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Shop/PD > Mild Steel GMAW > Flashcards

Mild Steel GMAW Flashcards

1
Q

What is GMAW how does it work

A

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

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2
Q

What is used in mig to prevent atmospheric contamination?

A

Shielding gas

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3
Q

What type of machine setting does GMAW use

A

Direct current, electrode positive

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4
Q

3 types of metal transfer

A

Short circuit, globular transfer, and spray transfer

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5
Q

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

A

FCAW flux core arc welding

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6
Q

3 types of wire drive systems

A

Push, pull, push and pull

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7
Q

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

A

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

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8
Q

Main function of contact tube

A

Transfer electrical current to electrode and direct wire to weld zone

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9
Q

Directs shielding gas on to weld zone?

A

The nozzle

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10
Q

Main purpose of regulator

A

Reduce source pressure to working pressure

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11
Q

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

A

A gas solenoid valve

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12
Q

How are cylinders identified and stored

A

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

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13
Q

What does a metal rupture disk do.

A

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

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14
Q

Flow rate for CO² and argon/ CO²

A

20 cfh

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15
Q

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

A

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

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16
Q

Another name for stickout

A

Electrode extenion or electrical stickout

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17
Q

Another name for electrode inclination what is it.

A

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

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18
Q

Two terms for the inclination when welding

A

Forehand (push angle)
Or backhand (pull angle)

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19
Q

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

A

Travel speed

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20
Q

Poor work lead connection can lead to what?

A

Unstable arc

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21
Q

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

A

Stubbing

22
Q

Another name for bird nesting? what can cause it.

A

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

23
Q

5 basic joints in gmaw

A

Butt, lap, edge, corner, grooved

24
Q

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

A

Lap

25
Q

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

A

Porosity

26
Q

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

A

Burn through

27
Q

Most serious weld defect that can lead to complete weld failure

A

Cracking

28
Q

What is undercut

A

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

29
Q

What is porosity

A

Pockets of gas entrapped within weld metal

30
Q

What is lack of fusion

A

Metals not melting together, no coalesce of metal.

31
Q

What is lack of penetration

A

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

32
Q

What are whiskers

A

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

33
Q

What are inclusions, also known as?

A

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

34
Q

What effect does changing wire speed have on amperage or voltage

A

Increased wire speed =Increased amperage, voltage not affected

35
Q

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

A

Work (transverse) and travel (
longitudinal)

36
Q

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

A

Welding symbols

37
Q

What causes porosity

A

Contamination

38
Q

What defect is GMAW specific

A

Whiskers

39
Q

Most dangerous type of light ray emmited by welding

A

Infrared rays

40
Q

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

A

99%

41
Q

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

A

Leather, wool or tweed, cotton drills or denim

42
Q

Recommended lense level for gmaw

A

9 to 13

43
Q

Maximum safe working pressure of acetylene

A

15psi

44
Q

Stubbing is when

A

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

45
Q

What is the pinch effect

A

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

46
Q

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

A

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

47
Q

What is a push system

A

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

48
Q

What is a pull system

A

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

49
Q

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

A

Copper or copper alloy. Wire size specific.

50
Q

Purpose of cable assemblies.

A

Used to join power source to the gun

51
Q

Can you transfer gas from one cylinder to another.

A

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

52
Q

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

A

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

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