120103d Flashcards by Megan Read

When adjusting wire tension on the drive rolls (drive roll tension) at what point do you have enough pressure? explain

once you have a positive continuous feed without deforming or scarring the surface of the wire.

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In what direction do you blow out the liner when changing a spool of wire?
a) in the direction of wire travel
(machine to gun)
b) in reverse direction of wire travel
( gun to machine)

b) in reverse direction of wire travel
( gun to machine)

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What does arc hunting mean?

chips have built up in the liner
- happens often on flexible steel coil liners

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If blowing out a liner does not fix the arc hunting problem what should you do?

soak the liner in solvent that leaves no residue then blow it out with clean compressed air
or replace liner

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For fillet welds what is the correct electrode angle in relation to the joint?
a) 1/4 the angle
b) 1/2 the angle
c) 3/4 the angle

b) 1/2 the angle = 90 degrees

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Explain the 2 following terms
Forehand
Backhand

Forehand points the electrode in the direction of travel

Backhand points the gun at the back of the puddle

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When you change electrode inclination what weld characteristics are changed?

weld profile and depth of penetration

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When using forehand is the bead shape
a) flatter & less penetration
b) convex & less penetration
c) concave & more penetration
d) concave and less penetration

a) flatter & less penetration

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When using back hand is the bead shape
a) flatter & less penetration
b) convex & less penetration
c) concave & more penetration
d) concave and less penetration

c) concave & more penetration
- narrower bead with a higher crown

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When using no inclination is the bead shape
a) flatter & less penetration
b) convex & less penetration
c) concave & more penetration
d) concave and less penetration

d) concave and less penetration

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At what backhand inclination range do you obtain max penetration?
a) 5-10 degrees
b) 15-20 degrees
c) 18- 25 degrees
d) 20-25 degrees

b) 15-20 degrees

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What electrode extension length is recommended using GMAW short circuiting?
a) 1/4”
b) 3/16”
c) 3/8”
d) 1/2”

c) 3/8”

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What problems can be caused by slow travel speeds using GMAW & short circuiting metal transfer

Large weld beads and possible overlaps with lack of fusion

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When travel speed is increased using GMAW & short circuiting metal transfer what problem may occur?

possible undercut at the toes of the weld

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What happens to your arc in GMAW if the ground connection is inadequate?

an unstable arc

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Explain stubbing

when the electrode (wire) comes in contact with the base metal but fails to start an arc immediately.

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What is generally the cause of stubbing?

excessive wire feed speed, low arc voltage or heavily scaled base metal
or with GMAW excessive slope settings

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Explain Arc Hunting

when the wire feed becomes erratic and an unstable arc develops

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What is generally the cause of arc hunting?

from severe drag in the conduit liner or contact tip
- causes unstable rate of wire feed speed, and some cases wire pile up

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What is the main thing to ensure to prevent arc hunting?

ensure the wire guides and drive rolls are properly aligned

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What causes porosity?

A reaction with atmosphere, moisture or other contaminations

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Match the porosity causes to the remedies
Causes
C1. Lack of gas coverage due to drafts, the nozzle is clogged with spatter or loss of gas flow
C2. Excessive Tip to work Distance
C3. Excessive gas flow
C4. Foreign material on surface of filler and base metal
C5. Excessive current or voltage

Remedies
R1. Move Gun closer to work to reduce electrode stick out and nozzle to work distance
R2. Check for shielding gas flow. If needed in crease the flow using a wind break or remove spatter build up from the nozzle.
R3. Reduce gas flow
R4. Use settings recommended for filler metal used
R5. Clean and protect wire from dirt and remove rust, oil and other contaminants from the weld joint.

