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welding skills processes and practices for entry level welders book 1 first edition pdf

Preface
ABOUT THE SERIES
Welding: Skills, Processes and Practices for Entry-Level Welders is an exciting new
series that has been designed specifically to support the American Welding
Society’s (AWS) SENSE EG2.0 training guidelines.

Offered in three volumes,
these books are carefully crafted learning tools consisting of theory-based texts
that are accompanied by companion lab manuals, and extensive instructor support materials.

With a logical organization that closely follows the modular structure of the AWS guidelines, the series will guide readers through the process of
acquiring and practicing welding knowledge and skills.

For schools already in
the SENSE program, for those planning to join, or for schools interested in
obtaining certifiable outcomes based on nationally recognized industry standards order to comply with the latest Carl D. Perkins Career and Technical Education in requirements, Welding: Skills, Processes and Practices for Entry-Level
Welders offers a turnkey solution of high quality teaching and learning aids.
Career and technical education instructors at the high school level are often
called upon to be multi-disciplinary educators, teaching welding as only one of
as many as five technical disciplines in any given semester.

The Welding: Skills,
Processes and Practices for Entry-Level Welders package provides these educators
with a process-based, structured approach and the tools they need to be prepared to deliver high level training on processes and materials with which they
may have limited familiarity or experience.

Student learning, satisfaction and
retention are the target of the logically planned practices, supplements and full
color textbook illustrations.

While the AWS standards for entry level welders are
covered, students are also introduced to the latest in high technology welding
equipment such as pulsed gas metal arc welding (GMAW-P).

Career pathways
and career clusters may be enhanced by the relevant mathematics applied to
real world activities as well as oral and written communication skills linked to
student interaction and reporting.

INTRODUCTION
As methods of joining materials improved through the ages, so did the environment and mode of living for humans.

Materials, tools, and machinery improved as civilization developed.
Fastening together the parts of work implements began when an individual
attached a stick to a stone to make a spear or axe.

Egyptians used stones to
create temples and pyramids that were fastened together with a gypsum mortar.

Some walls that still exist depict a space-oriented figure that was as appropriate then as now—an ibis-headed god named Thoth who protected the
moon and was believed to cruise space in a vessel.
Other types of adhesives were used to join wood and stone in ancient
times.

However, it was a long time before the ancients discovered a method
for joining metals.

Workers in the Bronze and Iron Ages began to solve the
problems of forming, casting, and alloying metals.

Welding metal surfaces
was a problem that long puzzled metalworkers of that period.

Early metaljoining methods included forming a sand mold on top of a piece of metal
and casting the desired shape directly on the base metal, so that the two
parts fused together form a single piece of metal, Figure 1.1. Another early
metal-joining method was to place two pieces of metal close together 

WELDING DEFINED
A weld is defined by the American Welding Society (AWS) as “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.” Welding is defined as “a
joining process that produces coalescence of materials by heating them
to the welding temperature, with or without the application of pressure
or by the application of pressure alone, and with or without the use of
filler metal.” In less technical language, a weld is made when separate
pieces of material are joined to form one piece by heating them to a temperature high enough to cause softening or melting and flow together.
Pressure may or may not be used to force the pieces together.

In some
cases, pressure alone may be sufficient to force the separate pieces of
material to combine and form one piece.

Filler material is added when
needed to form a completed weld in the joint.

It is important to note
that the word material is used because today welds can be made from a
growing list of materials, including plastic, glass, and ceramics

USES OF WELDING
Modern welding techniques are employed in the construction of numerous products. Ships, buildings, bridges, and recreational rides are fabricated using welding processes, Figures 1.3 and 1.4.

Welding is often used
to produce the machines that are used to manufacture new products.
Welding has made it possible for airplane manufacturers to meet the
design demands of strength-to-weight ratios for both commercial and
military aircraft.

WELDING PROCESSES
The number of different welding processes has grown in recent years.
These processes differ greatly in the manner in which heat, pressure, or
both, are applied and in the type of equipment used

OCCUPATIONAL OPPORTUNITIES IN WELDING
The American welding industry has contributed to the widespread
growth of welding and allied processes.

Without welding, many of the
products we use on a daily basis could not be manufactured.

The list of
these products grows every day, thus increasing the number of jobs for
people with welding skills.

These well-paying jobs are not concentrated
in major metropolitan areas but are found throughout the country and
the world.

Because of the diverse nature of the welding industry, the
exact job duties of each skill area will vary.

