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