Farm Mechanic: Performing welding, riveting and soldering

The combination welding and cutting torch offers more flexibility because a cutting head,
welding tip, or heating tip can be attached quickly to the same torch body. Combination
torch sets are often used in schools, automotive repair shops, small welding shops, or in
any other situation where flexibility is needed. The combination torch sets usually are more
practical for portable welding, since the single unit can be used for both cutting and
welding.

Q5. What is a reverse flow valve and what is its main purpose?

Answer:

The purpose of the reverse flow valve is to prevent gases from accidentally flowing through
the torch and into the wrong hose. If the gases being used are allowed to mix in the hose
or regulator, they might explode. The reverse flow valve is a spring-loaded check valve
that closes when gas pressure from a backflow tries to occur through the torch valves.
Some torches have reverse flow valves built into the torch body, but most torches must
have these safety devices added. If the torch does not come with a reverse flow valve, one
must be added to either the torch end or regulator end of the hose.

Q6. Describe backfires and flashbacks and how they occur.

Answer:

• A backfire occurs when a flame goes out with a loud snap or pop. A backfire may be
caused by:
— Touching the tip against the workpiece;
— Overheating the tip;
— Operating the torch when the flame settings are too low;
— A loose tip;
— Damaged tips; or
— Dirt present in the tips.

The problem that caused the backfire must be corrected before relighting the torch.
A backfire may cause a flashback.
A flashback occurs when the flame burns back inside the tip, torch, hose, or
regulator. If the torch does flashback, close the oxygen valve at once and then close
the fuel valve. The order in which the valves are closed is not as important as the
speed at which they are closed. A flashback that reaches the cylinder may cause a
fire or an explosion.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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7. What are some factors that affect the weld?

Answer:

• Factors Affecting the Weld. Several factors affect the weld:
o Torch Tip Size. The torch tip size should be used to control the weld bead
width, penetration, and speed. Penetration is the depth into the base metal
that the weld fusion or melting extends from the surface, excluding any
reinforcement. Because each tip size has a limited operating range, tip sizes
must be changed to suit the thickness and size of the metal being welded.
Never lower the size of the torch flame when the correct tip size is
unavailable.
o Torch Angle. The torch angle and the angle between the inner cone and the
metal have a great effect on the speed of melting and size of the molten weld
pool. The ideal angle for the welding torch is 45o degrees. As this angle
increases toward 90o, the rate of heating increases. As the angle decreases
toward 0o, the rate of heating decreases. The distance between the inner
cone and the metal should ideally be 1/8 inch to ¼ inch ( 3 – 6 mm). As this
distance increases, the rate of heating decreases; as it decreases, the
heating rate increases.
o Welding Rod Size. Welding rod size and torch manipulations can be used to
control the weld bead characteristics. A larger-size welding rod can be used
to cool the molten weld pool, increase buildup, and reduce penetration. The
torch can be manipulated so that the direct heat from the flame is flashed off
the molten weld pool for a moment to allow it to cool.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

QUALIFICATION : FARM EQUIPMENT MECHANIC NC II
UNIT OF COMPETENCY : SERVICE, REPAIR AND MAINTAIN SMALL ENGINES
MODULE TITLE : Performing Welding, Riveting and Soldering
LEARNING OUTCOME #3 : Perform riveting applications

ASSESSMENT CRITERIA

1. The basics of riveting; the importance of the strength of the rivet and the layout of
the rivet holes;

2. The proper way to drill holes for rivet application;

3. The proper way of using clecos to ensure quality rivets; and,

4. The proper way of applying rivets.

RESOURCES Tools and Instruments Supplies and Materials
Equipment and Facilities
1. Electric hand drill 1. Insertion pliers 1. Power sources
2. Hand riveter 2. Metals
3. Riveter heads 3. Clecos or clamps
4. Rubber washer

REFERENCE MATERIALS

Alerich, Walter N. and Stephen L.Herman, “Electric Motor Control Manual”, published by
Thomas Delmar Learning (ISBN #0766861643).

Brereton, G. J., DeAraujo, A. & Bertrand, E., "Effects of Ambient Conditions on the
Emissions of a Small Carbureted Four-Stroke Engine" SAE Paper 961739, SAE Off-
Highway and Powerplant Congress, Indianapolis, Aug 1996.

Brereton, G. J., Morrison, K., Chishty, H. A., Schwartz, G. & Patterson, D. J.,"Measured
emissions of small engines under steady state and transient operation" SAE Paper 941806,
SAE Off-Highway and Powerplant Congress, Milwaukee, Sept 1994.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

Brereton, G.J., E. Bertrand, & L. Macklem, "Effects of Changing Ambient Humidity and
Temperature on the Emissions of Carbureted Two- and Four-Stroke Hand-Held Engines"
SAE Paper 97P-382.

Briggs & Stratton. “4-Stroke, Single Cylinder Horizontal Crankshaft Repair Manual.”

Fischer, H. & Brereton, G. J., "Fuel Injection Strategies for Minimizing Cold-Start
Hydrocarbon Emissions" SAE Paper 970040.

Kaiser, Joe. “Electric Power: Motors, Controls, Generators, Transformers: A Manual”,
published by Goodheart-Wilcox, (ISBN # 1-56637-362-2).

Sun, X., Brereton, G. J., Morrison, K.& Patterson, D. J., "Emissions analysis of small utility
engines" SAE Paper 952080, SAE Off-Highway and Powerplant Congress, Milwaukee,
Sept 1995. (Also printed in the SAE Publication SP-1112 `Design and Emissions of Small
Two- and Four-Stroke Engines,' SAE, 1995 and as a featured article in the SAE publication:
`Off-Highway Engineering', Jan 1996, and to appear in the SAE Journal of Engines)

Sun, X., Assanis, D. & Brereton, G. J., "Assessment of Alternative Strategies for Reducing
Hydrocarbon and Carbon Monoxide Emissions from Small Two-Stroke Engines" SAE
Paper 960743, SAE Congress, Detroit, February 1996. (Also printed in SAE SP-1131,
1996) 1995.

Sun, X., Assanis, D. & Brereton, G. J., "Numerical Modeling and Experimental Validation of
Steady-State Hydrocarbon Emissions from Small Utility Four-Stroke Engines" ASME
Internal Combustion Engines Division Meeting, Akron, 1996.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

Learning Outcome # 3: Perform riveting applications

LEARNING ACTIVITIES SPECIAL INSTRUCTIONS

1. Read and study carefully the information:

• Information sheet # 3-1: “Riveting” Read more on the topics of riveting and
• Information sheet # 3-2: “The Installation and applications.

installation”

2. Perform Job sheet # 3-1: Installing rivets Please refer to Job Sheet #3-1 for more
detailed information and follow the
instructions.

