120103d Wire Welding Maintenance and Troubleshooting

Question 1

Question: Ideally, a welding power source should be located in:

a) a confined area at floor level
b) an uncluttered, well-ventilated area of the shop
c) the centre area of the shop
d) an unventilated, specially enclosed mezzanine area

Answer 1

Answer: b) an uncluttered, well-ventilated area of the shop.
Explanation: A well-ventilated area is essential for safe and efficient operation of welding power sources to avoid overheating and ensure good air quality.

Question 2

Question: It is important to have wire guides in alignment with drive rolls on the wire drive unit.

a) True
b) False
Explain your answer.

Answer 2

Answer: True; Misalignment can cause unnecessary drag on the wire and lead to feeding difficulties.
Explanation: Proper alignment ensures smooth wire feeding and avoids complications that can arise from wire drag.

Question 3

Question: The installation of a power source must be done in accordance with local ___________ codes and to be completed by ___________ personnel.

Answer 3

Answer: electrical; qualified
Explanation: Following local electrical codes and having qualified personnel for installation ensures safety and compliance with regulations.

Question 4

Question: To obtain an accurate reading from a flowmeter, it must be mounted in the ___________ position.

a) vertical
b) overhead
c) horizontal
d) flat

Answer 4

Answer: a) vertical.
Explanation: A vertical mounting position is necessary for accurate flow readings and proper functioning of the flowmeter.

Question 5

Question: Why must you ensure that all electrical fittings on the welding leads have a tight connection?

Answer 5

Answer: The connections are to be tight to prevent overheating of the cables and power source.
Explanation: Tight connections prevent energy loss and overheating, which can be hazardous and reduce efficiency.

Question 6

Question: The wire spool hub should be adjusted in order to:

a) prevent the unwinding of the wire spool
b) feed freely, yet prevent a backlash of wire when feeding is stopped
c) allow the wire to be removed without restriction
d) run the wire from the bottom of the roll only

Answer 6

Answer: b) feed freely, yet prevent a backlash of wire when feeding is stopped.
Explanation: Proper adjustment of the wire spool hub is crucial for smooth operation and avoiding issues like wire tangling or backlash.

Question 7

Question: How is penetration affected when stickout is increased?

a) Penetration increases
b) Penetration is not affected
c) Penetration decreases
d) Only penetration on groove welds is affected

Answer 7

Answer: c) Penetration decreases.
Explanation: Increasing stickout length reduces the heat and energy focused on the welding spot, leading to decreased penetration.

Question 8

Question: Changing the gun inclination:

a) changes the penetration of the weld.
b) has no effect on the weld.
c) causes the wire to pile up at the drive rolls.
d) causes the wire to feed unevenly.

Answer 8

Answer: a) changes the penetration of the weld.
Explanation: Gun inclination affects the angle and distribution of heat and welding material, thus impacting penetration depth.

Question 9

Question: Describe how GMAW equipment is likely to behave when the contact tip is worn out.

Answer 9

Answer: With extended use, the wire wears the contact tube orifice to an oval shape, causing the wire to slide easier but reducing efficient current transfer. Arcing in the contact tube may occur, fusing the wire or causing erratic wire feeding.
Explanation: A worn-out contact tip affects the wire’s movement and electrical transfer, leading to potential welding issues.

Question 10

Question: Excessive spatter buildup in the gun nozzle can cause:

a) undercut at the weld edges
b) excessive metal flow
c) an increase in stickout
d) inadequate gas coverage

Answer 10

Answer: d) inadequate gas coverage.
Explanation: Spatter buildup can obstruct gas flow, leading to inadequate shielding and potential weld defects.

Question 11

Question: Moisture and dirt on the surface of the wire electrode is likely to cause:

a) porosity
b) cold lap
c) electrical shock
d) post-weld stress cracking

Answer 11

Answer: a) porosity.
Explanation: Contamination on the wire electrode can introduce impurities into the weld, resulting in porosity.

Question 12

Question: Excessive drag from a dirty liner is likely to cause:

a) porosity and cracking in the weld
b) slippage or bird nesting at the drive rolls
c) excessive undercut or lack of fusion
d) damage to the liner and contact tip

Answer 12

Answer: b) slippage or bird nesting at the drive rolls.
Explanation: A dirty liner increases resistance to wire movement, causing feeding issues like slippage or bird nesting.

