WELDING AND METAL FABRICATION PDF

 

Preface

For many welding jobs it can be as important to be able to lay out and fit up the
weldment as it is to be able to weld it.

This textbook, therefore, combines the
skills of measuring, cutting, shaping, fitting, welding, and finishing.
The cover photo of Welding and Metal Fabrication was taken of me in my
hangar as I was making a GTA weld on tubing.

Aircraft tubing is used to make a
number of parts for an aircraft, including the engine mount.

Today, many lightsport aircraft, like this KitFox, can be built and flown by individuals.
All of the welding equipment required to build a homebuilt light-sport aircraft is shown in the cover photo.

With some hand tools, a few power tools, and
the welding and fabrication skills taught in this book, you too could build your
own aircraft.

There is nothing like the feeling of freedom one experiences as the
pilot of your own plane.
Whether you build your own aircraft or you build anything else, there is a
sense of accomplishment and a great feeling of pride in being able to point at
something and say, “I made that.”

Over 30 years ago, I owned a welding company
that made agricultural equipment, and I still look at farm equipment as I drive
through the countryside to see if one of my units is out there in the field. Recently,
my niece was in a volleyball playoff.

It was being held in an empty warehouse that
had been converted into a gym.

I proudly told my wife, “I made the ramp for cars
and light trucks at the loading dock on this building.”

I had made it over 20 years
ago, and it was still there and being used to drive into the warehouse.
Not only have I fitted and welded things on my jobs, I have made parts for
airplanes, barbeque grills, step and tow truck bumpers, truck racks, farm gates,
wood stoves, compost bins, car jack stands, bases for power tools, toys, furniture, tools, car trailers, boat trailers, utility trailers, and hundreds of other big
and small welded fabrications.
Welding and Metal Fabrication is designed to help you develop all of the
skills to become a highly paid versatile welder.

In addition, it is designed to
make the process of learning to weld interesting and rewarding by having everything you weld on become something you can take home and use.

The projects
within each of the fabrication and welding chapters are designed to be functional even though the welds may be your first attempts at welding.

So at first
do not be overly critical of your welding skills, they will improve as you advance
through the textbook.

In that way, both your fabrication skills and your welding
skills will improve together.
This textbook is the result of my more than 45 years of welding and fabrication experience. In addition to my personal experiences, I have drawn valuable welding and fitting information from many friends, colleagues, and former
students.

I know that not everyone who learns welding and fitting will use it to
earn their primary paycheck; for some it will be a hobby or part-time job.

CHAPTER 1

A welded metal fabrication is primarily assembled
using one or more of the following processes: welding, thermal cutting, or brazing.
• A weldment is an assembly in which its component
parts are all joined by welding.
In some cases, a welded fabricated part may
require some postweld finishing such as grinding,
drilling, machining, or painting to complete the
fabrication.

Welding Applications
Modern welding techniques are employed in the construction of numerous products.

Ships, buildings,
bridges, and recreational rides are examples of welded
fabrications, Figure 1-3.
The exploration of space would not be possible
without modern welding techniques.

From the very
beginning of early rockets to today’s aerospace industry, welding has played an important role.

Many of aerospace welding advancements have helped
improve our daily lives.
Many experiments aboard the Space Station
have involved welding and metal joining.

The International Space Station was constructed using many
advanced welding techniques.

Someday, welders will
be required to build even larger structures in the
vacuum of space

Welding is used extensively in the manufacture
of automobiles, farm equipment, home appliances,
computer components, mining equipment, and construction equipment.

Railway equipment, furnaces,
boilers, air-conditioning units, and hundreds of other

metal that could be heated in a forge and hammered
together, Figure 1-1. At the dawn of the Iron Age, rivets were used to fabricate large metal structures like
bridges, boilers, trains, and ships, Figure 1-2. But with
the advent of modern welding, cutting, and brazing,
civilization began advancing more rapidly.

In fact,
modern civilization could not exist without welding.
Today, everything we touch was manufactured using
some welding process or was made on equipment
that was welded.

Fabrication Steps
The process of metal fabrication can be divided into
several, often distinct steps.

Following are the primary
steps for fabrication:
• Layout—the process of drawing lines on the raw
metal stock according to the parts drawings and
specifications, Figure 1-4.
• Cut out—the process of removing all of the unwanted
material around the laid-out part or sometimes just
cutting material to the desired length.

Some of the

WELDING DEFINED
Most people think of welding as either a gas torch or
electric arc welding process.

They also think of it as
just melting metal together.

In the earlier history of
welding, that was true, but welding is a lot more than
that today. For example, welds can be made without
an arc or flame with the induction welding (IW) process; without heat using the pressure welding (PW)
process; or with an explosive using the explosion welding (EW) process.

In fact, welding today is much more
than the basics; it can be a very sophisticated process.
The American Welding Society’s (AWS) definition of welding is very technical to reflect the differences in the welding processes used today.

The AWS
definition of welding states that welding is “a localized
coalescence 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.”

The term coalescence
means the fusion or growing together of the grain
structure of the materials being welded.

The definition includes the terms metals or nonmetals because
materials such as plastics ceramics, and so forth, are
not metals and they can be welded.

The phrase with
or without the application of pressure is important
because without the application of significant pressure, some of the processes would not work, such as
electric resistance welding (ERW) and friction welding
(FW).

In some welding processes only pressure is used
to cause localized coalescence such as the PW and EW
processes.

