FEDERAL UNIVERSITY OF AGRICULTURE, ABEOKUTA

COLLEGEOF ENGINEERING
DEPARTMENT OF AGRICULTURAL AND BIO-RESOURCES ENGINEERING

COURSE CODE: ABE 204

COURSE TITLE: Workshop Practice
NUMBER OF UNITS: 2 Units
COURSE DURATION: Four hours (two hrs for lecture and two hrs for practical) per week.
COURSE DETAILS:
Course Lecturers: Prof. I. A. Ola and Engr V. O. Adepoju
COURSE CONTENTS:
1. Workshop safety measures.
2. Introduction to Workshop hand and powered tools emphasizing safety measures to be
taken during operation.
3. Workshop materials various gauges and measuring devices.
4. General description of the function and capabilities of grinding machine, drilling
machine, lathe machines, milling machines, shaping machines and cutting machines.
5. Practice in the use of machines.
6. Welding, bracing, soldering and riveting.
7. Carpentry: hand tools, materials, types of joints, processing of timber.
8. Manufacture of simple components using steel and wood.

COURSE REQUIREMENTS:
This is a compulsory course for all students in the College of Engineering. In view of this,
Students are expected to participate in all the lecture sessions as well as practical sessions
and have minimum of 70% attendance to be able to write the final examination.

READING LIST:

1.0 WORKSHOP SAFETY MEASURES.

Safety
Safety is the absence of risks or harm or Safety is the condition of being protected from danger
or risk which otherwise would have resulted in harm or accidents.
Health
Is a state of wellbeing, with the absence of illness or disease.
Environment: This is our surroundings which include:
1. Natural resources, air, water and land
2. Humans
3. Plants
4. Animals
5. Equipment and facilities
6. The interaction of these environmental objects with humans
1. Terminologies in Health, Safety and Environment
i. Accident
Is an unplanned or undesired event that can result in harm to people, property or the
environment.
ii. Near Miss
Is an event where no contact or exchange of energy occurred and thus did not result in personal
injury, asset loss or damage to the environment.
iii. Incident (Accident or Near Miss)
Is an unwanted occurrence capable of causing or has caused occupational illness, injury or
death to persons, property damage, environmental damage, loss of reputation of the company.
iv. Exposure
Is the measurement of time during which the subject is at risk from a hazard.
v. Fatality
Is a death due to a work-related incident or illness regardless of the time between injuries or
illness and death.
vi. Harm
Is injury, death, physical or mental ill health, damage to property, loss of production or any
combination of these.
vii. Hazard
Is a source or situation with a potential to cause harm, including human injury or ill health,
damage to property, damage to the environment, or a combination of these.
viii. Restricted Work Case
Work related injury or illness that renders the injured person unable to perform all normally
assigned work functions during a scheduled work shift or being assigned to another job on a
temporary or permanent basis on the day following the injury.
ix. Risk
Is a measure of the likelihood that the harm from a particular hazard will occur, taking into
account the possible severity of the harm.
x. Unsafe Act
Is any act or behaviour or norm that deviates from generally recognized safe way or specified
method of doing a job and increases the potential for an accident. Examples: Using knife to
unscrew faulty electrical socket, unethical arrangement of platforms to fix height related work,
etc.
xi. Unsafe Condition
Is anything or an environment or any situation that has all the capacity to harm people, property
and environment. Examples: Faulty electrical sockets, wet floor, banana peels on the floor,
trailing cables, etc.
xii. Man-hours
Total number of hours worked by workers in a workplace over a period of time.
xiii. SWL
Safe Working Load
xiv. A.L.A.R.P.
Acronym for As Low As Reasonably Practicable. It refers to a process of reducing likelihood
of occurrence of an incident for the minimization of the effects or consequences of such
incidents.
xv. Personal Protective Equipment (PPE)
All equipment and clothing intended to be utilised, which affords protection against one or
more risks to health and safety. This includes protection against adverse weather conditions.
Health and Safety is about:
1. Preventing accidents and injuries
2. Ensuring well-being of workers.
3. The physical environment, behaviour of people, competence and safe working
practices.
Influences on Health and Safety:
i. Occupational factors – type of work
ii. Environmental factors – conditions
iii. Human factors – behaviour and attitudes
Job Safety Instructions
Job safety instructions are commonly one of the outcomes of Job Safety Analysis. Such
instructions inform operators of specific risks at different stages of the job and advise him/her
of the precaution to be taken.
Risk Assessment
a. Is a safety tool which ensures that business risks are identified, assessed and control
measures put in place.
b. A technique for preventing accidents and ill-health.
c. It looks at what could go wrong and ways to prevent problems.
 d. A risk assessment provides the basis for enabling actions to be identified and taken to
eliminate hazards or to minimize their effects.
e. Identifying hazards and assessing the risk of the hazard occurring allows us to be
PRO-ACTIVE and not RE-ACTIVE.
Risk Assessment Procedure
i. Identify
ii. Avoid
iii. Measure
iv. Assess
v. Apply controls
vi. Document and Review (assessments should be reviewed from time to time to ensure
that control measures continue to be effective and appropriate. A review should be
made when changes to the workplace occur such as new equipment, etc.)
Hierarchy of Controls
i. Elimination
ii. Substitution
iii. Isolation
iv. Enclosure
v. Local ventilation (then general ventilation)
vi. Good house keeping
vii. Exposure time reduced
viii. Training
ix. PPE
x. Welfare facilities
2.3 Workshop Safety
Workshop safety is planned measures put in place to prevent or minimise accidents to
personnel, visitors and equipment. It should be noted that all tools are dangerous if not used
properly and carefully. You must observe all safety rules and regulations stipulated in the
workshop.
2.4 Basic safety Precautions
• Always listen carefully to the instructor or personnel in the workshop and follow his/her
instructions.
• Never run in the workshop, you could cause an accident.
• Know where the emergency stop buttons are positioned in the workshop.
• Always wear an apron as it will protect your clothes and hold loose clothing such as ties
in place.
• Wear good strong shoes. Training shoes are not suitable.
• When attempting practical work all stools should be put away.
• Always use a guard when working on a machine.
 • Keep hands away from moving/rotating machinery.
• Use hand tools carefully, keeping both hands behind the cutting edge.
• Report any damage you notice on machines/equipment as this could cause an accident.
• Bags should not be brought into a workshop as people can trip over them.
• Before using any machine read all the instructions in the manual and ask questions if
you do not understand.
• Do not use a machine if you have not been shown how to operate it safely.
• Always be patient, never rush work in the workshop.
2.5 Workshop safety Aids
• Include safety colours and visible signs for the purpose of informing personnel without
the use of words
• They draw the attention of personnel and visitors to important safety procedures
• Red symbolises stop or prohibited areas
• Yellow symbolises caution or risk of danger
• Green symbolises a safe working environment
Signs could also be used to:
• indicate a toxic environment (Harmful substances)
• Give or show direction
• First aid kit location
• No smoking
• Laser risk environment
• Fire exit
• Wear safety boots
• No naked light
• Wear ear or eye protection
• Corrosive materials
2.6 Personal Protective Equipment
i. Hand Gloves (Multi-use gloves worn to protect the hands from injuries caused by handling
sharp or jagged objects, wood, or similar hazard-producing materials)
ii. Safety Glasses for eye protection from operations such as
• Chipping, grinding, and impact drilling.
• Welding of any type.
• Riveting, grinding, or burning metals.
iii. Head Protection – Hard hats used when working beneath an operator
iv. Laboratory Coats
v. Hearing Protection - Used in noise areas or hazardous noise producers
vi. Respirators
vii. Foot protection – Boots, Non-skid shoes in slippery environment also to prevent foot or toe
injury from impact and compression forces.
viii. Other equipment used to prevent injury or illness
All are used to increase individual safety while performing potentially hazardous tasks
3.0 Fire in the workshop