Question 13

Question: When arc hunting occurs, the problem is likely in the:

a) wire feeder drive motor or the motor gearbox
b) wire speed control or the voltage control
c) drive rolls or the remote control switch
d) contact tip or the conduit liner

Answer 13

Answer: d) contact tip or the conduit liner.
Explanation: Arc hunting often results from issues in the contact tip or conduit liner affecting the consistency of the electrical arc.

Question 14

Question: Stubbing is caused by excessive:

a) inductance
b) voltage
c) resistance
d) wire feed speed

Answer 14

Answer: d) wire feed speed.
Explanation: High wire feed speed can lead to stubbing, where the wire pushes against the weld area without forming a proper arc.

Question 15

Question: List four causes of porosity.

Answer 15

Answer: Any four of the following are correct:

a) lack of shielding gas coverage
b) wet CO2 gas
c) excessive tip to work distance
d) excessive travel speed
e) excessive gas flow rates
f) contamination on the base material
g) excessive current or voltage
h) incorrect wire chemical analysis
i) impurities in the base metal such as sulphur or phosphorus
j) plugged gas diffuser orifices
k) loose or off-centre gas nozzle

Explanation: These factors can introduce contaminants or disrupt the welding process, leading to the formation of gas pockets within the weld.

Question 16

Question: What is the major cause of cold lap when using GMAW short-circuit metal transfer?

a) fast travel with a small bead
b) slow travel with a large bead
c) slope control set to a flat volt-amp curve
d) wire stickout too short

Answer 16

Answer: b) slow travel with a large bead.
Explanation: Slow travel speed with a large bead in GMAW short-circuit transfer can lead to insufficient penetration, resulting in cold lap.

Question 17

Question: What is the name of the condition that Figure 33 shows? List three causes of this condition.

Answer 17

Answer: The condition is whiskers. Causes include:
a) too large a root opening
b) a root face that is too thin
c) a too fast travel speed
d) excessive wire feed speed
e) improper gun manipulation
Explanation: Whiskers are a specific welding defect characterized by thin, wire-like projections from the weld, often caused by improper welding parameters or technique.

Question 18

Question: Describe the procedure for clearing a bird nest.

Answer 18

Answer: The steps include:
a) De-energize power source/feeder.
b) Cut wire at spool and tie it off.
c) Cut wire at back end of cable liner.
d) Remove contact tip; pull wire through gun and cable assembly.
e) Relieve tension on or remove idler rolls.
f) Remove bird nested wire; check for damage to drive roll assembly.
g) Manually feed wire from spool through wire feeder into back of cable liner.
h) Energize power source/wire feeder.
i) Replace drive rolls; set enough pressure to feed wire through to gun.
j) Replace contact tip; check drive roll pressure.

Explanation: Clearing a bird nest involves systematically removing and replacing components to ensure smooth wire feeding.

Question 19

Question: How often should you clean the conduit liner of a wire drive set-up?
a) once per day
b) after 20 hours of operation
c) every time the wire spool is changed
d) the liner should never need cleaning

Answer 19

Answer: c) every time the wire spool is changed.
Explanation: Regular cleaning of the conduit liner is crucial to maintain smooth wire feeding and prevent blockages.

Question 20

Question: What should you do when the liner becomes kinked?
a) Replace it.
b) Squeeze it in a vice until it straightens out and place it back into service.
c) Cut the kinked portion out, rejoin using manufacturer-approved fittings and place it back into service.
d) Stretch the liner until it straightens out and place it back into service.

Answer 20

Answer: a) Replace it.
Explanation: A kinked liner can hinder wire feed and should be replaced to ensure optimal performance.

Question 21

Question: List six things you should check for if the arc becomes unstable.

Answer 21

Answer: Any six of the following are correct:
a) worn or dirty contact tip
b) dirty liner
c) wire hang-up at spool
d) electrical stickout
e) gas supply
f) loose work lead connection
g) sharp bends in the cable assembly
h) incorrect size of liner
i) excessive drive roll pressure
j) excessive spatter build up
k) too much wire cast or helix

Explanation: These factors can affect the stability of the arc during welding, leading to quality issues in the weld.