C1 - R2
C2 - R1
C3 - R3
C4 - R5
C5 - R4

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Match the Undercut causes to the remedies
Causes
C1. Incorrect electrode angle
C2. Travel Speed to fast
C3. Insufficient pause time on the edges of weave beads
Remedies
R1. Increase side wall pause time
R2. Point towards the undercut
R3. Slow down to allow puddle to blend with base metal

C1 - R2
C2 - R3
C3 - R1

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What is a weld failure that is of concern using GMAW. What testing method is it difficult to detect with

Lack of fusion & it is hard to detect using x-ray

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What is the only weld test method that is accurate for GMAW processes? a) Radiographic b) magnetic c) bend test d) ultrasonic

c) bend test

What is the major cause of cold lap (lack of fusion) using GMAW?

carrying a large bead with slow travel speeds. sometimes referred to as pillowing effect ( little to no penetration of the base metal as the bead absorbs the force and heat of the arc without transfering it to the base metal)

Match the Causes of lack of fusion with the Remedies Causes C1 - Improper manipulation of electrode holder C2 - Puddle to large C3 - Welding current is to low Remedies R1 - Reduce wire feed and move wire from the centre of the puddle to the leading edge to increase travel speed R2 - Increase current settings or reduce electrode stick out R3 - Work wire into the side wall or leading edge of puddle - do not allow the puddle to do the fusing

C1 - R3 C2 - R1 C3 - R2

What does WFS stand for

Wire feed speed

Is the following statement correct? Y/N WFS = Amperage = Penetration

Yes

Match the Causes of lack of fusion with the Remedies Causes C1 - Current is set to high C2 - Excessive root opening or root face is to small C3 - Travel Speed is to slow Remedies R1 - Increase travel speed to reduce heat output R2 - Increase wire stick out and weave to control puddle action R3 - Reduce wire feed speed (WFS)

C1 - R3 - Reduce wire feed speed (WFS) C2 - R2 - Increase wire stick out and weave to control puddle action C3 - R1 - Increase travel speed to reduce heat output

Match the Causes of lack of penetration with the Remedies Causes C1 - Root opening to narrow or root face to large C2 - Stick out to long Remedies R1 - Increase root opening : increase welding current and reduce electrode stick out. Reduce root face width R2 - Reduce electrode stick out

C1- R2 C2- R1

What is another name for slag inclusions?

Wagon tracks depending on location and shape

What are 4 causes of slag inclusions

Any of the following 6 are correct however 1-4 are most important 1. Improper electrode manipulation 2. Inadequate pre-weld cleaning 3. Inadequate interpass cleaning 4. Current setting to low 5. Preceding pass to convex 6. To much voltage on succeeding passes

What is considered to be the most serious of all weld failures? a) Inclusions b) Porosity c) Under cut d) Cracking

d) Cracking

What is the cause of cracking if the remedy is as follows; Redesign joint; use preheat and post heat; use weave beads to increase heat input a) Faulty design b) Improper technique c) To small weld bead d) Rigidity of joint

d) Rigidity of joint

List 5 causes of Porosity within the weld bead if the problem is in the process

- Lack of shielding gas - Improper inclination - Air drafts - Contact tube not centred - Dirty base material

List 2 Causes of Stubbing if the problem is in the process

- Excessive wire speed - Arc voltage to low

List 2 Causes of Burnback if the problem is in the process

- Wire speed to slow - Voltage is to high

List 3 Causes of Unstable Arc if the problem is electrical

- loose cable connections - badly worn or dirty contact tip - loose work lead connection ( ground)

List the main cause of Arc Hunting & Burn backs if the problem is electrical

- Incorrect polarity

What are the 5 causes of wire hang up if the problem is mechanical

- Excessive drive roll pressure - incorrect conduit liner or contact tip - misaligned drive rolls or wire guides - misaligned drive rolls or wire guides - restriction within gun & cables - conduit liner dirty, worn, or to long

What are the 4 main causes of hunting & burn backs if the problem is mechanical

- insufficient drive roll pressure - dirty or worn contact tube kinked wire or coiled gun cable - conduit liner dirty, worn or to long

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 of the shop d) an unventilated and specially enclosed mezzanine area

b) an uncluttered well ventilated area of the shop

It is important to have wire guides in alignment with drive rolls on the wire drive unit T/F & explain

True misalignment can cause unnecessary drag and cause feeding difficulties

The installation of a power source must be done in accordance with local _______ codes and completed by _________ personnel.

electrical codes qualified personnel

To obtain an accurate reading from a flow meter it must be mounted in what position