3. Answer Self-Check # 3-1. Read Self-Check # 3-1 questions and
write down your answers.

4. Check your answers. Refer to Answer Key # 3-1 and check if
you got the right answers.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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INFORMATION SHEET # 3-1

RIVETING

INTRODUCTION

This Section will focus on riveting, the choice of rivet and how to apply rivets properly. It
covers the basics of riveting; the importance of the strength of the rivet and the layout of the
rivet holes; the proper way to drill holes for rivet application; the proper way of using clecos
to ensure quality rivets; and, the proper way of applying rivets.

BASICS OF RIVETING

When you are building or repairing metal, the question of how to join two pieces of metal or
material is one of the first decisions the designer, builder, or maintainer has to answer.
Common methods of joining anything together include nuts and bolts, screws, and rivets. A
key element in this decision is how often the parts must be taken apart. If you need to
separate the two pieces of metal frequently, you probably would want to use a bolt and nut
or possibly a screw. For a more permanent attachment or connection, you might want to
use a rivet. The reason is highlighted in Webster’s Ninth New Collegiate Dictionary which
defines a rivet by saying “a headed pin or bolt of metal used for uniting two or more pieces
by passing the shank through a hole in each piece and then beating or pressing down the
plain end so as to make a second head.” Once a beaten (driven) or pressed, a second
head is formed on a rivet; a rivet is not something you can easily remove and replace.

Installing rivets involves two distinct actions. One is the proper selection of the rivet to be
installed. The second is the proper methodology. This includes mechanical skills and a
certain amount of ability.

• STRENGTH OF THE RIVET

The basic science is the calculation of what kind of rivet to use and how strong
should it be. Rivet strength is one of the most important factors in repairing
something. All repairs should be made using the same type and thickness of
material that was used in the original structure. If the original skin had corrugations
or flanges for rigidity, these must be preserved and strengthened. If a flange or
corrugation is dented or cracked, the material loses much of its rigidity, and it must
be repaired in such a way that will restore its rigidity, stiffness, and strength.”

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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• RIVET LAYOUT

There are guidelines specifying how the rivets are to be laid out. There are minimum
distances from the edge of a sheet of metal to the center of the rivet hole. Then
there are minimum and maximum recommended spacing distances between rivet
centers. Offsetting adjoining rivets makes the repair stronger than if the rivets are
placed side by side. Offsetting rows of rivets minimizes the lost of strength of the
base material in closely spaced rivets compared to adjoining rivets.

In some rivet layouts, such as circles, the installation data requires that specified
angles be maintained between the rivets. So not only do you have to understand
basic math and enough science to understand the metal and design strength
requirements used in the job, but you need a minimum understanding of geometry
and layout. All of which must be understood before you drill your first installation hole
or insert your first rivet.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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INFORMATION SHEET # 3-2

THE INSTALLATION

• DRILLING

Riveting also means drilling the properly sized hole and, if removing a rivet, following
the proper procedures. You must drill the proper size hole when installing new
rivets and it is important to avoid damaging or making a rivet hole larger when
removing a rivet. The basic rule is that the properly installed rivet should fail before
the underlying metal rips. Rivets are easier and cheaper to replace than the
underlying metal. This requirement sets the maximum strength for a rivet and a
repair. Too strong a rivet and layout and the underlying metal fails, too weak a rivet
and layout and the joint fails.

You'll need a standard "hardware store" electric hand drill. Preferably, use a high
speed drill (2,500+ RPM), which makes drilling quicker and easier. A variable speed
drill is often easier to use. Place a Rubber Washer at the drill bit shank - this way
when you drill through a hole, the rubber washer will protect the material from being
dented by the steel "chuck" of the drill. You'll also need a number of drill bits: Use
the "numbered" drill sizes for rivet holes (which provide a slightly larger hole than the
rivet size): Most drilling requires the #20 and 30 drill bit sizes, so get a few of each.
Quality bits will stay sharper longer (making drilling easier).

Hold the hand drill perpendicular to the material being drilled. Always keep drill-bits
sharp (minimizes de-burring). Make sure that you are drilling the hole the proper size
(verify drawings), and correct location. Balance the drill with both hands so that you
have full control of the drill (avoiding "wandering" of the drill). Don't drill the same
hole over more than required, as that will increase the size of the hole. You don't
need to center-punch where you will drill - a well marked spot will suffice. Adding a
rubber washer by the shank will prevent damaging the material as you drill a hole
through.

• THE CLECO

A Cleco is a small, spring-loaded clamp which is inserted into a rivet hole between
two metal sheets by a special tool that looks somewhat like a pair of pliers. The
spring loaded Cleco has an expandable tip that locks itself into the hole when
pressure is released by the insertion pliers. The special pair of pliers compresses the
Cleco’s spring, which allows the tip to be extended and inserted and later removed
from the hole. In a major job, you can have dozens or hundreds of Clecos holding

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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your sheet metal together. During the riveting process, you remove a Cleco and
install the rivet, and you go on to the next Cleco There are different sizes of Clecos
for different size rivet holes. Each type of standard Cleco fits a specific sized hole.
Normally each size of Cleco is color coded for ease of use. There are several types
of devises used to hold material together. Clamps and special long-reach Clecos are
used when needed. The important thing is to ensure that all of the holes in both
sheets of metal are in alignment and that the parts are tightly held together.

• BLIND RIVETING

The blind rivets are set with a standard hand riveter, with customized heads (nose
bushings piece). Blind rivets are very easy to set, and require access from one side
only (compared to solid rivets which require access from both sides). Hold the hand
riveter perpendicular to the material as you pull a rivet, pushing down on the riveter
(against the material) as you squeeze. Make sure material is de-burred before
riveting (all surfaces, both sides).

o Hand Riveter: For riveting, you only need a simple hand riveting tool. You do not
need a pneumatic riveting hammer and bucking bars, as all riveting is with blind
rivets (that means that riveting is very easy, quiet, and only a one-man job). If
you don't already have a "pop" riveter, purchase a light-weight heavy-duty
professional model. If you have an air compressor, you may want to use a
pneumatic rivet puller.

o Riveter Heads (changeable Nose Bushing piece)

A rivet can always be taken out: To drill out an existing rivet, drill out the rivet head
without drilling through the hole. Then, using a nail, hammer the stem of the rivet out
of the hole. This will not enlarge the rivet hole.

When there is a choice, the rivet head should be located on the side of the thinnest
material riveted together, or on the outside of the item being riveted. There is no
need to flush rivet.

There is a certain art to making a good rivet head. A standard solid-shaft rivet
consists of a factory-formed head and a shaft of a given diameter and length that
you either drive with an air-powered rivet gun to form the second rivet head or “shop
head” using the correct rivet set, or you can use a squeeze-type riveting tool to
compress the rivet and form a second rivet head. A correctly sized rivet set’s “face”
should slightly exceed the “face” of the rivet to avoid damaging the factory-formed
head of the rivet. So far, so good.

