103a-bA Flashcards
To protect yourself from electrical shock when welding you must ensure that all that equipment is properly __________.
Grounded
What are the first two signs of oxygen deficiency?
A) Euphoria
B) Dizziness
What sheet of filter plate do AWS and CSA recommend as the minimum.
A) #2
B) #10
C) #11
D)#14
B) #10
What is the primary function of shielding gas?
To shield the molten weld metal from atmospheric contamination
List the two outputs produced by common welding sources
CC- constant current
CV- constant voltage
Flowmeters control the __________ of shield gas to the gun nozzle
Rate of flow
What should your protective clothing characteristics be when welding with GMAW and why?
Clothing should be dark tightly knit 100% cotton to reduce reflected light radiation, and promote fire resistance.
Is it advisable to weld with any are quoting process under wet weather conditions? explain
If you protect yourself from electrical shock hazards by wearing rubber boots with dry socks, and gloves
Name the two toxic gases that the ultraviolet light from welding will produce.
Phosgene
Ozone
How might using children cast during welding affect air quality?
Shielding gases in sufficient quantities, displace enough air to make the work area oxygen deficient.
Dizziness or euphoria is usually the first time of O2 deficiency.
Take precautions to ensure adequate breathing air is always supplied.
List the six essential equipment components always required to set up a wire feed outfit.
Power source
Wire feeder
Gun and cable assembly
Spooled, filler wire
Shielding gas
Gas control equipment
With three properties are wire feed welding power source ratings based on?
Amperage
Voltage
Duty cycle
What is the most common current that the wire processes use?
A) constant current -CC
B) constant voltage CV-(constant potential)
C) alternating current -AC
D) high frequency -hf
B) constant voltage CV-(constant potential)
A CV Power source increases or decreases the welding current to account for what?
Voltage Fluctuations
The voltage control presets the desired ________ on a CV power source.
a) voltage
b) amperage
c) WFS
d) arc length
d) arc length.
Why is a constant voltage constant speed system preferred over constant current voltage sensing systems
A) smoother arc characteristics, and consistent burn off rate
B) higher disposition rates
C) ark starting properties
D) the ability to have a longer stick out length for visibility
A) smoother arc characteristics, and consistent burn off rate
A CV power source increases or decreases the welding current to account for what?
Voltage fluctuations
The voltage control presets the desired ______ on a CV power source
voltage
amperage
WFS
arc length
Arc length
constant current machine should be equipped with _____ to be used for wire processes?
Variable speed / voltage sensing
Constant Speed
Variable speed / voltage sensing
What is the most common pull feed system?
Spool on the gun
Which system maintains arc length by automatically adjusting the amperage output as the electrode extension changes?
A) constant speed wire feeder
B) voltage sensing wire feeder
C) dual head wire feeder
D) micro processor controlled wire feeder
A) constant speed wire feeder
List the five essential components of a typical air cooled gun
Gun body
Gas diffuser
Contact tube
Nozzle
Cable assembly including conduit & liner
What is the maximum weight you can get in a bulk drum
1000 lbs
How should you store unused wire or open filler metal packaging?
A) keep them covered and away from humid environments
B) loosely set to the side for easy access
C) stacked in a designated area on the floor
D) store all the filler metals so that they are readily available
A) keep them covered and away from a humid environment
List five identification factors that you would find listed on packaging
Classification
Wire size
Spool size
Batch number
Manufacturer
What are the five basic modes of metal transfer in wire feed processes?
Short-circuiting transfer
Globular transfer
Spray transfer
Pulsed spray transfer
Modified short circuit transfer
What positions can short circuit metal transfer be used in
A) flat position
B) horizontal position
C) vertical downhill
D) all of the above
D) all of the above
Which mode of metal transfer is avoided with GMAW due to increased spatter and poor weld metal appearance
A) globular
B) short-circuiting
C) spray
D) pulsed spray
A) globular
What positions is spray arc metal transfer most used in
A) flat position only
B) horizontal, and flat position
C) vertical downhill position only
D) all positions
B) horizontal, and flat position
List six operating variables in a wire feed system, the impact welding quality
Inductance
Voltage
Amperage
Polarity
Electrode extension (stick out)
Slope
What does AWS stand for
American Welding Society
What does CSA stand for
Canadian Standards Association
What does the CSA recommend as the lightest shade to use for GMAW processes
Shade #10
List the 6 main components of wire feeding assembly
- Power Source
- Wire feeder compatible with power source
- Electrode Holder (gun) & cable assembly
- spooled filler wire
- Regulator/ flow metre
- cooling system if required
Describe what the Power Source does
The Power Source delivers current to the electrode and work piece to create an arc
Do most wire feed applications use DCRP or DCSP
DCRP
What are the two types of current common power sources might produce?