Fire occurs when combustible materials or substances react with oxygen to produce heat. Fire
is a chemical reaction that involves rapid oxidation or burning of a fuel. Fuel could be solid,
liquid or gas. Most solids or liquids become vapour or gas before they can burn.
3.1 Classification of Fires
• Class A

– Ordinary combustible or fibrous material like wood, paper, cloth, some

plastics and rubber

• Class B

– Flammable or combustible liquids such as kerosene, paint, thinners, propane

and gasoline or petrol.

• Class C

– Energised electrical equipment such as appliances, panel boxes, power tools

and switches.

• Class D

– Combustible metals such as magnesium, titanium, potassium and sodium.

They burn at very high temperatures and highly reactive to water and other
chemicals.

3.2 How to extinguish various Fires

• Class A(RED) water type

– Principle is to cool the material below its ignition temperature

– Use pressurised water, foam or dry chemical extinguishers

• Class B (CREAM) Chemical foam type for A and B

– Principle is to remove the oxygen and prevent the vapours from reaching
ignition source.
 – Foam, Carbon dioxide, dry chemical and halon extinguishers

• Class C (BLACK) For B and C

– Principle is to use an extinguishing agent that cannot conduct electrical

currents

– Carbon dioxide, ordinary dry chemical and halon fire extinguishers. (Halon is
harmful to environment)

• Class D (BLUE) Dry powder type

– Principle is to absorb the heat from the material and cooling it below its
ignition temperature

– For combustible metals such as Magnesium, Titanium, Potassium, Sodium

– PASS – Pull pin, Aim at base, Squeeze trigger, sweep from side to side

3.3 Moving Cylinders

The majority of accidents involving gas cylinders occur while moving them from one
location to another.
Control measures used to reduce the potential for an accident:
✓ The use of purpose-built trolleys or other suitable devices for gas cylinder
transportation.

✓ Securing the gas cylinder’s valve, disconnecting and removing associated distribution
equipment.

✓ Shutting the cylinder’s valve, disconnecting and removing associated distribution

equipment.

✓ A requirement that only properly trained personnel are permitted to move cylinders.

✓ Use properly designed lifting equipment for the movement of larger gas cylinders.

3.4 Precautions for minor storage and handling of gas cylinders

• Gas cylinders are to be kept away from artificial sources of heat, i. e. radiators, boilers
or steam pipes; and kept clear.
• Gas cylinders should be provided with adequate ventilation at all times.
• Classes of gas cylinders shall be segregated within the store, but need not be
separated.
• Outdoor storage of cylinders shall be separated from other dangerous goods by at
least 3metres. They shall not be less than 1m from any door, window, air vent or duct.
 • All gas cylinders are to be secured in the upright position by chain or other means to
prevent falling.

2.0 Workshop
A workshop is a place where engineering activities such as woodworking and metalworking
operations, vehicle repairs, overhauling and maintenance, fabrication and welding and other
activities that require the use of tools, machinery and equipment are carried out. Therefore, a
workshop is a building located or situated in a conducive environment where engineering
works are carried out. Also, assembling and disassembling of equipment are carried out in the
workshop.
A workshop is a place where tools and equipment are placed and operated to form machines
and its components.

Automobile Workshop

Mechanical Workshop
2.1 Tools Classification
Tools can be classified as:
i. Hand Tools: They are non-energized or non-powered light tools that are moveable
to workpiece or job. Examples: hacksaw, wood saw, screwdriver, plier, chisels, star
drill, punches, hammers, etc. The greatest hazards posed by hand tools are from
misuse and improper maintenance.
Basic safety rules for Hand tools
• Think first i.e. is the tool in good condition?
• Is it the right size for the job? Is it in the proper working condition?
• Hammers should have heads ground properly. Should not have broken claws or handles.
• Cutting tools such as chisels should be kept sharp to ensure good smooth cutting.
Always use proper handles.
• Screwdriver points should not be badly worn and handles should be in good condition.
• Use the proper size and type of screwdriver for the job.