Generally speaking, a rivet is properly formed when the thickness of the formed
head or “shop head” is equal to a minimum of one half of the diameter of the rivet

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and the width of that formed head is a minimum of one and a half diameters. The
formed head must be vertical and centered on the center of the rivet. The rivet or
surrounding metal cannot be damaged or the rivet too loose or too tight in the hole.
For example, a “smiley” is great on a T-shirt, but one is bad on a rivet or surrounding
surface. A smiley is where the riveting set cuts either the rivet or underlying metal
and forms what looks like a smile or semicircular cut in the rivet or metal.

Common names given to riveting problems include rivet driven at a slant, dolly head
at a slant, one side of the rivet is flat, body of rivet too short, rivet not pulled tight or
metal plates not closed, rivet too tight or metal plates bulged because of poor fit,
riveting tool damages metal, or rivet head cracked because the rivet was too hard
when driven.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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JOB SHEET # 3-1

Title Installing rivets
Purpose To enable the participants to understand and learn
new knowledge and skills on riveting and its
Equipment, tools, materials applications.
Precautions Electric hand drill, rubber washer, clecos, hand
riveter, riveter heads, metals
Preferably, use a high speed drill (2,500+ RPM),
which makes drilling quicker and easier. A
variable speed drill is often easier to use.

Procedures

Installing rivets involves two distinct actions. One is the proper selection of the rivet to be
installed. The second is the proper methodology.

Step # 1. Properly select the rivet to be installed.

• STRENGTH OF THE RIVET

The basic science is the calculation of what kind of rivet to use and how strong should it
be. Rivet strength is one of the most important factors in repairing something. All repairs
should be made using the same type and thickness of material that was used in the
original structure. If the original skin had corrugations or flanges for rigidity, these must be
preserved and strengthened. If a flange or corrugation is dented or cracked, the material
loses much of its rigidity, and it must be repaired in such a way that will restore its rigidity,
stiffness, and strength.”

Step # 2. Observe the guidelines specifying how the rivets are to be laid out.
There are minimum distances from the edge of a sheet of metal to the center of the rivet
hole. Then there are minimum and maximum recommended spacing distances between
rivet centers. Offsetting adjoining rivets makes the repair stronger than if the rivets are
placed side by side. Offsetting rows of rivets minimizes the lost of strength of the base
material in closely spaced rivets compared to adjoining rivets.

In some rivet layouts, such as circles, the installation data requires that specified angles
be maintained between the rivets. So not only do you have to understand basic math and
enough science to understand the metal and design strength requirements used in the
job, but you need a minimum understanding of geometry and layout. All of which must be
understood before you drill your first installation hole or insert your first rivet.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

Step #3. Drilling

Riveting also means drilling the properly sized hole and, if removing a rivet, following the
proper procedures. You must drill the proper size hole when installing new rivets and it is
important to avoid damaging or making a rivet hole larger when removing a rivet. The
basic rule is that the properly installed rivet should fail before the underlying metal rips.
Rivets are easier and cheaper to replace than the underlying metal. This requirement sets
the maximum strength for a rivet and a repair. Too strong a rivet and layout and the
underlying metal fails, too weak a rivet and layout and the joint fails.

Place a Rubber Washer at the drill bit shank - this way when you drill through a hole, the
rubber washer will protect the material from being dented by the steel "chuck" of the drill.
You'll also need a number of drill bits: Use the "numbered" drill sizes for rivet holes (which
provide a slightly larger hole than the rivet size): Most drilling requires the #20 and 30 drill
bit sizes, so get a few of each. Quality bits will stay sharper longer (making drilling easier).

Hold the hand drill perpendicular to the material being drilled. Always keep drill-bits sharp
(minimizes de-burring). Make sure that you are drilling the hole the proper size (verify
drawings), and correct location. Balance the drill with both hands so that you have full
control of the drill (avoiding "wandering" of the drill). Don't drill the same hole over more
than required, as that will increase the size of the hole. You don't need to center-punch
where you will drill - a well marked spot will suffice. Adding a rubber washer by the shank
will prevent damaging the material as you drill a hole through.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

SELF CHECK #3-1

Q1. What are the basics of riveting: the importance of the strength of the rivet and the
layout of the rivet holes?

Q2. What is a cleco?
Q3. What kind of electric drill do you need in drilling holes for rivets?

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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ANSWER KEY #3-1

Q1. What are the basics of riveting: the importance of the strength of the rivet and
the layout of the rivet holes?

Answer:

• STRENGTH OF THE RIVET

The basic science is the calculation of what kind of rivet to use and how strong
should it be. Rivet strength is one of the most important factors in repairing
something. All repairs should be made using the same type and thickness of
material that was used in the original structure. If the original skin had corrugations
or flanges for rigidity, these must be preserved and strengthened. If a flange or
corrugation is dented or cracked, the material loses much of its rigidity, and it must
be repaired in such a way that will restore its rigidity, stiffness, and strength.”

• RIVET LAYOUT

There are guidelines specifying how the rivets are to be laid out. There are minimum
distances from the edge of a sheet of metal to the center of the rivet hole. Then
there are minimum and maximum recommended spacing distances between rivet
centers. Offsetting adjoining rivets makes the repair stronger than if the rivets are
placed side by side. Offsetting rows of rivets minimizes the lost of strength of the
base material in closely spaced rivets compared to adjoining rivets.

Q2. What is a cleco?

Answer
A Cleco is a small, spring-loaded clamp which is inserted into a rivet hole between
two metal sheets by a special tool that looks somewhat like a pair of pliers. The
spring loaded Cleco has an expandable tip that locks itself into the hole when
pressure is released by the insertion pliers. The special pair of pliers compresses the
Cleco’s spring, which allows the tip to be extended and inserted and later removed
from the hole. In a major job, you can have dozens or hundreds of Clecos holding
your sheet metal together. During the riveting process, you remove a Cleco and
install the rivet, and you go on to the next Cleco There are different sizes of Clecos
for different size rivet holes. Each type of standard Cleco fits a specific sized hole.
Normally each size of Cleco is color coded for ease of use. There are several types
of devises used to hold material together. Clamps and special long-reach Clecos are
used when needed. The important thing is to ensure that all of the holes in both
sheets of metal are in alignment and that the parts are tightly held together.

Q3. What kind of electric drill do you need in drilling holes for rivets?

Answer: You need a special high speed drill with 2500 +RPM to make drilling easier.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
63
10/24/ 2004 10/20/ 2005

QUALIFICATION : FARM EQUIPMENT MECHANIC NC II
UNIT OF COMPETENCY : SERVICE, REPAIR AND MAINTAIN SMALL ENGINES
MODULE TITLE : Performing Welding, Riveting and Soldering
LEARNING OUTCOME #4 : Perform soldering

ASSESSMENT CRITERIA

1. The basics of soldering: the advantages of soldering, its general applications, and
the required joint strengths;

2. The different metals used as soldering fillers and fluxes; and,

3. The proper procedures of performing soldering operations.

RESOURCES Tools and Instruments Supplies and Materials
Equipment and Facilities
1. Torch 1. Solder alloys such as.
2. Solder Tin-lead or tin-antimony
solder wire
2. A piece of aluminum
plate,
3. Steel wool,
4. Fluxes,
5. Filter metals

REFERENCE MATERIALS

Alerich, Walter N. and Stephen L.Herman, “Electric Motor Control Manual”, published by
Thomas Delmar Learning (ISBN #0766861643).

