Welding

Question 1

What does GMAW stand for and what is it sometimes called?

Answer 1

Gas Metal Arc Welding, sometimes called MIG

Question 2

What is the purpose of the shielding gas?

Answer 2

It protects the molten metal from coming into contact with the surrounding air.

Question 3

How much slag is produced in this welding process?

Answer 3

Virtually slag free

Question 4

What was this process first developed for?

Answer 4

To speed up the production welding of heavy aluminum plate.

Question 5

What type of shielding gas was used when welding aluminum

Answer 5

An inert gas either argon or helium.

Question 6

Why is MIG no longer the correct term for this process?

Answer 6

Because we no loner use inert gas. We now use carbon dioxide and argon.

Question 7

What does the Arc gap refer to?

Answer 7

The distance between the electrode and the metal

Question 8

What maintains the arc gap with this process?

Answer 8

The machine automatically maintains a constant arc gap.

Question 9

What three things does the equipment have to do in this process?

Answer 9

Maintain the arc, Feed the wire and supply shielding gas.

Question 10

What three things does the person welding have to control during this process?

Answer 10

Gun position, direction, travel speed

Question 11

List the equipment for GMAW

Answer 11

Power source, Wire feed unit, Gun assembly, Ground connection and high-pressure tank

Question 12

What type of power source is required for GMAW?

Answer 12

CV/DC Constant Voltage Direct Current

Question 13

What polarity is used for welding all carbon steel?

Answer 13

Direct Current Electrode Positive

Question 14

What does the spring loaded nut on the end of the wire roll spindle do?

Answer 14

Ensures that the spool stops when the drive rolls stop.

Question 15

What are the drive rolls specifically designed for?

Answer 15

For specific wire sizes

Question 16

How tight should the drive rolls be tightened?

Answer 16

Just enough to keep the wire from slipping

Question 17

What parts are found on the end of the gun?

Answer 17

Diffuser, Contact tip, and nozzle

Question 18

Why do contact tips come in different sizes?

Answer 18

To match different wire diameters

Question 19

How far should the contact tip protrude beyond the end of the nozzle?

Answer 19

Should be nearly flush

Question 20

When feeding the wire through what should be done to the gun

Answer 20

Remove the nozzle and tip

Question 21

What should be done to the cylinder when transporting it?

Answer 21

It should be chained up and always use the protective valve cover

Question 22

What does the flowmeter do?

Answer 22

Regulates the amount of gas flow

Question 23

What is gas flow measured in?

Answer 23

Cubic feet per hour

Question 24

Where should you stand when opening the cylinder

Answer 24

Behind the valve, opposite side

Question 25

How should the cylinder be opened?

Answer 25

Crack it slowly and then open it all the way.

Question 26

How do you get an accurate reading when setting the gas flow?

Answer 26

Hold the trigger down while setting it.

Question 27

What can be used as an average gas flow setting?

Answer 27

Around 20 cubic feet per hour

Question 28

What can excessive gas flow do to the weld puddle?

Answer 28

May have a cooling effect

Question 29

What will too little flow do to the weld deposit?

Answer 29

Gas pockets called porosity will form

Question 30

What should always be done to the wire before making a weld?

Answer 30

Snip off the excess wire

Question 31

What should the nozzle be checked for before making a weld?

Answer 31

Splatter built up

Question 32

What can excessive splatter cause on the contact tip?

Answer 32

Pinched wire causing wire to become out of line and bunch up in the machine

Question 33

What is a common filler wire that can be used with GMAW?

Answer 33

ER70S-6

Question 34

What us meant by wire tensile strength?

Answer 34

The force it takes to pull it apart

Question 35

How are filler wires sized?

Answer 35

.023, .030, .035, .040

Question 36

What type of shielding gas is used for welding carbon steels?

Answer 36

A blend of carbon dioxide and argon

Question 37

What is the function of the shielding gas?

Answer 37

To cover the molten weld and keep it from coming into contact with oxygen and nitrogen in the air

Question 38

What does Carbon Dioxide do to the arc?

Answer 38

Creates a wide arc stream

Question 39

What does pure Argon do to the arc?

Answer 39

Produces a narrow and dense stream

Question 40

Why is Carbon Dioxide and Argon blended for welding carbon steels?

Answer 40

To provide a sufficient arc energy at lower voltages

Question 41

Why is oxygen sometimes added to gas blends?

Answer 41

Because higher argon content reduces the energy

Question 42

What is a common gas blend for all position welding of carbon steels?

Answer 42

75% Argon 25% CO2

Question 43

What three things happen when the welding gun trigger is pulled?

Answer 43

Current becomes available, a solenoid opens the valve for shielding gas, drive rolls feed the wire

Question 44

What type of metal transfer will take place at lower voltages?

Answer 44

Short circuit transfer

Question 45

What positions can you weld in with lower voltage settings?

Answer 45

All positions flat, horizontal, vertical and overhead

Question 46

What voltage will change the transfer mode?

Answer 46

Around 22 Volts

Question 47

What transfer mode takes place at a higher than 22 Voltage setting?

Answer 47

Globular Transfer

Question 48

What is the undesirable byproduct of a higher voltage transfer mode?

Answer 48

Excessive weld splatter

Question 49

What transfer mode will take place at very high voltage with a rich argon gas blend?

Answer 49

Spray transfer

Question 50

What can you do if the arc sputters at the start?

Answer 50

Check the ground connection

Question 51

What 4 things is the molten puddle controlled by?

Answer 51

The distance the gun is held from the metal Where the arc hits the puddle The angle of the gun The travel speed

Question 52

What term is used to describe how much wire protrudes from the end of the tip?

Answer 52

Electrode Extension

Question 53

What is recommended wire protrusion when welding?

Answer 53

1/4" to 3/8"

Question 54

What will longer protrusion do to the arc heat?

Answer 54

Allow the wire to preheat

Question 55

Where should the gun be held to provide a good hot start

Answer 55

Close to the work

Question 56

Where should the wire be directed when welding?

Answer 56

At the leading edge of the molten puddle