Welding - Chapters 1-6 - First Exam
the distance the arc must jump from the end of the electrode to the plate or weld pool surface is?
Arc length
SMAW - type of current
CC - Constant current arc voltage
Type B fire extinguisher
Combustible liquids, gas, oil, paint thinner. Red square symbol
Type D fire extinguisher
Combustible metals, zinc, magnesium, and titanium. Yellow star symbol
Type A fire extinguisher
Combustible solids, paper, wood, and cloth. Green triangle symbol
Types of Welding Power
Constant Voltage CV - Rising arc voltage - RAV - Constant current - CC
DC+ vs DC-
DC+ will mean the current flows from the electrode to the base metal. This creates more heat at the electrode which creates less penetration but results in a better deposition. DC- gives you better penetration into the base metal but less filler metal is deposited.
step-down transformer
Decreases voltage and increases current. High-voltage, low amperage changes to low voltage, high amperage
Type C fire extinguisher
Electrical fires, motors, fuse boxes, welders, computers. Blue circle symbol
What is voltage?
Electrical pressure
What Is The Measurement of the electrode to the surface of the metal?
Electrode angle
Large welding lead sizes make electrode manipulation easier. T or F
False
SMAW is a rarely used welding process because of its cost and of flexibility. T or F
False
Shielded metal arc welding often continues for long periods of time. T or F
False
The temperature of a welding arc does not exceed 1,100 degrees Fahrenheit. T or F
False
FCAW
Flux-cored arc welding (FCAW)
the voltage at the electrode before striking an arc (no current being drawn)
Open-circuit voltage
OFC
Oxyfuel Gas Cutting
OFW
Oxyfuel Gas Welding, usually acytelene
ppe
Personal Protective Equipment
Parts of transformer-type welding machines
Primary coil, secondary coil, and core
If an electrode holder becomes hot, you should never dip it in water to cool it off. T or F
True
Metal as thin as 1/16 inch to several feet thick can be welded using shielded metal arc welding. T or F
True
Rectifiers must be connected to a heat sink and cool air blown over them. T or F
True
The maximum safe open circuit voltage for welders is 80 volts. T or F
True
______ controls the maximum gap the electrons can jump to form the arc.
Voltage
Three units are used to measure welding current
Voltage: electrical pressure Amperage: number of electrons flowing Wattage: power of the arc
________ is a measurement of the amount of electrical energy or power in the arc.
Wattage
SMAW - Definition
Wellding process using a flux-covered metal electrode to carry an electrical current. The current forms an arc across a gap between the work and the electrode. Molten metal travels across the gap and joins together with the base metal.
third-degree burn
a burn involving all layers of the skin; characterized by the destruction of the epidermis and dermis, with damage or destruction of subcutaneous tissue
amperage
a unit of measure of the rate of flow of electricity through a wire
The three units used to measure an electrical current are _________.
amps, watts, and volts
second degree burn
characterized by epidermal blisters, mottled appearance, and a red base? Damage extends into but not through the dermis. Recovery usually takes 2 to 3 weeks.
slag
serves as a protective coating in the stick welding process; the more or less completely fused and vitrified matter separated during the reduction of a metal from its ore.
a straight weld with little or no side-to-side motion
stringer bead
2 ways to strike an arc are
tapping and scratching
What is the Definition of welding current
the current in the welding circuit during the making of the weld.
flash burn
the damage that can be done to eyes after even brief exposure to ultraviolet light from arc welding. Flash burn requires medical attention.
Arc blow
the deflection of the arc from its normal path because of magnetic forces.
forge weld
the most ancient welding processes, is a solid-state welding process that joins two pieces of metal by heating them to a high temperature and then hammering them together
electrical resistance
the property of some materials to block the flow of electrons. Measured in ohms
________ controls the size of the arc.
Amperage
weld
"a localized coalescence (the fusion or growing together of the grain structure of the materials being welded) of metals or nonmetals produced either by heating the materials to the required welding temperatures, with or without the application of pressure, or by the application of pressure alone, and with or without the use of filler materials.".
Amperage - Welding
(A), is the measurement of the total number of electrons flowing, in the same way that gallons is a measurement of the amount of water flowing. Amperage controls the size of the arc. Amperage is associated with the welding heat.
Wattage - Welding
(W), is a measurement of the amount of electrical energy or power in the arc. Watts are calculated by multiplying voltage (V) times amperes (A),
ultraviolet
(adj) of or relating to electromagnetic radiation having wavelengths shorter than those of visible light but lover than those of x-rays
What approximately is The temperature of the arc?
11,000°F (6000°C).