Brereton, G. J., DeAraujo, A. & Bertrand, E., "Effects of Ambient Conditions on the
Emissions of a Small Carbureted Four-Stroke Engine" SAE Paper 961739, SAE Off-
Highway and Powerplant Congress, Indianapolis, Aug 1996.

Brereton, G. J., Morrison, K., Chishty, H. A., Schwartz, G. & Patterson, D. J.,"Measured
emissions of small engines under steady state and transient operation" SAE Paper 941806,
SAE Off-Highway and Powerplant Congress, Milwaukee, Sept 1994.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

Brereton, G.J., E. Bertrand, & L. Macklem, "Effects of Changing Ambient Humidity and
Temperature on the Emissions of Carbureted Two- and Four-Stroke Hand-Held Engines"
SAE Paper 97P-382.

Briggs & Stratton. “4-Stroke, Single Cylinder Horizontal Crankshaft Repair Manual.”

Fischer, H. & Brereton, G. J., "Fuel Injection Strategies for Minimizing Cold-Start
Hydrocarbon Emissions" SAE Paper 970040.

Kaiser, Joe. “Electric Power: Motors, Controls, Generators, Transformers: A Manual”,
published by Goodheart-Wilcox, (ISBN # 1-56637-362-2).

Sun, X., Brereton, G. J., Morrison, K.& Patterson, D. J., "Emissions analysis of small utility
engines" SAE Paper 952080, SAE Off-Highway and Powerplant Congress, Milwaukee,
Sept 1995. (Also printed in the SAE Publication SP-1112 `Design and Emissions of Small
Two- and Four-Stroke Engines,' SAE, 1995 and as a featured article in the SAE publication:
`Off-Highway Engineering', Jan 1996, and to appear in the SAE Journal of Engines)

Sun, X., Assanis, D. & Brereton, G. J., "Assessment of Alternative Strategies for Reducing
Hydrocarbon and Carbon Monoxide Emissions from Small Two-Stroke Engines" SAE
Paper 960743, SAE Congress, Detroit, February 1996. (Also printed in SAE SP-1131,
1996) 1995.

Sun, X., Assanis, D. & Brereton, G. J., "Numerical Modeling and Experimental Validation of
Steady-State Hydrocarbon Emissions from Small Utility Four-Stroke Engines" ASME
Internal Combustion Engines Division Meeting, Akron, 1996.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
Developed Revised:
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10/24/ 2004 10/20/ 2005

Learning Outcome # 4: Perform soldering SPECIAL INSTRUCTIONS
LEARNING ACTIVITIES

1. Read and study carefully the information:

• Information sheet # 4-1: “Soldering” Read more on the topic of soldering and its
applications to prepare you for the next task
• Information sheet # 4-2: “Soldering to be performed under Job Sheet #4-1.
filler metals and fluxes”

• Information sheet # 4-3: “Soldering
procedures”

2. Perform Job sheet # 4-1: Demonstrate Please refer to Job Sheet #4-1 for more
soldering Procedures detailed information and follow the
instructions.

3. Answer Self-Check # 4-1. Read Self-Check # 4-1 questions and write
down your answers.

4. Check your answers. Refer to Answer Key # 4-1 and check if
you got the right answers.

Code No. Performing Welding, Riveting and Soldering Date: Date Page #
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INFORMATION SHEET # 4-1

SOLDERING

INTRODUCTION

This Section will deal with the basic of soldering, the advantages and general applications
of soldering; The different types of metals used as soldering fillers and fluxes; the proper
way of performing soldering operations.

SOLDERING BASICS

Soldering is classified as a liquid-solid bonding process. Liquid means that the filler metal
is melted; solid means that the base material or materials are not melted. The phase is the
temperature at which bonding takes place between the solid base material and the liquid
filler metal.

• Advantages of Soldering. There are several reasons for the widespread use of

soldering:

o Low Distortion/Stress on Base Metal. Because the pieces of base metal are
joined at a relatively low temperature at which the base metal does not melt;
there is less risk of distortion and stress in the base metal;

o Good Penetration. Because of their excellent flow characteristics, soldering
processes penetrate well into narrow gaps and are therefore very convenient
for filling gaps in body seams. Because the base metal does not melt, it is
possible to join otherwise incompatible metals, such as copper to steel or
stainless steel to mild steel;

o Easy to Learn. The soldering technique takes relatively little time and skill to
learn;

o Flexibility. Parts can be easily repositioned or even disassembled later by
reheating the joint; and,

o Compatibility. Parts of varying thicknesses can be joined without burning or
overheating.

• General Applications. Soldering methods are grouped according to the method

with which heat is applied. Here, we cover only torch soldering. Some advantages
of using a torch include the following:

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o Versatility. Using a torch is the most versatile method. Both small and large
parts in a wide variety of materials can be joined with the same torch.

o Portability. A torch is very portable. Any place a set of cylinders can be taken
or anywhere the hoses can be pulled into can be soldered with a torch.

o Speed. The flame of the torch is one of the quickest ways of heating the
material to be joined, especially on thicker sections.

Some of the disadvantages of using a torch include the following:

o Overheating. When using a torch, it is easy to overheat or burn the parts,
flux, or filler metal.

o Skill. A high level of skill with a torch is required to produce consistently good
joints.

o Fires. It is easy to start a fire if a torch is used around combustible materials.

• Joint Strength. The tensile strength of a joint is its ability to withstand being pulled

apart.

o Tensile Strength. If a few drops of water are placed between 2 smooth flat
panes of glass and the panes are pressed together, a tensile load is required
to pull the panes of glass apart. Water, which has no tensile strength of its
own, has added tensile strength to the glass joint. The glass is being held
together by the surface tension of the water. As the space between the
pieces of glass decreases, the tensile strength increases.

o Tensile Strength of Joints. A soldered joint can be made that has a tensile
strength 4 or 5 times higher than the filler metal itself. Since the strength of
the soldering material is less than the base metal, the shape and the
clearance of the joint are extremely important. Joint strength depends on the
surface area of the pieces to be joined; so make the joint overlap as wide as
possible.

o Overlaps. Even when the items being joined are of the same material, the
soldered surface area must be larger than that of the welded joint. As a
general rule, the overlapping portion must be at least 3 times wider than the
panel thickness.

o Joint Preparation. Joint preparation is very important to a successful soldered
part. The surface must be free of all oil, dirt, paint, oxides, or any other
contaminants. The surface can either be mechanically cleaned or chemically

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cleaned. Soldering should start as soon as possible after the parts are
cleaned to prevent any additional contamination of the joint.

