wire welding maintenance and troubleshooting

Question 1

Ideally, a welding power source should be located in:

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

b) an uncluttered, well-ventilated area of the shop.

Question 2

It is important to have wire guides in alignment with drive rolls on the wire drive unit. Explain your answer.
True or Flase

Answer 2

True: Misalignment can cause an unnecessary drag on the wire and lead to feeding difficulties.

Question 3

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

Answer 3

Electrical and Qualified

Question 4

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

a)vertical

Question 5

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

Answer 5

The connections are to be tight to prevent overheating of the cables and power source.

Question 6

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

b) feed freely, yet prevent a backlash of wire when feeding is stopped

Question 7

How is penetration affected when stickup is increased?

a) penetration increases
b) penetration is not affected
c) penetration is decreased
d) only penetration on groove welds is affected.

Answer 7

c) penetration is decreased

Question 8

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

a) changes the penetration of the weld

Question 9

Describe how BMAW equipment is likely to behave when the contact tip is worn out.

Answer 9

With extended use, the wire wears the contact tub orifice to an oval shape.. This causes the wire to slide easier but the transfer of current is not as efficient. arcing in the contact tube may occur, which fuses the wire ofr causes erratic wire feeding.

Question 10

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

d) inadequate gas coverage

Question 11

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

a) porosity

Question 12

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

b) slippage or bird nesting at the drive rolls

Question 13

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

d) contact tip or the conduit liner

Question 14

Stubbing is caused by excessive:

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

Answer 14

d) wire feed speed

Question 15

List four (4) causes of porosity:

Answer 15

any 4: lack of shielding gas coverage, wet CO2 gas, excessive tip to work distance, excessive travel speed, excessive gas flow rates, contamination on the base material, excessive current or voltage, incorrect wire chemical analysis, loose or off-centre gas nozzle.

Question 16

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

Answer 16

slow travel with a large bead

Question 17

free card!

Answer 17

free card!

Question 18

‘what are the 3 causes of whiskers:

Answer 18

too large a root opening, root face that is too thin, a too fast travel speed, excessive wire feed speed, improper gun manipulation

Question 19

How often should you clean the conduit liner of a wire drive set-up?

a) once per day
b) after 20 hours of operations
c) every time the wire spool is changed
d) the liner should never need cleaning

Answer 19

c) every time the wire spool is changed

Question 20

What should you do when the liner becomes kinked?

a) replace it
b) squeeze itin a vice until it straightens out and place it back into service.
c) cut the kinked portion out, rejoin using manufacturers-approved fittings and place it back into service
d) stretch the liner until it straightens out and place it back into service.

Answer 20

a) replace it

Question 21

List 6 things you should check for if the arc becomes unstable.

Answer 21

worn or dirty contact tip, dirty liner, wire hang-up at spool, electrical stickout, gas supply, loose work lead connection, sharp bends in the cable assembly, incorrect size of liner
excessive drive roll pressure, excessive spatter build up, too much wire cast or helix.

Question 22

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

d) gun and cable assembly

Question 23

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

d) an unstable arc.

Question 24

List 4 things you should check for when you see porosity in the weld when using GMAW

Answer 24

check for empty cylinder, spatter build-up in the gs nozzle, obstructions in the orifices of the gas diffuser, kinked disconnected or gas line blockages, malfunctioning gas solenoid

Question 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 current.s
d) make sure the wire electrode is at least 0.9mm minimum diameter

Answer 25

c) make sure the gun is rated to handle higher current.s

Question 26

Describe the 6 items you should include on an ongoing maintenance schedule and checklist for wire feed equipment.

Answer 26

manufacturers recommendations
arrange for routine maintenance
check the environment around the equipment
perhaps recommend additional equipment to keep electrodes clean.
training program / checklist
logbook to record repairs and maintenance.

Question 27

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

Answer 27

de-energize the power source.
remove empty roll
remove or relieve tension on idler rolls
remove contact tip, pull remaining wire through cable assembly.
place new wire spool on hub, check hub brake tension
feed wire through drive roll assembly and into the liner
replace idler rolls, set minimum tension
re-energize power source/wire feeder; feed wire to gun
replace contact tip, check and set drive roll pressure.

Question 28

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

Answer 28

drive roll pressure should be set to manufacture’s recommendation and the tension should be sufficient to drive the wire without undue deformation or scarring of the wire surface.

Question 29

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

c) the gun and cable assembly

Question 30

Name 3 causes of porosity with FCAW.

Answer 30

lack of shielding gas
improper gun inclination
air drafts
contact tube not centred
dirty base material
excessive wire feed speed
moisture in the shielding gas
contaminated electrode.