CC - Constant Current
CV - Constant Voltage
What does CC stand for and what is it equal to
Constant Current = Amperage
When H2O coolant system is being used what may the feeder control contain for operating the shielding gas, flow valve & H20 coolant flow valve?
Solenoids (electric control)
Shielding gasses are used to weld what type of steels using the GMAW, FCAW, MCAW methods?
Low carbon & low alloy steels
What is a shielding gas’s primary purpose?
To protect the molten weld metal from atmospheric contamination.
What are gun & cable assemblies rated by?
Their current carrying capacities.
What factors does the use of a shielding gas affect?
Arc stability
Metal Transfer Modes
Penetration
What is a combo regulator & flowmeter used for?
The reg reduces the gasses source pressure to a constant working pressure, while the flowmeter controls the rate of gas flow to the nozzle.
When is a H20 cooling system used
For high current applications
Most often with fully automatic welders
Who’s standards must welding power sources meet?
NEMA
National Electrical Manufacturers Association
What are the 3 categories power sources are rated by?
Amperage
Voltage
Duty Cycle
A machine is rated for 300 amps and 60% duty cycle.
Calculate the amperage it is rated for.
300 amps x 60% = 180amps
A machine is rated for 300 amps and 60% duty cycle.
How long can it continuously run?
Run 6 min cool for 4 min
(calculations are always based on 10 min increments)
Calculate the duty cycle of a machine that is rated for 300 amps but is ran at 60% of its max load.
300amps x 60% / 100 = duty cycle 1.8
Explain Duty Cycle
How long the machine is running vs idling
What does CV stand for
Constant Voltage
What are the 3 terms that are used interchangeably in regards to power.
CV = CAV=CP
Constant Voltage
Constant Arc Voltage
Constant Potential
What does a CV power source do?
It maintains the Arc Voltage during current stages when the wire short circuits then clears the short circuit smoothly back to the welding arc.
What must be automatically supplied by a CV power source
Amperage- according to the wire feed rate
Why does a CV power source automatically adjust the amperage as the wire feed rate is adjusted
controls the burn off rate
A graph of a CC volt - amp curve described as drooping. Describe the weld and its functional characteristics.
erratic arc
uneven penetration
irregularity shaped weld deposit
A graph of a CV volt - amp curve described as flat. What is its best benefit
It is self correcting and requires less skill to maintain a steady gun to work distance.
When a CV power source is used with a constant speed wire feeder it maintains a nearly constant ________ during short circuit metal transfer.
Voltage
CV machines can be used with what 4 wire processes
GMAW - mig
FACW - Flux core
MCAW - powdered metal core
SAW - submerged arc welding
What are the 2 primary controls on a CV power source?
Wire feed rate
Voltage (arc length)
On a CV power source, if you increase the wire feed rate what else is directly effected?
Amperage
What are the 3 types of wire drive systems?
Push
Pull
Push-Pull
What is the max feed distance of a wire push system?
15ft
On a pull drive wire feed system were is the spool of wire?
On the gun, close to the contact tip
What issue does a pull wire drive system overcome?
wire hangups are frequent when pushing soft wire
Is a Push wire drive system preferred for small or large diameter wire? Hard or soft?
Small & soft
Does a push pull wire drive system work well with soft wire? Y/N
Yes
Depending on manufacturers how far can a push pull wire drive system reach
≤ 50ft
What 3 factors must you consider when choosing a wire feed system?
Type of wire needed
Where are you welding
Size and shape of the structure being welded
What are the 5 main components of a Wire feed control/ drive unit?
Spindle - holds wire
Control unit
Variable speed electric motor
Drive roll assembly
accessories to maintain wire alignment
What are the 2 switches most wire feeders have?
Jog
Purge
What type of power supply does a voltage sensing wire feeder use?
CC
What type of power supply does a constant speed wire feeder use?
CV
If the gun is hooked up to the + on the power source what type of polarity is it?
Reverse Polarity
If the gun is hooked up to the - on the power source what type of polarity is it?
Straight Polarity
What does a voltage sensing wire feeder use to sense the arc voltage?
a pick up lead
What does the drive roll assembly do?
Moves the wire through the cable liner to the gun head
Describe the ideal roll assembly combination of pressure/slip
Enough pressure to feed the wire smoothly, but would slip if a problem occurs in the gun or cable assembly.
