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CWI > CH. 3 SMAW Metal Joining & Cutting Processes > Flashcards

CH. 3 SMAW Metal Joining & Cutting Processes Flashcards

1
Q

Whats important about welding processes to know for the exam?

A 
Problems
Equipment
Techniques
Advantages
Limitations
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2
Q

Welding without a filler metal is

A

autogenous

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3
Q

1) What is another name for DCRP and DCEP?
2) Which does it make hotter the electrode or the work piece?
3) What kind of penetration and weld pool does DCEP have?

A

1) “DC Reverse Polarity”
2) electrode hotter
3) shallow penetrateion - wide weld

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4
Q

1) What is another name for DCSP and DCEN?
2) Which does it make hotter the electrode or the work piece?
3) What kind of penetration and weld pool does DCEN have?

A

1) “DC Straight Polarity”
2) the work piece
3) deep penetration - narrow weld

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5
Q

What is duty cycle?

A

Is the percentage of time that a power source or its accessories can be operated at rated output without overheating. The test period for arc welding is ten minutes. For example, a welding machine with a rated output of 300A at 60 percent duty cycle can deliver 300 amps of welding current for 6 minutes out of every 10 without overheating.

A. How long a welder can weld for in a given period
B. The amount of time the electrodes are being used
C. The amount of time a welding machine can be weld
D. The amount of electricity being consumed

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6
Q

SMAW electrode coating provides?

A 
Shielding from atmospher
Deoxidation to eliminate oxygen
Alloying to pull out undesirables
Ionizing to stabilize arc
Insulation (slag) to slow cool and protect
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7
Q

Which of these electrodes are not low hydrogen? SMAW

A. E7015
B. E7021
C. E7018
D. E7016

A

B. E7021

Numbers 5, 6, & 8 are low hydrogen

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8
Q

Most codes require that low hydrogen electrodes be held at a minimum oven temperature of ?

A. 150F
B. 250F
C. 350F
D. 120F

A

B. 250F

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9
Q

What do the 1, 2, and 4 mean when identifying electrodes? SMAW

E7015
E7025
E7046

A

they indicate positions

1 = any position

2 = flat or horizontal for fillet welds only

4 = downhill progression

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10
Q

What are some ways to remedy arc blow?

A
  1. change from DC to AC
  2. Hold as short an arc as possible
  3. reduce welding current
  4. angle the electrode in hte direction opposite the arc blow
  5. use heavy tack welds at either end of a joint, with intermittent tack welds along the length of the joint
  6. weld toward a heavy tack or toward a completed weld
  7. use a backstep technique
  8. weld away from hte work connection to reduce back blow; weld toward the work connection to reduce forward blow
  9. attach the work cable to both ends of the joint to be welded
  10. wrap work cable around hte work piece and pass work current through it in such a direction that the magnetic field set up will tend to neutralize the magnetic field causing the arc blow
  11. extend teh end of the joint by attaching runoff plates`
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11
Q

What are some discontinuities that can result from SMAW?

A
  1. incomplete fusion
  2. incomplete joint penetration
  3. cracking
  4. undercut
  5. overlap
  6. incorrect weld size
  7. improper weld profile
  8. others
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12
Q

What are some advantages of SMAW?

A
  1. simple equipment
  2. inexpensive
  3. welds most alloys
  4. very portable
  5. suitable for rusty, scaly materials such as ship repair or underground piping systems
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13
Q

What are some disadvantages of SMAW?

A
  1. it is very slow
  2. deposition efficiency- very low
  3. arc blow
  4. electrode storage considerations
  5. slag removal
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14
Q

What could cause porosity in a weld when SMAW?

A
  1. welder uses an arc length that is too long

2. arc blow

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15
Q

Components of typical SMAW unit include:

A
  1. Power supply & controls
  2. Power source
  3. Electrode lead
  4. Work piece lead
  5. Work piece clamp
  6. Electrode holder
  7. Electrode
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16
Q

As arc voltage drops, what happens to the arc current?

A

it rises

17
Q

What happens to the voltage and amperage if the arc length is shortened?

A

voltage decreases

amps increases

18
Q

What happens to the voltage and amperage if the arc length is increased?

A

voltage increases

amps decreases

19
Q

What is 1 technique that can be uses to remedy arc blow when SMAW?

A

backstep technique

CWI (6 decks)

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