ii. Power Tools: They are Motorised or energized hand tools that are portable.
Examples: Angle grinder,
Basic Safety Rules for Power tools
i. Power tools can be extremely dangerous if not used properly.
ii. Common accidents associated with power tools include minor tears, deep cuts,
amputations, burns from heat, electrocution from naked wires, and broken bones.
iii. Avoid wearing loose clothing or jewellery that could get caught in moving
machinery.
iv. Be alert – watch work while operating
v. Use correct tool for the job
vi. Disconnect power tools before performing maintenance or changing components.
vii. Use correct speed when operating
viii. Keep all guards in place. Cover exposed belts, chains or shafts.
ix. Before clearing jams or blockages on power tools, disconnect from power source.

iii. Machine Tools: They are heavy duty powered tools fixed to the workshop floor. It
could also be on a table where job to be prosecuted are brought to it. Examples:
pillar drill, milling machine, lathe machine, etc. Note that machine tools have
moving parts.
Basic Safety Rules for Machine Tools
• Examine and identify the start and stop buttons
• Wear protective clothing before use
• Ensure machine guards are secured
• Adequate concentration when operating machine
• Switch off if you need to make adjustments and after every operation.
Minimum Requirements in a Workshop
Safe working Conditions and Techniques based on the following:
• Provision of protective clothing

• Un-congested working area (enough working and walking space)

• Proper machine guard for revolving parts

• Safe tool storage area

• Provision of good lighting and ventilation

• Provision of First aid and fire-fighting equipment

• Provision of accessible exit and entry points.

4.0 Classification of Workshop Tools
1. MEASURING TOOL
(a) Steel rule
This is used for measuring distances between two points.

(b) Centre square

This is used for drawing or marking lines across the end of a round bar.

(c) Protractor
This is used for measuring angles between 0o and 180o. It can also be used for checking an
angle.

(d) Metric rule

This is used to take linear measurements between two points. It is calibrated in the metric scale
and can measure in millimeters and centimeters.

(e) Vernier caliper

This is used to measure the external and internal diameters of an object, be it solid or hollow.
It can also be used to measure the internal depth of a hollow object.

Vernier caliper
(f) Calipers
These are used to measure or compare distances or sizes. They consist of two legs riveted
together at the top by a circular spring band and a fine adjustment screw. There are two main

kinds of calipers which are:

(i) Internal caliper: This is used to measure the internal diameter of a pipe.
(ii) External caliper: This is used to measure the eternal diameter of a pipe.

(g) Micrometer screw gauge

This is used to measure the diameter of a spherical solid. It can also be used to measure the
thickness of a hollow pipe.

Micrometer screw gauge

(g) Measuring tape

This is a steel made rule that can be drawn out of its case. This coiled steel can be withdrawn
back to its case after use. It is used to measure object of long dimension.

2. MARKING OUT TOOLS

(a) Surface plate
The surface plate is used for checking the flatness and alignment of a surface. It is also used
for accurately marking out edges.

(b) Scriber
This is used with the aid of a steel rule for marking straight lines on the surface of a metal. It
is made of hardened high carbon steel.

(c) Odd-leg Caliper

This has two legs, one straight and the other curved towards the end. It is used for marking off
scribe lines parallel to an edge, marking centre lines and finding the centre of round bars.

(d) Dividers
This has two straight legs with pointed edges. It is used for marking out circles and semi-circles
and also for setting out distances from steel rule.

(e) Centre/dot punch

This is used for marking small dots on metal where holes are to be made.

(f) Try-square
This is used for checking the squareness of an edge. It is also used for marking out lines which
are at right angles to a given surface.