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INFORMATION SHEET # 4-2

SOLDERING FILLER METALS AND FLUXES

The type of filler metal to use for a specific joint should be selected by considering as many
as possible criteria including: material being joined, strength required, joint design,
availability and cost, appearance, heating process, etc. The technician must decide which
factors they consider most important and then base their selection on that decision.

Soldering metals are alloys, that is, a mixture of two or more metals. Each alloy is available
in a variety of different percentage mixtures. Some mixtures are stronger, and some melt
at lower temperatures than others. Each one has specific properties.

• Soldering Alloys. Soldering alloys are usually identified by their major alloying

elements. In many cases, a base material can be joined by more than one solder
alloy. The most common alloys in use are the tin-lead or tin-antimony solders. Both
solders have low melting temperatures.

o Tin-Lead. This is the most popular solder and is the least expensive one. An
alloy of 61.9% tine and 38.1% lead melts at 362oF (183oC) and has no paste
range. Paste range is the temperature range in which a metal is partly solid
and partly liquid.

Tin-lead solders are most commonly used on electrical connections. But it
must never be used for water piping. Most health and construction codes will
not allow tin-lead solders for use on water or food-handling equipment.

o Tin-Antimony. This family of solder has a higher tensile strength and lower
creep than the tin-lead solders. The most common alloy is 95/5, that is 95%
tin and 5% antimony. This is often referred to as the “hard solder” and is the
most common solder used in plumbing because it is lead-free. The use of C
flux, which is a mixture of flux and small flakes of solder, makes it easy to
fabricate quality joints. This mixture of flux and solder will draw additional
solder into the joint as it is added.

• Fluxes. Fluxes used in soldering have 3 major functions:

— They must remove any oxide that form as a result of heating the parts;
— They must promote wetting; and
— They should aid in capillary action.

The flux, when heated to its reacting temperature, must be thin and flow through the
gap provided at the joint. As it flows through the joint, the flux absorbs and dissolves

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oxides, allowing molten filler metal to be pulled in behind it. After the joint is
complete, the flux residue should be easily removable.

o Forms of Fluxes. Fluxes are available in many forms, such as solids,
powders, pastes, liquids, sheets, rings, and washers. They are also available
mixed with the filler metal, inside the filler metal, or on the outside of the filler
metal. The most common types of fluxes are pastes and powders. They may
be brushed on the joint before or after the materials is heated. Pastes and
powders may also be applied to the end of the rod by heating the rod and
dipping it in the flux. Most powders can be made into a paste, and some
paste can be thinned by adding distilled water or alcohol. Distilled water
should be used because tap water may contain minerals that will weaken the
flux.

o Fluxing Action. Soldering fluxes are chemical compounds such as muriatic
acid, ammonium chloride, or rosin. These compounds react to dissolve,
absorb, or mechanically break up thin surface oxides that are formed as the
parts are being heated. They must be stable and remain active through the
entire temperature range of the solder. The chemicals in the flux react with
the oxides as either acids or bases.

The reactivity of a flux is greatly affected by temperature. As the parts are
heated to the soldering temperature, the flux becomes more active. Some
fluxes are completely inactive at room temperature. Most fluxes have a
temperature range within which they are most effective. Care should be
taken to avoid overheating fluxes. If they become overheated or burned, they
will stop working as fluxes and become a contamination in the joint. If
overheating has occurred, the technician must stop and clean off the
damaged flux before continuing. If the part is to be finished in any way, the
flux must be completely removed. Otherwise it might react with the finishing
material.

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INFORMATION SHEET # 4-3

SOLDERING PROCEDURES

• Soldering Steel/Iron. The materials to be soldered must be thoroughly cleaned. A

chemical cleaner is good to use, provided it is rinsed and dried off completely. The
metals can also be cleaned by filing or wire-brushing; steel wool also works well.
After the surface has been cleaned, proceed as follows:

1. Heat the portion to be soldered. Wipe it with a cloth after heating.
2. Stir the solder paste well. Apply it with a brush to an area larger than the

build-up area.

3. Heat it from a distance.
4. Wipe the solder paste from the center to the outside.
5. Make sure the soldered portion is silver gray. If it is bluish, it has overheated.
6. If any spot is not adequately soldered, reapply the paste for additional

soldering.

When soldering, keep the following additional points in mind:

— It is wise to use a special torch for soldering. If a gas welding torch is used,
the oxygen and acetylene gas pressures must be 4.3 to 5.0 psi.

— To maintain the appropriate temperature, move the torch so that the flame
evenly heats the entire portion to be soldered. When the solder begins to
melt, remove the flame and finish with a spatula.

— When additional solder is required, the previously built-up solder must be
reheated.

If either piece of metal moves while it is cooling from its flow temperature to its
solidification temperature, the solder will form cracks and will probably fail. It is
therefore necessary to firmly support the base metals with a fixture, clamps, or the
like to make sure they do not move while the soldering operation is in progress.

A common soldering error is to use too much solder. This is wasteful because it
does not add any strength to the joint. If too much solder is used, a neat-looking
joint can still be achieved by wiping off the excess molten solder using a clean, thick
cloth. The solder should be wiped away while it is at its flowing temperature rather
that at its melting temperature. It is very important to avoid overheating the metal.

A popular use for soldering is to build up irregular surfaces to secure a smooth

finish. This method is used extensively. The irregular surface is mechanically

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cleaned, then chemically cleaned with a weak acid. A wooden paddle is sometimes
used to apply the solder to the torch-heated surfaces.

o Using Soldering Copper. Soldering copper produces very concentrated heat
while at the same time acting as a means of spreading the solder as it
adheres to the base metals. In many places, this is known as soldering iron.
It has the disadvantage of requiring reheating quite frequently. However,
electrically heated soldering coppers and internal flame-heated coppers do
not have this problem. The tip of the soldering copper must be kept clean at
all times.

One of the best applications of soldering copper is to use it for sweating a
soldered joint. This means that the two metals to be soldered together are
lapped at their joint with a previously applied film of solder on the two
contacting surfaces. These edges are then lapped, and the copper is slowly
moved along the seam, permitting the heat from the soldering copper to
penetrate through the metal and fuse the solder films together. The resulting
joint is strong and neat. This method is recommended when a high-quality,
leakproof joint is desired and for difficult-to-solder joints.

o Phase Range. Almost all of the alloys used for soldering have a phase range.
A paste range is the temperature range in which a metal is partly solid and
partly liquid as it is heated or cooled. As the joined part cools through the
paste range, it is important that the part not be moved. If the part is moved,
the solder may crumble like dry clay, destroying the bond.

• Soldering Aluminum. Using a properly lit and adjusted torch, a piece of aluminum

plate, steel wool, flux, and tin-lead or tin-antimony solder wire, you will tin both the
pieces of aluminum with solder, and then join them together.

