Mild Steel GMAW

Question 1

What is GMAW how does it work

Answer 1

Gas metal arc welding, Joins metal by heating them with a electric arc from a continuously fed metal filler

Question 2

What is used in mig to prevent atmospheric contamination?

Answer 2

Shielding gas

Question 3

What type of machine setting does GMAW use

Answer 3

Direct current, electrode positive

Question 4

3 types of metal transfer

Answer 4

Short circuit, globular transfer, and spray transfer

Question 5

What kind of welding contains a flux that generates shielding for field fabrication

Answer 5

FCAW flux core arc welding

Question 6

3 types of wire drive systems

Answer 6

Push, pull, push and pull

Question 7

Electrode holders and cable assemblies carry what? Also called what?

Answer 7

Welding current, shielding gas, control switch, and coolant also called guns

Question 8

Main function of contact tube

Answer 8

Transfer electrical current to electrode and direct wire to weld zone

Question 9

Directs shielding gas on to weld zone?

Answer 9

The nozzle

Question 10

Main purpose of regulator

Answer 10

Reduce source pressure to working pressure

Question 11

What controls the rate of flow of the shielding gas to gun nozzle

Answer 11

A gas solenoid valve

Question 12

How are cylinders identified and stored

Answer 12

Clearly labeled with contents and whmis. They are to be stored outside or well ventilated area upright and secured.

Question 13

What does a metal rupture disk do.

Answer 13

A safety device on cylinders that, if pressure becomes excessive, will burst, allowing a controlled release of gas

Question 14

Flow rate for CO² and argon/ CO²

Answer 14

20 cfh

Question 15

What can result if flow rate is to high or to low

Answer 15

If it is too low, there is a lack of gas coverage
If too high, there can be turbulence
Both lead to porosity

Question 16

Another name for stickout

Answer 16

Electrode extenion or electrical stickout

Question 17

Another name for electrode inclination what is it.

Answer 17

Work angle, the position of the electrode to the work piece in relation to the direction of travel

Question 18

Two terms for the inclination when welding

Answer 18

Forehand (push angle)
Or backhand (pull angle)

Question 19

Rate that welding moves in a direction. Measured in mms or ipm

Answer 19

Travel speed

Question 20

Poor work lead connection can lead to what?

Answer 20

Unstable arc

Question 21

What occurs when electrodes comes in contact with base metal and an erratic arc is produced

Answer 21

Stubbing

Question 22

Another name for bird nesting? what can cause it.

Answer 22

Wire pile up, plugged or misaligned conduit liner
Sharp bends in cable assembly
Weld splatter plugs end of co tact tube
Electrode wire stubs and sticks to base metal
Wire welds to contact tip

Question 23

5 basic joints in gmaw

Answer 23

Butt, lap, edge, corner, grooved

Question 24

What type of joint uses fillet weld as there’s less need for weld metal penetration

Answer 24

Lap

Question 25

Most common type of weld defect caused by reaction to atmosphere.

Answer 25

Porosity

Question 26

What can happen if current is set to high and travel speed is to low

Answer 26

Burn through

Question 27

Most serious weld defect that can lead to complete weld failure

Answer 27

Cracking

Question 28

What is undercut

Answer 28

The melting away of the parent metal and failing to fill it back in with weld metal

Question 29

What is porosity

Answer 29

Pockets of gas entrapped within weld metal

Question 30

What is lack of fusion

Answer 30

Metals not melting together, no coalesce of metal.

Question 31

What is lack of penetration

Answer 31

The failure to melt into the surface or root edges of a joint

Question 32

What are whiskers

Answer 32

Lengths of unmelted electrode wires welded to and protruding from the root

Question 33

What are inclusions, also known as?

Answer 33

Small pockets of non metallic elements entrapped in the weld zone. Wagon tracks or slag inclusions

Question 34

What effect does changing wire speed have on amperage or voltage

Answer 34

Increased wire speed =Increased amperage, voltage not affected

Question 35

What are the two different angles involved in welding regarding work angles

Answer 35

Work (transverse) and travel ( longitudinal)

Question 36

What is used to indicate weld type on a blue print?

Answer 36

Welding symbols

Question 37

What causes porosity

Answer 37

Contamination

Question 38

What defect is GMAW specific

Answer 38

Whiskers

Question 39

Most dangerous type of light ray emmited by welding

Answer 39

Infrared rays

Question 40

Welding lenses will protect your eyes from ____ of harmful light ray

Answer 40

99%

Question 41

3 types of clothing in order from best to order for welding protection

Answer 41

Leather, wool or tweed, cotton drills or denim

Question 42

Recommended lense level for gmaw

Answer 42

9 to 13

Question 43

Maximum safe working pressure of acetylene

Answer 43

15psi

Question 44

Stubbing is when

Answer 44

Electrode comes in contact with base metal and fails to start an arc immediately. Also pushes gun or welding head away from base metal

Question 45

What is the pinch effect

Answer 45

Molten metal is separated from the end of the filler with a squeezing force created by a magnetic field

Question 46

3 power source machine types for gnaw, all three may produce what?

Answer 46

Motor driven generator, transformer rectifiers, and inverter. May produce either constant current (CC) or constant voltage (CV)

Question 47

What is a push system

Answer 47

Wire is fed by a set of drive rolls located in wire feed unit itself

Question 48

What is a pull system

Answer 48

Have drive rolls mount on the gun itself close to contact tip

Question 49

What is the contact tip usually made of. How are they sized.

Answer 49

Copper or copper alloy. Wire size specific.

Question 50

Purpose of cable assemblies.

Answer 50

Used to join power source to the gun

Question 51

Can you transfer gas from one cylinder to another.

Answer 51

No use, only equipment and fittings designed for the gas delivery system

Question 52

What do flow meters do and what are they calibrated to indicate.

Answer 52

L/min (liters per minute) or CFH cubic feet per hour