Name the 4 Drive rollers
Knurled
Angled
V-Grooved
U- Grooved
Which of the 4 drive roll systems:
used with solid wires
provides 3 point contact
V-Grooved
Which of the 4 drive roll systems:
Used with hollow wires
used for max drive force & min pressure
Knurled
Which of the 4 drive roll systems:
used with solid & soft wires
provides 3 point contact
U-Grooved
How are welding guns rated?
By their current carrying capacity
How are welding guns rated for
0-199 amps generally cooled
Air
How are welding guns rated for
200-750 amps generally cooled
H20
What are the 6 main Air cooled gun components?
Gun Body
Gas diffuser
contact tube/tip
nozzle
cable assembly
conduit and liner
What are contact tubes/tips usually made of?
copper or copper alloys
what is the main function of the contact tube/ tip?
To transfer the electrical current from the electrode to the wire to the weld zone
What is the function of the nozzle?
Directs the shielding gas onto the weld zone
What does using shielding gas prevent?
atmospheric contamination
What is often inside the nozzle?
A sleeve of insulating material to prevent contact between the nozzle and the wire.
What functions does the cable assembly fufill?
a flexible means of transmitting the welding current, shielding gasses & filler metals to the weld zone.
Explain the term helical
wound up like a spring
What type of wire is a helical SS or mild steel liner recommended for.
Hard wire
Soft wire
Hard wires
What are the liners made of that are meant for soft wires like AL and Cu.
Nylon
teflon
plastic
As they are smooth and help the wire feed smoothly
Explain how to measure cast.
The circles diameter of one loop of wire (max 10’) when cut from the spool & laid out unrestrained on a flat surface
Define: Consumable Electrode Wire
Filler wire that is consumed into the molten weld
Define Composite Electrode
Multi component filler metal electrodes eg stranded wire, hollow tubes, covered wire MCAW uses these
Define Flux
a material that prevents formation of oxides or other undesirable substances in the molten metal or on the solid metal surface
Does Flux remove oxides and other undesirable substances from the weld?
Yes it dissolves them or facilitates the removal of them from the weld zone.
Define Helix
A corkscrew effect exhibited by a ring of filler wire when on a flat surface unrestrained
- if both ends lie flat - no helix
- if even 1 end is raised
- the distance from the surface its sitting on to the raised end is the helix
Who is ISO
International Organization for Standardization
Define Mechanical Property
a metals ability to resist an applied force.
What are 3 mechanical Properties
tensile strength
ductility
fracture toughness
Define Cast
When wire is spun onto a spool has a permanent deformation known as cast
If you had a hard and a soft wire which would have less cast?
The Hard wire
If wire has to much cast what problems does that cause (2)
Extreme drag in the liner/ contact tip.
may cause wire feed issues
or unstable arc
What is helix?
the natural twisting of the wire as it is being formed. The helix measurement is the distance between 2 unrestrained loops
what effect causes wire to wonder and develop an unstable arc?
the corkscrew effect
Name 7 considerations that affect your choice of filler wire
- Base metal type
- shielding gas
- welding position
- base metal condition
- base metal chemistry
6.type of metal transfer - service requirements
Name 4 weld factors. How many factors can you change before it affects the mechanical and physical properties of a weld?
- Electrode Size
- Current
- Shielding Gas
- Base Metal Composition
B. it only takes changing 1
What are 3 common deoxidizers
Silicon
Manganese
Aluminium
What are 5 considerations when choosing wire size.
- Smaller the diameter the higher the melting rate.
- the smaller the wire the deeper the penetration
- Larger wire deposits wider beads
- Wire size can increase with the base material thickness
-Welding position
What must manufacturers have on their packaging ?
Manufacturer Name
Classification
Wire type
Spool Size
Batch #
What 3 testing requirements must filler metals for GMAW meet?
Chemical analysis
Tensile Strength
Impact Values
What are 3 things you are protecting your filler wire from when storing?
Moisture
Hydrocarbins
Extreme Temp Changes
Explain Metal Transfer Mode
how the metal moves across the arc from the electrode to the weld zone
What 5 factors determines the mode of metal transfer
- Welding current
- Filler wire dia.
- Arc Length (voltage)
- type of shielding gas
- Position of welding
What are 4 types of metal transfer?