Question 22

Question: What part of the GMAW system requires the most ongoing maintenance?
a) power source
b) regulator/flowmeter
c) wire feeder
d) gun and cable assembly

Answer 22

Answer: d) gun and cable assembly.
Explanation: The gun and cable assembly are most exposed to heat and spatter, requiring frequent maintenance.

Question 23

Question: What can result from a poor work lead connection?
a) overheating of the power source main transformer coil
b) erratic wire feed speeds
c) excessive penetration
d) an unstable arc

Answer 23

Answer: d) an unstable arc.
Explanation: A poor work lead connection can disrupt the electrical circuit, leading to an unstable arc during welding.

Question 24

Question: List four things you should check for when you see porosity in the weld when using GMAW.

Answer 24

Answer: Any four of the following are correct:
a) check for an empty cylinder
b) spatter buildup in the gas nozzle
c) obstructions in the orifices of the gas diffuser
d) kinked, disconnected, or gas line blockages
e) malfunctioning gas solenoid
Explanation: These issues can lead to inadequate gas coverage, introducing contaminants and causing porosity in the weld.

Question 25

25. What should you check for when adjusting from short-circuiting to spray transfer
    with GMAW?
    a) Ensure wire feeder drive motor is well lubricated.
    b) Make sure the power source has a high frequency current control.
    c) Make sure the gun is rated to handle higher currents.
    d) Make sure the wire electrode is at least 0.9 mm (0.035”) minimum diameter.

Answer 25

Answer: c) Make sure the gun is rated to handle higher currents.
Explanation: When shifting from short-circuiting to spray transfer, it’s crucial to ensure that the welding gun can handle the increased current levels to avoid overheating and damage.

Question 26

Question: Describe the six items you should include on an ongoing maintenance schedule and checklist for wire feed equipment.

Answer 26

Answer: The six items include:

a) Check and follow the equipment manufacturer’s recommendations.
b) Arrange with your employer to set a specified time aside for routine maintenance.
c) Check the environment around the equipment; harsh environments may require higher maintenance cycles than ideal ones.
d) Recommend additional equipment like spool covers to help keep the wire electrodes clean.
e) Put together a mini training program/checklist for the welders to use so they can maintain the equipment themselves.
f) Keep a logbook with each equipment set-up to record repairs and completed maintenance activities.
Explanation: A comprehensive maintenance schedule helps in ensuring the longevity and proper functioning of wire feed equipment.

Question 27

Question: Describe the procedure for changing a roll of wire on a GMAW system.

Answer 27

Answer: The steps include:
a) De-energize power source.
b) Remove empty roll.
c) Remove or relieve tension on idler rolls.
d) Remove contact tip; pull remaining wire through cable assembly.
e) Place new wire spool on hub; check hub brake tension.
f) Feed wire through drive roll assembly and into the liner (ensuring the wire is feeding off the roll straight into the guides).
g) Replace idler rolls; set minimum tension.
Explanation: This procedure is essential for ensuring a smooth transition and avoiding disruptions in the welding process when changing wire rolls.

Question 28

Question: How should you check for correct drive roll pressure on a GMAW set-up?

Answer 28

Answer: Drive roll pressure should be set to the manufacturer’s recommendations, and the tension should be sufficient to drive the wire without undue deformation or scarring of the wire surface.
Explanation: Proper drive roll pressure is critical for consistent wire feeding and avoiding damage to the wire.

Question 29

Question: What part of FCAW equipment requires the most ongoing maintenance?

a) the power source
b) the gas solenoid
c) the gun and cable assembly
d) the wire feeder drive motor

Answer 29

Answer: c) the gun and cable assembly.
Explanation: The gun and cable assembly in FCAW systems are prone to wear and damage due to constant exposure to heat and spatter, necessitating regular maintenance.

Question 30

Question: Name three causes of porosity with FCAW.

Answer 30

Answer: Any three of the following are correct:
a) lack of shielding gas
b) improper gun inclination
c) air drafts
d) contact tube not centred
e) dirty base material
f) excessive wire feed speed
g) moisture in the shielding gas
h) contaminated electrode

Explanation: These factors can lead to the entrapment of gases in the weld, causing porosity and compromising weld quality.