The surface of the aluminum must be clean and free of paint, oils, dirt, and coatings
such as anodizes. Hold the flame on the aluminum until it warms up slightly. Hold
the solder in the flame and allow a small amount to melt and drop on the aluminum
plate. Do not add flux yet. Move the flame off the plate and rub the liquid solder
with the steel wool. Be careful not to burn your fingers or allow the flame to touch
the steel wool. The solder should be stuck in the steel wool when it is lifted off the
plate. Alternately heat the plate and rub it with the steel wool solder. When the
plate becomes hot enough, it will melt the solder, and the solder will tin the
aluminum surface.

Once both aluminum plates have been tinned, place them so that they are touching
each other. Heat the two until the solder melts and flows out from between the two
plates. When the parts cool, check the bond by trying to break the joint apart.

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This process will work on other types of metals that have strong oxide layer that
prevents the solder from bonding. By breaking the oxide layer free with the
mechanical action of the steel wool, the metals can be joined. This process cal also
be used to make a copper patch over an aluminum tube, such as those used in air-
conditioning. Turn off the cylinders, bleed the hoses, back out the regulator
adjusting screw, and clean up your work area when you are finished.

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JOB SHEET # 4-1

Title Demonstrate soldering procedures
Purpose To enable the participants to gain more
knowledge and skills in soldering and its
Equipment, tools, materials applications,
Precautions Soldering alloys, filler metals, fluxes, aluminum
metal plate, steel wool, solder

Procedures

Soldering Steel /Iron

1. Clean the materials to be soldered. Use a chemical cleaner but thoroughly rinse and
dry it off completely
2. Stir the solder paste well. Apply it with a brush to an area larger than the build-up
area.
3. Heat it from a distance.
4. Wipe the solder paste from the center to the outside.
5. Make sure the soldered portion is silver gray. If it is bluish, it has overheated.
If any spot is not adequately soldered, reapply the paste for additional soldering.
When soldering, keep the following additional points in mind:

— It is wise to use a special torch for soldering. If a gas welding torch is used,
the oxygen and acetylene gas pressures must be 4.3 to 5.0 psi.

— To maintain the appropriate temperature, move the torch so that the flame
evenly heats the entire portion to be soldered. When the solder begins to
melt, remove the flame and finish with a spatula.

— When additional solder is required, the previously built-up solder must be
reheated.

Soldering Aluminum

1. Use a properly lit and adjusted torch, a piece of aluminum plate, steel wool, flux,
and tin-lead or tin-antimony solder wire when you will tin both the pieces of
aluminum with solder, and then join them together.

2. Clean the surface of the aluminum to make it clean and free of paint, oils, dirt, and
coatings such as anodizes.

3. Hold the flame on the aluminum until it warms up slightly. Hold the solder in the
flame and allow a small amount to melt and drop on the aluminum plate. Do not
add flux yet. Move the flame off the plate and rub the liquid solder with the steel

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wool. Be careful not to burn your fingers or allow the flame to touch the steel wool.
The solder should be stuck in the steel wool when it is lifted off the plate.
Alternately heat the plate and rub it with the steel wool solder. When the plate
becomes hot enough, it will melt the solder, and the solder will tin the aluminum
surface.
4. Place the aluminum plates together so that they are touching each other once both
plates have been tinned,. Heat the two until the solder melts and flows out from
between the two plates. When the parts cool, check the bond by trying to break
the joint apart.
5. Turn off the cylinders, bleed the hoses, back out the regulator adjusting screw, and
clean up your work area when you are finished.

Safety Precautions
1. If either piece of metal moves while it is cooling from its flow temperature to its
solidification temperature, the solder will form cracks and will probably fail. It is
therefore necessary to firmly support the base metals with a fixture, clamps, or the
like to make sure they do not move while the soldering operation is in progress.
2. A common soldering error is to use too much solder. This is wasteful because it
does not add any strength to the joint. If too much solder is used, a neat-looking
joint can still be achieved by wiping off the excess molten solder using a clean,
thick cloth. The solder should be wiped away while it is at its flowing temperature
rather that at its melting temperature. It is very important to avoid overheating the
metal.

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SELF-CHECK #4-1

Q1. What are the advantages of soldering?
Q2. What are the 3 major functions of fluxes used for soldering?

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ANSWER KEY # 4-1

Q1. What are the advantages of soldering?

Answer:

• . There are several reasons for the widespread use of soldering:

o Low Distortion/Stress on Base Metal. Because the pieces of base metal are
joined at a relatively low temperature at which the base metal does not melt;
there is less risk of distortion and stress in the base metal;

o Good Penetration. Because of their excellent flow characteristics, soldering
processes penetrate well into narrow gaps and are therefore very convenient
for filling gaps in body seams. Because the base metal does not melt, it is
possible to join otherwise incompatible metals, such as copper to steel or
stainless steel to mild steel;

o Easy to Learn. The soldering technique takes relatively little time and skill to
learn;

o Flexibility. Parts can be easily repositioned or even disassembled later by
reheating the joint; and,

o Compatibility. Parts of varying thicknesses can be joined without burning or
overheating.

Q2. What are the 3 major functions of fluxes used for soldering?

Answer:

• Fluxes used in soldering have 3 major functions:

— They must remove any oxide that form as a result of heating the parts;
— They must promote wetting; and
— They should aid in capillary action.

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Performance Assessment

EVIDENCE PLAN

Sector: AUTOMOTIVE INDUSTRY

Unit of Competency: Service, Repair and Maintain Small Engines

Module Title: Performing Welding, Riveting and Soldering

Ways in which evidences will be collected:

(tick the column) Interview
Demonstration with
The evidence must show that the candidate … Questioning
Observation with
Questioning
Written Test
Presentation of Final
Product
Third Party Report
Portfolio

1. Can explain and discuss the basics of Shielded X X
Metal Arc Welding, types of power sources, Arc X
blows, and the proper use of basic welding X
equipment; X X
X X
2. Demonstrate the proper location and setting for X
welding jobs, and the basic techniques and
practices to ensure good quality welding;

3. Demonstrate making the different types of
welding weave patterns and their respective
uses and applications

4. Discuss and explain the basics of oxyacetylene
welding, the safety features and gadgets ;

5. Discuss the proper care and maintenance of
basic equipment such as the torch, tip, hoses,
and fittings;

6. Identify the proper precautions to take to prevent
backfires and flashbacks;

7. Performing actual oxyacetylene welding
operations.

8. Explain the basics of riveting; the importance of
the strength of the rivet and the layout of the
rivet holes

9. Demonstrate the proper way to drill holes for
rivet application;

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10. Explain the proper way of using clecos to ensure X
quality rivets; and, X
X
11. Discuss the proper way of applying rivets.
X
12. Explain the basics of soldering: the advantages X
of soldering, its general applications, and the
required joint strengths;

13. Identify the different metals used as soldering
fillers and fluxes; and,

14. Discuss the proper procedures of performing
soldering operations.

Note: *Critical aspects of competency

Prepared by: Date:
Date:
Instructor
Supervisor

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PERFORMANCE TEST

Learner’s Name Date:

Competency: Performing welding, riveting and Test Attempt
soldering 1st 2nd 3rd

OVERALL EVALUATION

Directions: Level PERFORMANCE LEVELS
CALL Achieved
INSTRUCTOR. 4 - Can perform this skill without supervision and
Ask instructor with initiative and adaptability to problem situations
to assess your
performance in 3 - Can perform this skill satisfactorily without
the following assistance or supervision
critical task and
performance 2 - Can perform this skill satisfactorily with
criteria below. assistance and/ or supervision

You will be rate 1 – Can perform parts this skill satisfactorily, but
based on the requires considerable assistance and/or supervision.
overall
evaluation on
the right side.

