Welding Flashcards
What does GMAW
Gas metal arc welding
What is DCEP
Direct current, electrode positive
What is the “mode of metal transfer”?
The way that the weld metal transfers across the arc from the end of the electrode to the weld zone
What are the 3 different basic modes of metal transfer?
- short-circuiting transfer
- globular transfer
- spray transfer
What are the 5 factors that determine the mode of metal transfer?
- weld current
- filler wire diameter
- arc length (heat control)
- type of shielding
- position of welding
Which type of welding produces the least amount of spatter?
Spray arc welding (spray transfer)
What kind of welding occurs when there is a 85% argon or higher?
Spray transfer
What is the transition current?
?
Which has a higher arc voltage:
Spray transfer or short circuit transfer?
Spray transfer?
What is globular transfer?
When the metal passes through an open arc in the for of large globules
What is the current setting for globular transfer?
Between short-circuiting and spray transfer
What size wire is used in short-circuiting metal transfer?
0.023-0.045”
How does short-circuiting metal transfer work?
The filler wire makes Direct contact with the base metal, creating a short-circuit in the arc. It then melts off and melts into the base metal
What are the advantages of short-circuiting welding?
- Minimum distortion due to low heat
- Ideal for joining light gauge metals
- And for fit-ups with wide gaps
What is most common power source used for most GMAW applications?
DCEP- direct current, electrode positive
What is AWS?
American welding society
What is the primary function of the shielding gas?
To shield the molten weld metal from atmospheric contamination
What gas is used for:
Aluminum:?
Carbon and low-alloy steels?
Range from argon or helium.
Steel- mixture of Argon and CO2
What is the purpose of the regulator?
It’s responsible for reducing the gas source pressure to a constant working pressure
What does the flow meter do?
They are calibrated to indicate a volumetric flow rate in L/min or CFM (cubic feet per minute)
What is the pressure of a full cylinder at room temp?
Approx. 2000 psi
What should you do before installing the regulator onto the tank?
Should crack the cylinder valve for a second to blow any dirt or dust away
What is the recommended rate of flow for the gas?
15-35 CFH
What are considered Inert gas?
Argon, helium, and CO2
What should you mark on an empty bottle?
“MT” with a soapstone
What is the electrode angle refer to?
And what should it be?
Refers to the position of the wire in relation to the included joint angle
Should be on half of the included joint angle
What is it called when you fail to fill the parent metal after melting it away?
Undercut
AWS-ER-70S-6
What does each letter stand for?
AWS- American welding society?
E- designated Electric welding
R-designated it as a filler rod
70-tensile strength in thousands of pounds per inch
S- designates solid wire (T is for flux core or tubular wire)
6- designated wire characteristics (6: all positions)
What is the electrode that we use in the shop
AWS-ER-70S-6
What is electrode inclination?
It’s the position of the electrode to the work piece in relation to the direction of travel
Which type of weld produces a flatter bead shape with less penetration?
A forehand inclination
What type of inclination creates a narrower bead with a higher crown?
A backhand inclination
What is the weld with the maximum penetration?
A 15-20 degree backhand inclination?
What is electrode extension and what is recommended?
Distance from the end of the contact tube to the end of the wire?
3-8”
What is the recommended electrode angle for a flat butt weld?
90 degrees
What is the recommended placement for the nozzle end?
Flush with the contact tube
What may be the issue if you aren’t getting a good weld and lots of splatter?
Contact tip is off centre so it changes the pattern of the shielding gas flow
What is a cause of porosity and poor quality welds?
Splatter build up on the nozzle creating gas flow turbulence
What is used to direct the shielding gas onto the weld zone?
The nozzle
What can a bad ground cause?
Can cause an unstable arc
What should be done before welding on any vehicle or trailer?
Disconnect all batteries
What is it called when the electrode comes in contact with the base metal and fails to start and arc immediately?
What can be the causes for it?
Called “stubbing” Can be caused by: excessive wire feed speed, Low arc voltage or Heavily scaled base metals
When should the conduit liner be cleaned of any wire?
Every time you change the spool
What can a badly worn or dirty contact tip cause?
Arc hunting
What is the cause of a porosity, black, saggy weld
Lack of shielding gas
What refers to the pockets of gas entrapped within the weld metal?
Porosity
What happens when you carry a large bead with slow travel speed where the wire rides onto of the puddle?
Cold starts! It will not penetrate properly
What is the “root”
It is the bottom of your weld with the most penetration
What is produced when welding galvanized metals?
Zinc oxide
What shade of welding tint in minimum and what is suggested?
10 is the minimum but CSA+AWS suggest a #11
What kind of clothing should be worn when welding?
100% cotton Dark colour to reduce reflection Tight knit Gauntlet style gloves Steel toed, leather safety boots Welding mask
What kind of ventilation should you have when welding?
A low-velocity suction hood or something that will not disturb the welding gas