And the last part of the definition says with
or without the use of filler materials, meaning welded
joints can be made by using only the base material.
A nontechnical definition of welding would be
that welding is the joining together of the surface(s)
of a material by the application of heat only, pressure
only, or with heat and pressure together so that the
surfaces fuse together.

A filler material may or may
not be added to the joint.

Weld Quality
We would like to think that every weld is made perfectly, with not even a slight flaw or imperfection

WELDING AND CUTTING
PROCESSES
Welding processes differ greatly in the manner in
which heat, pressure, or both heat and pressure are
applied and in the type of equipment used. Table 1-1
lists various welding and allied processes.

Some 67
welding processes are listed, requiring hammering,
pressing, or rolling to effect the coalescence in the
weld joint.

Other methods bring the metal to a fluid
state, and the edges flow together.

Gas Metal Arc Welding
Gas metal arc welding (GMAW) uses a solid electrode
wire that is continuously fed from a spool, through the
welding cable assembly, and out through the gun.

A shielding gas flows through a separate tube in the cable
assembly, out of the welding gun nozzle, and around
the electrode wire.

The welding power flows through
a cable in the cable assembly and is transferred to the
electrode wire at the welding gun.

The GMA weld is
produced as the arc melts the end of the continuously
fed filler electrode wire and the surface of the base
metal.

The molten electrode metal transfers across the
arc and becomes part of the weld.

The gas shield flows
out of the welding gun nozzle to protect the molten
weld from atmospheric contamination.

Assembling the Parts
The assembly process for a weldment can be as simple as holding a part in place with one hand as you
make a tack weld using your other hand.

But most
of the time, it is much more complicated, requiring
clamps, jigs, or fixtures to hold the parts in place for
tack welding or finish welding, Figure 1-19. A variety
of hand tools such as squares, magnetic angle blocks,
clamps, and locking pliers are commonly used to align
and hold the parts for welding.

CHAPTER 2

Welding fabrication is a very large and diverse
industry.

This chapter concentrates on only that portion
of welding fabrication safety related to the areas of
light metal.

You must read, learn, and follow all safety
rules, regulations, and procedures for those areas.
Light welding fabrication, like all other areas of
welding work, has a number of potential safety hazards.

These hazards need not result in anyone being
injured.

Learning to work safely is as important as
learning to be a skilled welding fabrication worker.
You must approach new jobs with your safety in
mind.

Your safety is your own responsibility, and you
must shoulder that responsibility.

It is not possible to
anticipate all of the possible dangers in every job. This
text may not cover some dangers.

You can get specific
safety information from welding equipment manufacturers and their local suppliers, your local college and
university, and the World Wide Web

BURNS
Burns are one of the most common and painful injuries
that occur in welding fabrication.

Burns can be caused
by ultraviolet light rays as well as by contact with hot
welding material.

The chance of infection is high with
burns because of the dead tissue that results.

It is important that all burns receive proper medical treatment
to reduce the chance of infection.

Burns are divided
into three classifications, depending upon the degree of
severity.

The three classifications include first-degree,
second-degree, and third-degree burns.

Burns Caused by Light
Some types of light can cause burns.

There are three
types of light—ultraviolet, infrared, and visible.

Ultraviolet and infrared are not visible to the unaided
human eye but can cause burns.

During welding, one
or more of the three types of light may be present.
Arc welding and arc cutting produce all three kinds
of light, but gas welding produces only the less hazardous visible and infrared lights.

Third-Degree Burns
Third-degree burns have occurred when the surface
of the skin and possibly the tissue below the skin
appear white or charred.

There may be cracks or
breaks in the skin, Figure 2-3. Initially, little pain
is present because the nerve endings have been
destroyed.

Do not remove any clothes that are stuck
to the burn.

Do not put ice water or ice on the
burns; this could intensify the shock reaction. Do
not apply ointments, sprays, antiseptics, or home
remedies.

If the victim is on fire, smother the flames
with a blanket, rug, or jacket.

Breathing difficulties
are common with burns around the face, neck, and
mouth; be sure that the victim is breathing. Place a
cold cloth or cool water on burns of the face, hands,
or feet to cool the burned areas.

Cover the burned
area with thick, sterile, nonfluffy dressings. Call for
an ambulance immediately if needed; people with
even small third-degree burns need to consult a
doctor.

CHAPTER 3

TYPES OF NUMBERS
Welding fabricators use only a few types of numbers
on a regular basis. They most commonly use the following types of numbers:

EQUATIONS
AND FORMULAS
An equation is a mathematical statement in which
both sides are equal to each other; for example, 2X = 1Y.
In this equation, the value of X is always going to be
1/2 of the value of Y.

An example of an equation used
in metal fabrication would be: the number of hours
worked (hrs) ´ pay per hour ($) = total labor bill (T),
or hrs ´ $ = T. If either the hours or the pay rate goes
up, the total bill goes up too and vice versa.

Multiply and Divide
Mixed Numbers
The easiest way to multiply and divide mixed numbers is to convert the large units to the smallest units.
Multiply or divide the small units as if they were
whole numbers.

Then convert the answer back to a
mixed number.

You might need to multiply mixed
numbers to find the area of a piece of metal or to find
out how much material you need to cover the floor of
a trailer.

Find the area of a small lawn tractor bed that
is 4 ft long and 3 ft 6 in. wide.