Polarity : AC, DC+, DC– Amperage Output
• Operator Controlled
Variables
–
–
–
–
Work Angle
Travel Angle
Arc Length
Travel Speed
A straight AC machine will
not have a polarity switch
like this AC/DC machine
93
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