The following are general
descriptions of the job classifications used in our profession; specific
tasks may vary from one location to another.
• Welders perform manual or semiautomatic welding.

They are the
skilled craftspeople who, through their own labor, produce the
welds on a variety of complex products, Figure 1.11.
• Tack welders perform manual or semiautomatic welding to
produce tacks, which often help the welder by making small welds
to hold parts in place.

The tack weld must be correctly applied so
that it is strong enough to hold the assembly but does not interfere
with the finished welding.
• Welding operators run adaptive control, automatic, mechanized, or
robotic welding equipment.
• Welders’ helpers are employed in some welding shops to clean
slag from the welds and help move and position weldments for the
welder.
• Welder assemblers, or welder fitters, position all the parts in their
proper places and make ready for the tack welders.

These skilled
workers must be able to interpret blueprints and welding

TRAINING FOR WELDING OCCUPATIONS
Generally, several months of training are required to learn the basics of a
welding process. To become a skilled welder, both welding school and
on-the-job experience are required.

Because of the diverse nature of the
welding industry, no single list of skills can be given that meets every
job’s requirement. However, there are specific skills that are required of
most entry-level welders.

The American Welding Society, in partnership
with the U.S. Department of Education, conducted a survey of the welding industry to define guidelines for knowledge and skills required in the
welding workplace. In 1995, the AWS published a guideline curriculum
for entry-level welders.

The program is called SENSE, which stands for
Students Excelling through National Standards in Education. This book
covers those skill requirements.

QUALIFIED AND CERTIFIED WELDERS
Welder qualification and welder certification are often misunderstood.
Being certified does not mean that a welder can weld anything, nor
does it mean that every weld the welder makes is acceptable.

It means
that the welder has demonstrated the skills and knowledge necessary to
make good welds in a particular process, on a specified alloy, in one or
more positions.

To ensure that a welder is consistently making welds that
meet the standard, welds are inspected and tested.

The more critical the
welding, the more critical the inspection and the more extensive the testing of the welds.

AWS ENTRY-LEVEL WELDER QUALIFICATION AND WELDER
CERTIFICATION
The AWS entry-level welder qualification and certification program specifies a number of requirements not normally found in the traditional
welder qualification and certification process. The additions to the AWS
program have broadened the scope of the test.

Areas such as practical
knowledge have long been an assumed part of most certification programs but have not been a formal part of the testing process. Most companies have assumed that welders who could produce code-quality welds
could understand enough of the technical aspects of welding.
Today, however, greater importance is placed on the technical knowledge of the process, code, and other aspects of the complete welding
process. This change is due to the greater complexity of many welding
processes and an increased responsibility of companies and their welders
to ensure the quality and reliability of weldments.

It is important not only
that the weld be correctly performed but also that the welder know why it
must be performed in such a specific manner. This is all intended to
increase accuracy and reduce rejection of welds.
A written test must be passed with a minimum grade of 75% on all
areas except safety.

The safety questions must be answered with a minimum accuracy of 90%. The following subject areas, covered in this textbook series, are included in the test:
• welding and cutting theory
• welding and cutting inspection and testing
• welding and cutting terms and definitions (Glossary)
• base and filler metal identification

EXPERIMENTS AND PRACTICES
This textbook series contains experiments and practices. These are
intended to help you develop your welding knowledge and skills.
The experiments are designed to allow you to see what effect changes
in the process settings, operation, or techniques have on the type of weld
produced.

When you do an experiment, you should observe and possibly
take notes on how the change affected the weld.

Often as you make a
weld it will be necessary for you to make changes in your equipment settings or your technique to ensure that you are making an acceptable
weld.

By watching what happens when you make the changes in the
welding shop, you will be better prepared to decide on changes required
to make good welds on the job.

METRIC UNITS
Both standard and metric (SI) units are given in this text. The SI units are
in parentheses ( ) following the standard unit.

When nonspecific values
are used—for example, “set the gauge at 2 psig,” where 2 is an approximate value—the SI units have been rounded off to the nearest whole
number.

Rounding-off is used in these cases to agree with the standard
value and because whole numbers are easier to work with. SI units are
not rounded off only when the standard unit is an exact measurement.
Often students have difficulty understanding metric units because
exact conversions are used even when the standard measurement is an
approximation.

Rounding off the metric units makes understanding the
metric system much easier, Table 1.6.

By using this approximation
method, you can make most standard-to-metric conversions in your
head without needing to use a calculator.