CH. 3 GMAW Metal Joining & Cutting Processes Flashcards
1
Q
What are most common inert gases used with GMAW?
What are most common reactive gases used with GMAW?
A
Argon, Helium
Oxygen, Carbon Dioxide
2
Q
Components of typical GMAW equipment include:
A
- Power source & controls
- Power supply
- Work pice lead
- Work piece clamp
- Electrode feed unit
- Electrode supply
- Welding gun
- Shielding gas supply
- Cable assembly
3
Q
What type of power supply does GMAW use?
A
constant voltage
constant potential
power source
CV DC
4
Q
What type of current is used normally when GMAW?
a. DCEP
b. DCEN
A
a. DCEP ( reverse polarity )
5
Q
The use of deoxiders ( manganese, silicon, aluminum ) when GMAW help prevent the formation of what?
A
porosity
6
Q
What are the 4 primary methods of metal transfer in GMAW?
A
- spray transfer
- pulsed-spray transfer
- globular
- short circuit`
7
Q
Name the hottest to the coldest for transfer mechanisms for GMAW.
A
Hottest to Coldest
- Spray
- Pulsed-Spray
- Globular
- Short Circuit
8
Q
Advantages of GMAW
A
- HIGH DEPOSITION RATES
- no slag and almost no splatter
- ability to bridge gaps without burning through
- excellent side fusion and root penetration
- faster production ( no changing spools )
- visibility of process
- Semiautomatic or Machine process
- Welds most alloys
- lowest hydrogen potential of processes used in structural and similar welding since no flux
9
Q
Limitations of GMAW
A
- contamination (porosity) loss of shielding .not good in field
- more complex equipement setup
- INCOMPLETE FUSION due to short circuiting on heavy sections
- arc instability caused by worn liners and contact tips
- unsuitable for windy conditions (lack of shielding)
- more costly ( helium) subject to wind
10
Q
Discontinuities of GMAW
A
porosity incomplete fusion cracking oxides spatter incomplete joint penetration