Vertical

Why must you insure that all electrical fittings on the welding leads have a tight connection.

to prevent overheating of cables and power source

The wire spool hub should be adjusted in order to a) prevent unwinding go the wire spool b) feed freely, yet prevent 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

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

How is penetration affected when the stockout is increased

penetration decreases

Changing the 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

a) changes the penetration of the weld

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

- Erratic feeding - Orifice becomes oval causing the transfer of the current to be inefficient - Arcing in the tip may occur

Excessive spatter build up in the nozzle can cause a) undercut at the weld edges b) excessive metal flow c) and increase in stick out d) inadequate gas coverage

d) inadequate gas coverage

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

a) porosity

Excessive drag from a dirty liner is likely to cause a) porosity and cracking in the weld b) slippage or bird nesting in the drive rolls c) excessive undercut or lack of fusion d) damage to the liner and contact tip

b) slippage or bird nesting in the drive rolls

When arc hunting occurs the problem is likely in the a) wire feeder drive motor or the motor gear box b) wire speed control or the voltage control c) drive rolls or the remote control switch d) contact tip or the conduit liner

d) contact tip or the conduit liner

Stubbing is caused by excessive a) inductance b) voltage c) resistance d) wire feed speed (wfs)

d) wire feed speed (wfs)

List 4 causes of porosity

Lack of shielding gas contamination of base metal excessive current or voltage excessive tip to work distance

What is the major cause of cold lap when using GMAW short circuit metal transfer a) fast travel with small bead b) slow travel with large bead c) slope control set to flat volt-amp curve d) wire stick out is too short

b) slow travel with large bead

What are 3 causes of whiskers

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

List the 10 steps in clearing a bird nest

1. Shut down the machine and unplug 2. Cut the wire at the spool and tie it off to prevent unraveling 3. Cut wire at the back of the cable liner 4. Remove contact tip & pull wire through 5. relieve tension on or remove idler rolls 6. remove the birdnested wire & check drive roll assembly for damage 7. Manually feed wire from the spool through the wire feeder into the back of cable liner 8. energize power source/wire feeder 9. Replace drive rolls & set pressure 10. replace contact tip and check drive roll pressure

How often should you clean the conduit liner of a wire drive setup a) once a day b) after 20 hours of use c) every time the wire spool is changed d) the liner should never need cleaning

c) every time the wire spool is changed

What should you do if the liner becomes kinked?

replace it

List 6 things you should check if the arc becomes unstable

All are correct but the top 6 are most important - worn or dirty contact tip - excessive spatter build up - electrical stick out - gas supply - loose work lead connections - sharp bends in the cable assembly - wire hanging up at spool - incorrect size of liner - excessive drive roll pressure - dirty liner - to much wire helix or cast

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

d) gun and cable assembly

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

a) overheating of the power source main transformer coil

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

Any of these are correct - check for an empty cylinder - spatter build up on nozzle - obstructions in orfices - kinked or disconnected gas line blockages - malfunctioning gas solenoid

How should you check for correct drive roll pressure on a GMAW setup?

set to manufacturer recommendations. the tension should be sufficient to push the wire without undue deformation or scarring of the wire yet slip if there is an issue

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

c) the gun and cable assembly

What is the included angle of a fillet weld a) 10° b) 40° c) 70° d) 90

d) 90°

What is another term for stickout?

Electrode extension

What is the proper electrode extension for GMAW using short circuiting transfer? a) 1/2" b) 1/4" c) 3/8" d) 3/4"

c) 3/8"

Match the porosity causes with their remedies 1. Lack of gas coverage due to drafts, the nozzle clogged with spatter or loss of gas flow 2. 2. Excessive tip to work distance 3. Excessive gas flow 4. Foreign material on surface of filler and base metal 5. Excessive current or voltage a) Reduce gas flow b) Use settings reccommend for filler metal used c) Move gun closer ro work to reduce electrode stickout and nozzle to work distance d) Check for shielding gas flow. If needed increase gas flow using a wind break or remove spatter build up from nozzle. e). Clean and protect wire from dirt and remove rust, oil and other contamininants from the weld joint

1 - D 2 - C 3 - A 4 - E 5 - B

Explain the following terms Stubbing Burn Backs Arc hunting

Trouble shooting equipment. Problems may be placed into one of 3 categories. a) processes, electrical mechanical b) unstable, stable, fused c) stubbing, burn backs, arc hunting d) Guide, conduit, liner

a) processes, electrical, mechanical

What are the 3 causes of undercut?