Instructor will initial the level achieved.

PERFORMANCE STANDARDS Yes No N/A
For acceptable achievement, all items should receive a
“Yes” or “No response”
1. Explain the basics of Shielded Metal Arc Welding,

types of power sources, Arc blows, and the proper use
of basic welding equipment;

2. Demonstrate the proper location and setting for
welding jobs, and the basic techniques and practices
to ensure good quality welding;

3. Make the different types of welding weave patterns
and their respective uses and applications.

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4. Discuss the basics of oxyacetylene welding, the safety
features and gadgets ;

5. Explain the proper care and maintenance of basic
equipment such as the torch, tip, hoses, and fittings;

6. The proper precautions to take to prevent backfires
and flashbacks;

7. Performing actual oxyacetylene welding operations.
8. Discuss the basics of riveting; the importance of the

strength of the rivet and the layout of the rivet holes;

9. Demonstrate the proper way to drill holes for rivet
application;

10. Show the proper way of using clecos to ensure quality
rivets;

11. Discuss the proper way of applying rivets.
12. Explain the basics of soldering: the advantages of

soldering, its general applications, and the required
joint strengths;

13. Identify the different metals used as soldering fillers
and fluxes;

14. Demonstrate the proper procedures of performing
soldering operations

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Assessment Instruments

DEMONSTRATION WITH QUESTIONING

Candidate’s name Farm Equipment Mechanic NC II
Assessor’s name
Competency Assessment Title
Qualification
Date of Assessment
Time of Assessment
Instructions for Demonstration

Given the following materials tools and equipment, the candidate must be able to
Maintain small engines
Equipment, tools and materials : Solder, soldering alloys and fluxes, special service tools

OBSERVATION Tick (/) to show if evidence is
Demonstrated.

During the demonstration of skills, did the Yes No Actual
5.0
candidate: 1.0-3.0

1. Know how to use the electronic hand drill

2. Show how to layout the rivets
3. Drill the proper size of holes in riveting
4. Demonstrate the proper location and

setting of welding jobs
5. Observe the safety practices in

Occupational Safety and Health
standards in the workplace
6. Explain the proper way of applying rivets
7. Demonstrate the proper use of clecos

The candidate’s demonstration was :

Rating ________

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DEMONSTRATION (continued)

Questions Satisfactory Response

The candidate should answer the following Yes No
questions:
1. What are the advantages of soldering?
2. What are the 3 major functions of fluxes used

for soldering?
3. What kind of electric drill do you need in drilling

holes for rivets?

4. Enumerate certain basic equipment common to
all gas welding.

5. What device or devices are used to prevent
excessively high pressures from damaging the
regulator?

6. What are the types of power sources that are
required by arc welding?

The candidate’s underpinning knowledge was:

Rating_______

Feedback to candidate

The candidate’s overall performance was: Date:
Rating:__________ Date:
Candidate’s signature

Assessor’s signature:

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WRITTEN TEST

Candidate’s name: Competency Response

Unit of competency
Competency Standards
Questions

YES NO

1. What is SMAW ?
2. Describe the cables used for welding.
3. What is oxyacetylene welding?
4. What are the common types of oxyfuel gas torch?

Which of these offer the most flexibility?
5. What is a reverse flow valve and what is its main

purpose?
6. What are the basics of riveting: the importance of the

strength of the rivet and the layout of the rivet holes?

7. What is a cleco?

8. What are the 3 major functions of fluxes used for
soldering?

Feedback to candidate:

Acceptance answer are:

Assessor’s signature: Date:

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Record of Achievement

Module 4 Performing Welding, Riveting and Soldering
Learning Outcome # 1: Perform shielded metal arc welding
Performance Criteria

1. The basics of Shielded Metal Arc Welding, types of power sources, Arc
blows, and the proper use of basic welding equipment;

2. The proper location and setting for welding jobs, and the basic techniques
and practices to ensure good quality welding; and

3. The different types of welding weave patterns and their respective uses and
applications.

Comments
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Learner has satisfied the above performance criteria.
Learner’s signature …………………………………….
Trainer’s signature………………………………………
Date ……………………………………………………...

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Record of Achievement

Module 4 Performing Welding, Riveting and Soldering
Learning Outcome # 2: Perform oxyacetylene welding
Performance Criteria

1. The basics of oxyacetylene welding, the safety features and gadgets ;
2. The proper care and maintenance of basic equipment such as the torch, tip,

hoses, and fittings;
3. The proper precautions to take to prevent backfires and flashbacks;
4. Performing actual oxyacetylene welding operations.

Comments
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Learner has satisfied the above performance criteria.
Learner’s signature …………………………………….
Trainer’s signature………………………………………
Date ……………………………………………………...

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Record of Achievement

Module 4 Performing Welding, Riveting and Soldering
Learning Outcome # 3: Perform riveting applications
Performance Criteria

1. The basics of riveting; the importance of the strength of the rivet and the
layout of the rivet holes;

2. The proper way to drill holes for rivet application;
3. The proper way of using clecos to ensure quality rivets; and,
4. The proper way of applying rivets.

Comments
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Learner has satisfied the above performance criteria.
Learner’s signature …………………………………….
Trainer’s signature………………………………………
Date ……………………………………………………...

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Record of Achievement

Module 4 Performing Welding, Riveting and Soldering
Learning Outcome # 4: Perform soldering
Performance Criteria

1. The basics of soldering: the advantages of soldering, its general
applications, and the required joint strengths;

2. The different metals used as soldering fillers and fluxes; and,
3. The proper procedures of performing soldering operations.

Comments
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Learner has satisfied the above performance criteria.
Learner’s signature …………………………………….
Trainer’s signature………………………………………
Date ……………………………………………………...

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Learner’s Diary

Diary Notes

Record important dates, jobs undertaken and other workplace events that will assist in
providing further details to your Assessor.