Welding cables must never be spliced within ___ feet of the electrode holder
10 feet
Arc temperature range - SMAW
5500F - 36000F Averaging about 11,000F
electrical ground
A conductive connection that provides a path for electrical current to pass from an electrical component into the earth.
inverter
A device that converts DC to AC.
spot welding
A form of resistance welding where the metal components being joined are clamped between two electrodes. An electric current is passed between the electrodes causing a build up of heat at the centre of the joint, fusing the two components together.
msds
A widely used abbreviation for Material Safety Data Sheet. A MSDS contains details of the hazards associated with a chemical, and gives information on its safe use.
List welding Currents:
AC,DC-,DC+
ansi z89
ANSI rating required for hard hats to be used on the job.
AC
Alternating Current
Three different types of current used for welding are
Alternating Current: evenly distributed between (+) and (-) Direct-Current Electrode Positive: electrode positive, ground (work) negative Direct-Current Electrode Negative: electrode negative, ground (work) positive
ansi
American National Standards Institute: A private, non-profit organization that coordinates the development and use of voluntary consensus standards in the United States.
AWS stands for
American Welding Society.
Ideal process for high welding rates on thin-guage
GMAW
gmaw
Gas metal arc welding (GMAW) - commonly termed MIG (metal, inert gas), uses a wire feeding gun that feeds wire at an adjustable speed and flows an argon-based shielding gas or a mix of argon and carbon dioxide (CO2) over the weld puddle to protect it from atmospheric contamination.
gtaw
Gas tungsten arc welding... TIG..heliarc...manual welding process that uses a non-consumable tungsten electrode, an inert gas, and a separate filler material.
GFCI
Ground Fault Circuit Interrupter - Protect humans from deadly shock
What produces the heat during a shielded metal arc?
Heat is produced as electrons jump the air gap between the end of the electrodes and the work.
infrared light
Infrared light has longer wavelengths, penetrates more deeply, has less energy, and produces more than visible light; makes up 60 percent of natural sunlight.
What is wattage?
Intensity of the arc.
base metal
Material being welded
What is amperage?
Measurement of electrical current.
Constant Current is used for?
SMAW and GTAW
smaw
Shielded metal arc welding (SMAW) - also known as "stick welding", uses an electrode that has flux, the protectant for the puddle, around it. The electrode holder holds the electrode as it slowly melts away. Slag protects the weld puddle from atmospheric contamination.
Conventional Flow Theory
Starts at the positive and flows towards the negative. This is commonly illustrated in diagrams, but is not recognized as the chosen theory.
first degree burn
Superficial burns through only the epidermis.
What is welding current?
The flow of electrons.
duty cycle
The percentage of time that the welding machine will weld at its highest rated amperes.
Electron Flow Theory
Theory which states electrons flow from negative to positive
A properly sized electrode holder can overheat if its jaws are dirty or loose. T or F
True
Alternators can be smaller in size and lighter in weight than generators and still produce the same amount of power. T or F
True
Arc welding machines may be stacked to save space as long as there is enough room between them for air to circulate. T or F
True
DCEN
direct-current-electrode-negative also known as straight polarity as the direct current is used and the electrode is made negative. electrons are attracted to the positive work piece while ionized atoms in the arc column are accelerated toward the negative electrode. these processes are characterized by fast melting of the electrode. (high metal deposition rates) and shallow molten pool on the work piece. (weld penetration)
A tack weld holds pieces together until
final welding can take place.
4 welding positions are
flat, horizontal, vertical, and overhead
Dangerous fumes from welding
fumes from cadmium, lead oxide, and zinc are of particular concern to the welder
Resistance to the flow of electrons produces _____.
heat
magnetic flux lines
imaginary lines that map out the magnetic field around a magnet
elihu thomson
inventor of arc welding in 1886
Voltage - Welding
is the measurement of electrical pressure in the same way that pounds per square inch is a measurement of water pressure. Voltage controls the maximum gap the electrons can jump to form the arc. A higher voltage can jump a larger gap. Welding voltage is associated with the welding temperature.
5 basic welding joints are
lap, tee, edge, corner, butt
Advantages of SMAW
low cost, portable, and versatile
Electrons flow through a conductor from ______.
negative to positive
Operating Voltage
operating, welding, or closed circuit voltage is the voltage at the arc during welding
Duty Cycle
percentage of time a welding machine can be used continuously at maximum amperage
electrode holder
piece of equipment held by the welder that holds the electrode
Energy is lost from the weld in the form of?
radiation and convection
Operating voltage
the voltage at the arc during welding
Open Circuit Voltage
the voltage at the electrode before striking an arc
Types of light that can cause burns
ultraviolet and infrared
DCEP
when the work is made negative and the electrode is positive this is known as direct-current-electrode-positive, or reverse polarity. the positive ions impinge on the work piece, breaking up any oxide films and giving deeper penetration. however, metal deposition is lower