103a-bA / exam Jan 9 80% 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 __________ 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.
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
Arc length
What my second constant current machine be equipped with to be used for wire processes?
Voltage sensing unit
What is the most common pole feed system?
Spool on the gun
Which system maintains our 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 position position 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 that are frequent when pushing soft wire
Is a Push wire drive system preferred for small or large diameter wire? Hard or soft?
Small & soft