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GLOSSARY

LIST OF ACRONYMS

NA Not applicable
RPL Recognition of Prior Learning
STD Standards
TESDA Technical Education Skills and Development Authority

LIST OF TERMS

Compression stroke: The piston continues to move toward the top dead center. As the
intake and exhaust valves are closed, the air in the cylinder is compressed. In diesel
engines, which have compression ratios of about 15 to 20, the pressure rises to 30 to 35
atm and the temperature is about 500°C when the piston is at the top dead center. Gas oil
which spontaneously ignites around 200°C burns readily at 500°C. Thus, the fuel injected
into the cylinder by the fuel pump immediately before the piston reaching the top dead
center ignites explosively. This is the "compression" stroke.

Damping valve: The damping valve is assembled in the end of injection pump and it
reaches the seat before arrival of delivery valve at the seat. The small orifice in the valve is
the passage of fuel to the chamber in the delivery valve holder. Accordingly, descending
velocity of the delivery valve is decreased, which prevents the negative pressure being
produced suddenly. As a result, proper injection is conducted and the engine noise is
decreased.

Delivery valve: delivery valve prevents reverse flow of the fuel.

Diesel engine : A diesel engine is an internal combustion engine, a type of heat engine.
Heat engines convert heat energy, produced by the burning of fuel into mechanical motion.
A "working fluid" is required to convert heat into work.

Forced Supply of Fuel: The camshaft rotates and pushes up the plunger. Forced supply
of the fuel is started only when the upper part of the plunger closed the fuel intake in the
course of being pushed up by the cam rotation. The fuel in the barrel is pressurized by a
very strong force, and as a result, the force of the fuel pushes up the delivery valve and the
damping valve, and then it injects the fuel into combustion chamber. This is on the stage of
"pressurized supply."

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Expansion stroke: The explosive combustion of fuel rapidly increases the pressure to 50
to 60 atm and pushes the piston down toward the bottom dead center. Combustion is
maintained as fuel injected, but the pressure is held at 50 to 60 atm because of the
increasing space created as the piston moves down. After fuel injection ends, the pressure
decreases as the piston lowers, until the piston reaches near the bottom dead center. This
is the "expansion" or "power" stroke.

Exhaust stroke: When the piston comes near the bottom dead center, the exhaust valve
opens and the expanded gas is exhausted. While the piston travels from the bottom dead
center to the top dead center, the remaining gas in the cylinder is also exhausted. This
process is the "exhaust" stroke. This process of four strokes completes one complete
round; and is repeated as long as the engine runs.

Governor mechanism. The governor is centrifugal flyweight type, which means flyweight
is fitted to the governor gear. The governor sleeve is assembled so that it may slide toward
the direction of the axis of the pump shaft, and it is in contact with the flyweight. The
governor sleeve gets in touch with the governor yoke, and through the governor lever it
makes the control rack of injection pump operate. This mechanism enables to maintain
constant operation irrespective of load variation.

Injection timing: Injection timing of this engine is fixed constant (23° before TDC)
irrespective of engine rpm. On the other hand, in starting, a proper delay from the timing for
high speed running and increased fuel injection is indispensable for effective starting, For
this purpose a notch is made at the plunger head, which reserves to delay the injection
timing by nearly 8° to facilitate starting.

Oil Filter

Oil filter is made of nylon mesh and is reusable after cleaning. As the oil flows from the
inside of the filter to the outside, be sure to clean the inside thoroughly. Clean the oil filter
every time of oil change.

Scavenging stroke: As the exhaust port opens at the end of the expansion (power) stroke
when the piston goes past the top dead center, the combustion gas begins to combustion is
not interrupted by the incomplete. The air in the crankcase compressed by descending
piston is then blown into the combustion chamber through the scavenging port and
exhausts the combustion gas through the exhaust port.

Sunction stroke: The intake valve is open when the piston is near the top dead center. As
the piston moves to the bottom dead center, pressure in the cylinder falls below the
atmospheric pressure to suck air into the cylinder until the piston goes past the bottom
dead center. The process is the "suction" stroke.

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Sunction and compression stroke: As the piston rises, pressure in the crankcase is
reduced below the atmospheric pressure to open the intake valve to allow air go into the
crankcase. As the piston approaches the top dead center, the scavenging port is closed
and air in the combustion chamber is compressed.

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REFERENCE MATERIALS

Alerich, Walter N. and Stephen L.Herman, “Electric Motor Control Manual”, published by
Thomas Delmar Learning (ISBN #0766861643).

Brereton, G. J., DeAraujo, A. & Bertrand, E., "Effects of Ambient Conditions on the
Emissions of a Small Carbureted Four-Stroke Engine" SAE Paper 961739, SAE Off-
Highway and Powerplant Congress, Indianapolis, Aug 1996.

Brereton, G. J., Morrison, K., Chishty, H. A., Schwartz, G. & Patterson, D. J.,"Measured
emissions of small engines under steady state and transient operation" SAE Paper 941806,
SAE Off-Highway and Powerplant Congress, Milwaukee, Sept 1994.

Brereton, G.J., E. Bertrand, & L. Macklem, "Effects of Changing Ambient Humidity and
Temperature on the Emissions of Carbureted Two- and Four-Stroke Hand-Held Engines"
SAE Paper 97P-382.

Briggs & Stratton. “4-Stroke, Single Cylinder Horizontal Crankshaft Repair Manual.”

Fischer, H. & Brereton, G. J., "Fuel Injection Strategies for Minimizing Cold-Start
Hydrocarbon Emissions" SAE Paper 970040.

Kaiser, Joe. “Electric Power: Motors, Controls, Generators, Transformers: A Manual”,
published by Goodheart-Wilcox, (ISBN # 1-56637-362-2).

Sun, X., Brereton, G. J., Morrison, K.& Patterson, D. J., "Emissions analysis of small utility
engines" SAE Paper 952080, SAE Off-Highway and Powerplant Congress, Milwaukee,
Sept 1995. (Also printed in the SAE Publication SP-1112 `Design and Emissions of Small
Two- and Four-Stroke Engines,' SAE, 1995 and as a featured article in the SAE publication:
`Off-Highway Engineering', Jan 1996, and to appear in the SAE Journal of Engines)

Sun, X., Assanis, D. & Brereton, G. J., "Assessment of Alternative Strategies for Reducing
Hydrocarbon and Carbon Monoxide Emissions from Small Two-Stroke Engines" SAE
Paper 960743, SAE Congress, Detroit, February 1996. (Also printed in SAE SP-1131,
1996) 1995.

Sun, X., Assanis, D. & Brereton, G. J., "Numerical Modeling and Experimental Validation of
Steady-State Hydrocarbon Emissions from Small Utility Four-Stroke Engines" ASME
Internal Combustion Engines Division Meeting, Akron, 1996.

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Acknowledgment

We acknowledge the contribution of the following project team members
™ Mr. Conrado S. Navarro for project advisory services,
™ Mr. Alvin R. Manalang for technical writing and review of outputs,
™ Ms. Yolanda C. Velez for overall technical supervision and editing,
™ Mr. Jesus Sy for IT services,
™ Mr. Romulo Oller and Ms. Mina Lim for administrative support, project
monitoring and coordination.

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