Wire Feed Welding Equipment Power Sources

Question 1

What colour should your protective clothing be when welding with GMAW and why?

Answer 1

clothing should be dark to reduce reflected light radiation

Question 2

Is it advisable to weld with any arc welding process under wet weather conditions? explain.

Answer 2

when you are exposed to wet weather conditions or standing on wet surfaces, protect yourself from electrical shock hazards by wearing rubber boots with dry socks and rubber gloves

Question 3

The use of shielding gases when using wire feed processes increases the need for good:

a) lighting
b) ventilation
c) heat shielding
d) eye protection

Answer 3

b) ventilation

Question 4

Name 2 toxic gases that can be created from the ultraviolet light produced from welding.

Answer 4

ozone

phosgene gas

Question 5

How can air quality be affected when welding with a process that uses a shielding gas?

Answer 5

shielding gases in sufficient qualities displace enough air to render the work area oxygen deficient. Dizziness or euphoria is usually the first sign of oxygen deficiency. Precautions must always be taken to ensure adequate breathing air is supplied.

Question 6

High Ultraviolet radiation emissions form an open arc can cause atmospheric oxygen in the vicinity of the arc to convert to:

a) ozone
b) carbon monoxide
c) carbon dioxide
d) argon

Answer 6

a)ozone

Question 7

A potential source of poisonous chemical fumes when welding is:

a) inert shielding gases
b) chlorinated degreasing solvents
c) carbon dioxide extinguishers
d) anti-spatter novel sprays

Answer 7

b) chlorinated degreasing solvents

Question 8

Define and describe the GMAW process in detail

Answer 8

GMAW is an arc welding process that uses an arc between a continuous filler metal electrode and the weld pool. The process uses shielding gas from an externally supplied source.

Question 9

The gas metal arc welding process is also known as:

a) MIG welding
b) Flux cored arc welding
c) self-shielding process
d) shielded metal arc welding

Answer 9

a) MIG welding

Question 10

GMAW is recommended for use on which of the following metals:
a) stainless steel
b) aluminum
c) copper alloys
d_  carbon and low alloy steels
e) all of the above

Answer 10

e) all of the above

Question 11

Describe the operating principles of FCAW.

Answer 11

FCAW uses an arc established between a continuously fed consumable electrode and the work piece. Appropriate settings made by the operator maintain a constant burn-off rate of the wire electrode. Depending on the power source and wire drive system used, the arc length is maintained automatically . Shielding gas can be externally applied and/or obtained from a flux contained within the hollow electrode core. (depending on the type of flux cored wire used).

Question 12

Self-shielded FCAW uses shielding gas generated from:

a) the base metal
b) an external source
c) the flux
d) a paste flu applied to the base metal before welding

Answer 12

c) the flux

Question 13

What is the electrode extension range for self-shielded FCAW

Answer 13

For self-shielded electrodes, extensions range from 19m to 95mm (3.4” - 3 3/4”)

Question 14

The MCAW process uses the same equipment as which process?

a) SMAW
b) GTAW
c) FCAW
d) OAW

Answer 14

c) FCAW

Question 15

List the basic equipment components always required for the set-up of a wire feed outfit

Answer 15

a) power source
b) wire feeder
c) gun and cable assembly
d) spooled filler wire
e) shielding gas and
f) gas control equipment

Question 16

How are wire feed guns rated?

a) by voltage-carrying capacity
b) by physical size
c) by current-carrying capacity
d) by shielding gas flow rate

Answer 16

c) by current-carrying capacity

Question 17

The major factor in choosing between an air-cooled or a water-cooled gun is the required:

a) shielding gas
b) current/voltage
c) joint design
d) base metal alloy

Answer 17

b) current/voltage

Question 18

Welding power sources designed only for wire feed welding can be used for shielded metal arc welding (SMAW).
True - or - False

Answer 18

False

Question 19

GMAW may be used in the semi-automatic or automatic operation modes.
True - or - False

Answer 19

True

Question 20

What type of welding power source is most often used for GMAW?

Answer 20

constant voltage

Question 21

Constant voltage (CV) machines produce a:

a) drooping volt-amp curve
b) rising volt-amp curve
c) Relatively flat volt-amp curve
d) constantly changing volt-amp curve

Answer 21

c) Relatively flat volt-amp curve

Question 22

The power source best suited for the short-circuit mode of metal transfer is a:

a) rising arc voltage power source
b) constant voltage power source
c) constant current power source
d) constant amperage power source

Answer 22

b) constant voltage power source

Question 23

What type of volt-amp curve does a constant current machine produce

a) flat
b) variable
c) rising
d) drooping

Answer 23

d) drooping

Question 24

A welding machine that produces an almost horizontal output slope is a:

a) constant current machine
b) constant voltage machine
c) rising arc voltage machine
d) high amperage potential welding machine

Answer 24

b) constant voltage machine

Question 25

List 3 advantages and 3 disadvantages of GMAW.

Answer 25

Advantages:
lower skill requirements than SMAW
excellent for light gauge metals
good arc control when working with poor fit-ups
less heat input means less distortion than SMAW
high production rates
no slag to remove, little or no post weld clean-up

Disadvantages:
special equipment required resulting in higher initial cost
equipment requires more maintenance and down time
lack of fusion can be a problem
cannot be used outdoors or in draft locations
high radiant energy requires protetction for the welder and others in the area
wire feeder must be in close proximity to welding.

Question 26

One of the main advantages of metal core wires is:

a) lower cost than flux core wires
b) no external shielding gas is required
c) designed for use on conventional CC power sources
d) high deposition rates

Answer 26

d) high deposition rates

Question 27

List 3 advantages and 3 disadvantages of FCAW.

Answer 27

Advantages:
The deposition rate is up to 4 times greater than with SMAW
There is high operating factor, so it is easily mechanized
the visible arc is easy to use
the weld metal deposits are high quality.
Disadvantages:
The equipment is more expensive to purchase than that needed for SMAW
More smoke and fumes are generated, which require suitable exhaust removal equipment
the wire feeder must be in close proximity to the welding
equipment is more complex than for SMAW so it requires more maintenance.

Question 28

The powder in a MCAW wire consists mostly of:

a) flux
b) metal
c) slag formers
d) arc stabilizers

Answer 28

b) metal