SMAW Flashcards

1
Q

Electrical Circuit

A

Path taken by electric current flowing from one terminal, through a conductor, to the other terminal

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2
Q

Current

A

Amount of electron flow through an electrical circuit, measured in amps, I x R = V

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3
Q

Conductor

A

Any material through which electricity flows easily, ex: wires, cables, busbars

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4
Q

Resistance

A

Opposition of the material in a conductor to the passage of electric current, causing the electrical energy to be transformed into heat, measured in Ohms

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5
Q

Ohm

A

Basic unit of measure for resistance, I x R = V

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6
Q

Direct Current

A

Electrical current that flows in one direction only, DCEP, DCEN

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7
Q

Alternating Current

A

Electrical current that has alternating positive and negative values, first half-cycle (positive) - current flows in one direction, second half-cycle (negative) - current flows in opposite direction

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8
Q

Frequency

A

Number of cycles (AC sine waves) per second, measured in Hertz (Hz)

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9
Q

What frequency does North America operate at?

A

60 Hz

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10
Q

What frequency does Europe operate at?

A

50 Hz

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11
Q

Polarity

A

Positive or negative state of an object, determines the direction of current flow in DC

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12
Q

DCEN

A

Electrode - negative, workpiece - positive, current flow from electrode to workpiece

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13
Q

DCEP

A

Electrode - positive, workpiece - negative, current flows from workpiece to electrode

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14
Q

Voltage

A

Amount of electrical pressure in a circuit, doesn’t flow, has most effect on height and width of weld deposit

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15
Q

Open Circuit Voltage

A

Voltage produced when welding machine is ON but no welding is being done

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16
Q

What is the open circuit voltage of constant current machines?

A

80-100V

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17
Q

Hot Start

A

Provides an extra boost of current to help establish an arc when using hard to start electrodes

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18
Q

Arc Voltage

A

Working voltage, voltage present after an arc is struck and maintained, 10-35V

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19
Q

Constant Current Welding Machine

A

Welding machine that maintains a relatively constant current over a wide range of welding voltages caused by changes in arc length, manual

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20
Q

Arc Blow

A

Deflection of the welding arc by magnetic forces that occur due to current flow, common problem in DC in corners and near joint ends, results in incomplete fusion and excessive spatter

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21
Q

What is the best way to prevent arc blow?

A

Use AC

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22
Q

Undercutting

A

Creating a groove in the base metal that is not completely filled by weld metal during the welding process

23
Q

What causes undercutting?

A

Using excessive current, traveling too fast, improper work angle

24
Q

Overlapping

A

Extending the weld metal beyond the weld toes

25
Q

When does overlapping happen?

A

When current is set too low and molten metal is deposited without actually fusing into the base metal

26
Q

Transformer

A

Electrical device that changes AC voltage from one level to another, transforms a high-voltage/low-current input into a safe and useable low-voltage/high-current output

27
Q

Rectifier

A

Electrical device that changes AC into DC

28
Q

Inverter

A

Electrical device that changes DC into AC

29
Q

What are the electrode F-groups?

A

F1: Fast-Fill, F2: Fill-Freeze, F3: Fast-Freeze, F4: Fill-Freeze

30
Q

F1: Fast-Fill Group

A

High iron powder coating with soft arc and high deposit rates, ex: E7024

31
Q

F2: Fill-Freeze Group

A

Moderately forceful arc with medium deposition rate

32
Q

F3: Fast-Freeze Group

A

Produces a crisp, deep-penetrating arc and a fast-freezing weld bead, ex: E6010

33
Q

F4: Fill-Freeze Group

A

Produces sound welds with excellent notch toughness and high ductility, ex: E7018

34
Q

What are the 5 essentials of SMAW?

A

Electrode selection, arc length, current, travel speed, electrode angle

35
Q

Electrode Selection

A

Electrode type and diameter

36
Q

Arc Length

A

Distance from the tip of the electrode to the weld pool

37
Q

What happens when arc length is too long?

A

Unstable arc, large globules, excessive spatter, incomplete fusion

38
Q

What happens when arc length is too short?

A

Fails to generate enough heat to melt base metal properly, high, uneven beads with irregular ripples, high chance of sticking

39
Q

Arc Length Size

A

Size = 1 x Diameter of Electrode

40
Q

Current Selection

A

Correct current (AC, DCEP, DCEN) for a particular electrode must be used

41
Q

What happens when amperage is too low?

A

Not enough heat to melt the base metal, weld pool is too small, poor fusion, sticking

41
Q

What happens when amperage is too high?

A

Electrode melts too fast, weld pool is large and hard to control, excessive spatter

42
Q

Travel Speed

A

Rate at which an electrode moves along a joint

43
Q

Electrode Angle

A

Combination of travel angle and work angle

44
Q

Travel Angle

A

Angle less than 90 degrees between the electrode axis and a line perpendicular to the work piece

45
Q

Push Travel Angle

A

Travel angle where the electrode points toward the direction of travel, less heat input, shallow penetration

46
Q

Drag Travel Angle

A

Travel angle where the electrode points away from the direction of travel, more heat input, deeper penetration

47
Q

Work Angle

A

Angle less than 90 degrees in a line perpendicular to workpiece and in a plane determined by the electrode axis and the weld axis

48
Q

Duty Cycle

A

Percentage of time during a specified period that a welding machine can be operated as its rated load without exceeding the temperature limits of the insulation on the component parts

49
Q

What is the time period NEMA has set the standard for a duty cycle?

A

A 10 min period

50
Q

What do the first two (and sometimes three) digits of an electrode classification number specify?

A

The minimum tensile strength of the deposited weld metal in thousands per square inch (ksi), ex: 60 ksi or 60,000 psi

51
Q

What does the third digit of an electrode classification number specify?

A

Welding position
1 - all positions
2 - flat position groove (1G), fillet welds (1F), horizontal fillet welds (2F)
4 - flat, horizontal, vertical down, overhead

52
Q

What does the last digit of an electrode classification number specify?

A

Type of coating, welding current, operating characteristics (0-8)