Incorrect electrode angle Travel speed to fast Insufficient pause time on the edges of the weave beads

What weld test works on GMAW

bend test

Explain the term pillowing

The wire rides on top of the puddle and shorts out on the surface of it. The puddle absorbs the force and heat of the arc and it doesnt transfer to the base metal.

What are 3 causes of lack of fustion?

Impropper manipulation of gun Puddle to large welding current to low

Is the following statement true? WFS= Amperage=Penetration

Yes it is correct

Match the 3 burn through causes with their remedies 1. Current set to high 2. Excessive root opening 3. travel speed to slow a) Increase travel speed to reduce heat input b) Reduce wire feed speed c) Increase stickout and weave to control puddle action

1 - B 2 - C 3 - A

What is another name for slag inclusions depending on their location?

Wagon Tracks

What are 4 causes of slag inclusions

Impropper electrode Inadequate pre weld cleaning Inadequate interpass cleaning Current setting to low

What is the most serious weld defect and why

Cracking - it often leads to complete failure of the weld

If the regidity of a joint is a cause of cracking what is the remedy? a) use preheat and follow with stress relieving procedures b) redesign joint, use preheat and post heat; use weave beads to increase heat input c) Use back stepping sequence to slow the cooling d) Preheat to slow the cooling rate

b) redesign joint, use preheat and post heat; use weave beads to increase heat input

What are 5 causes of porosity in the weld bead?

Lack of shielding gas Improper gun inclination Air drafts contact tube not centred Dirty base material

What are 2 causes of stubbing?

Excessive wire speed arc voltage to low

What are the 3 causes of burnbacks?

Wire speed to slow voltage to high incorrect polarity

What are 3 causes of unstable arc

loose cable connections badly worn or dirty contact tip loose work lead connections

What are 3 mechanical problems causing wire hangups

All below are correct - Excessive drive roll pressure - incorrect conduit liner or contact tip - misaligned drive rolls or wire guides - restriction within gun and cables - conduit liner dirty, worn or to long

What are 3 mechanical problems that cause hunting and burnbacks

-Dirty or worn contact tube - Insufficient drive roll pressure - kinked wire or coiled gun cable - conduit liner dirty, worn or to long

Porosity in GMAW may be caused by: a) pure argon b) a loose ground clamp c) contaminants on the wire d) a worn conduit liner

c) contaminants on the wire

Which of the following is caused from a poor work lead connection a) overheated transformer coils in the power source b) decreased wire speed c) excessive penetration d) an unstable arc

d) an unstable arc

What could be the cause of non- metallic elements ( inclusions) trapped in the weld a) improper electrode manipulation b) inadequate interpass cleaning c) current adjustment to low d) all of the above

d) all of the above

Weld bead cracking could be the result of: a) short stick out b) using C25 c) an overheated welding gun d) rigidly fixed joints

d) rigidly fixed joints

The contact tube should be recessed in the nozzle to a max 1/4" for which type of metal transfer? a) short circuit b) globular c) spray d) all of the above

c) spray

Bird nesting in the wire feeder could be caused by? a) the feed cable being to large for the wire b) the conduit liner is misaligned with drive rolls c) excessive pressure on wire spool break drive roll settings is to loose

b) the conduit liner is misaligned with drive rolls

Which of the following techniques would most likely cause cold lap on a 2F lap weld

a) wire added to the leading edge of the puddle b) travel speed to slow c) excessive current settings d) travel speed to fast

Which of the following testing procedures is excluded from the CSA code as a method for testing GMAW welds done with short circuit metal transfer? a) bend testing b) radiographic testing c) dye penetrant testing d) magnetic particle testing

b) radiographic testing

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120103d Flashcards

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