Globular transfer
Spray Arc transfer
Pulsed Spray Arc transfer
Short circuit transfer
modified short circuit transfer
Short circuiting Transfer; what is its key advantage over the other transfer types.
it has low heat input and therefore min distortion. & can be used on light gauge metals or fill wide gaps
Short circuiting Transfer; what is the range of arc volts used for this process
12-22 arc volts
Describe 3 things about Short Circuiting Transfer;
- can be used in all positions
- usually lower current and specific voltage
- separated by a magnetic field using the pinch effect
Why is globular transfer avoided for GMAW
Spatter problems and poor weld appearance
What is the range of arc-volts used for Globular transfer
22-26 arc-volts
What polarity is used for Spray Transfer
DCEP - Direct Curent Electrode Positive
What percentage of Argon should be used with Spray Transfer?
≥85%
When the current is increased beyond its critical value what is this current called
Transition current
With Spray Transfer, what is the term that describes; when the droplets spray inline with the axis of the electrode
Axial Spray
With Spray Transfer. when the arc is on all the time what do you hear to tell you conditions are correct?
A smooth hissing sound
What range of arc volts are used for Spray Arc Transfer?
26-35arc volts
If shielding gas is < 85% argon will the transfer mode change from globular to spray?
No
What mode is mostly used for flat/horizontal & produces the least amt of spatter?
Spray Transfer
Does Spray transfer have High or Low metal disposition rates?
High
What arc transfer mode is a variation of the Spray Transfer Mode?
Pulsed Spray Transfer Mode
Using the Pulsed Spray Transfer Mode;
1. High or Low heat input
2. More or Less distortion
Low heat input = less distortion
What welding Method commonly uses Pulsed Spray Transfer Mode
MCAW
FCAW
SAW
MCAW
What does the low background current in Pulsed Spray Arc Transfer do?
Preheats the wire & maintains the arc.
Why in pulsed Spray Arc Transfer is the pulse of welding current higher than that needed for Spray Arc Transfer?
To obtain metal deposit, flow and penetration
What type of power source is used for Pulsed Spray Arc Transfer? Why?
Inverters
- capable of fast response times & accurate current control
What are 3 characteristics of Modified Short Circuit Transfer
- has no voltage control knob
- heat generated in the weld is reduced
- metal transfer process is regulated precisely
- arc inputs only heat into the material for short periods
What are 6 variables when choosing a wire feeder
- Voltage
- Amperage
- Slope
- Polarity
- Electrode Extension (stick out)
- Inductance
Describe Voltage
the force that overcomes resistance to allow amperage to flow
How is the arc length measured?
From the end of the electrode wire to the weld puddle
What weld characteristic does voltage control
Puddle fluidity
Higher Voltage = what 3 changes of weld characteristics
Wider weld
flatter bead
less penetration
Describe Amperage
the amount of current flow
What weld characteristic does amperage affect
penetration & burnout rate
On a CV power source, when you adjust the wire feed speed what else are you automatically adjusting?
The output amperage
To use a wire feed process with a CC power source what additional unit will you need
voltage sensing wire process
(suitcase welder)
With DC power do you have access to
a. + polarity
b. - polarity
c. + & - polarity
c. + & - polarity
For straight polarity is the electrode hooked up to the + or -?
negative -
For positive polarity is the electrode hooked up to the + or -?
Positive +
With DC which way does the current flow?
- to +
+ to -
From - to +
With GMAW what fraction of the heat is associated with the - side of the welding circuit.
2/3
What are 3 characteristics of using DCEP with GMAW, FCAW, MCAW or SAW
- 2/3 the energy is in the base metal
- electrode burns off cooler allows for slower welding speeds
- narrow metal flow unless the arc is lengthened
- penetration is deeper especially with shorter arc length
What polarity is used with FCAW when using self shielding wire?
DCEP or DCEN
DCEN
2/3 the energy is in the base metal
Electrode burns off hotter = faster welding speeds
Why is AC current not used with most wire feed processes
due to the difficulties with arc stability
Describe Electrode extension and another term for it.
The distance between the end of the contact tip and the end of the unmelted electrode wire.
(Stickout)
What are the 2 effects the change in stick out has.
Increased extension = decreased welding current
Decreased extension increases the current.
How much stick out is generally used in short circuiting metal transfer
1/4” to 3/8”
Describe Slope (Choke)
To limit the short circuiting current so spatter reduces the number of short circuits between the wire and work piece are cleared
(limits how much the machine can rev before being thrown into gear)
What is Inductance
how quick the machine responds to the currents rise and fall
Why is inductance essential to short circuiting transfer
in influences arc on time and decreases the # of short circuits per second
If you increase the inductance what else is effected
increases puddle fluidity
improved penetration
makes bead flatter and smoother
reduces spatter
Is this statement correct;
low inductance = hard starts
Increased inductance =more arc on time
Yes
What does open current voltage describe
when the machine is running but not welding.