3. DRIVING TOOLS
(a) Spanners
Spanner is used for tightening or loosening bolts, nuts and studs. They are made from drop
forged steel and coated in chrome to stop corrosion. Higher quality spanners tend to be made
from Chromium-Vanadium alloys. The size of the spanner refers to the size of the nut or bolt
that will fit into the jaws. Some common types of spanners are discussed below:
i. Open-ended Spanners

They are the most popular spanners with an open ended “C” into which nuts and bolts can fit.
They can be either single or double open-ended spanner.

ii. Ring Spanners

They are spanners which hold the nut or bolt with a ring. The recess is generally a six-point or
twelve-point opening for use with nuts or bolts heads with a hexagonal shape. Ring spanners
are often double-ended and usually with offset handles to improve access to the nut or bolt.

Double-ended ring spanners

iii. Combination Spanners
They are spanners that have a ring at one end and are open ended at the other end. Both ends
generally fit the same size of bolt.

Combination spanner
 iv. Adjustable Spanner
The jaw of this spanner can be set to the correct size of the nut or bolt to be worked on through
the worm screw on the spanner.

Adjustable spanners

v. Socket Spanner
It is a hollow cylinder with six-point, eight-point or twelve points recess that fits over one end
of a nut or bolt head. The spanner can be driven either by a handle or built-in universal join

Socket spanner

vi. Box Spanner

A box spanner can also be called either tube spanner or spark plug spanner which is a tube with
six-sided sockets on both ends. The spanner is turned through the insertion of rod through two
holes in the middle of the tube.

(b) Punches
There are three types of punches.
(i) Centre punch
This is used for making small dots in positions where holes are to be made.
(ii) Pin punch
This is used for removing rivets and cotter pins.
(iii) Bell punch
This is an automatic punch that does not require the use of hammer before the dot impression
is made. It can also be used to find the centre of a round bar.
 Centre punch
Pin punch Bell punch

(c) Hammer
Hammers are used for driving in nails into wood pieces that are to be joined together. Hammer
is made of a head, which is made of high carbon steel, and a wooden handle. Hammers are
generally classified according to the type of head. This also differentiates the use of one type
of hammer from another.

Types of hammers
(i) Ball peen head hammer: It is used for general purpose
(ii) Cross peen head hammer: It is used for riveting and for shaping metal.
(iii) Straight peen head hammer: It is used for riveting in awkward positions
(iv) Planishing head hammer: It is used mostly by panel beaters for finishing work
(v) Claw hammer: It has a claw for removing nails.
(vi) Blocking head hammer: It is used for shaping metal on a block or anvil
(vii) Sledge hammer: It is used for breaking concrete and for shaping metals.

Cross peen head Straight peen head Planishing head hammer

Ball peen head hammer Claw hammer
hammer
hammer

Hammer part labelling

Sledge hammer
Blocking head
hammer
(d) Mallet
The head can be made from wood, plastic or rubber. It is used for jobs that required little
pressure and also for driving chisels.

Mallet

(e) Screwdrivers
Screwdrivers are used for driving in and driving out screws for the purpose of joining or
disjoining two different materials together. Different types of screwdrivers exist are:
i. Star screwdriver: It is used for driving in or out screws with slotted heads.
ii. Flat screwdriver: It is used for driving in or out screws with star heads.
iii. Offset screwdriver: It is screwdriver with the blade at right angles to the shaft for use
where a straight screwdriver cannot reach the screw head.
iv. Allen screwdriver: It is used for driving in or out screws with hexagonal or square
heads.

Allen Screwdriver
Star screwdriver Flat screwdriver Off-set screwdriver

(f) Pincers
Pincers are primarily used for removing or pulling nails out of a wood.

4. CUTTING TOOLS
(a) Chisels
There are four different types of chisels.
(i) Flat chisel
This is used for general work in the workshop
(ii) Round nose chisel
This is used for making oil grooves in a shaft or hole.
(iii) Cross-cut chisel
This is used for making keyways and slots in a shaft or a hole.
(iv) Diamond nose chisel
This is used for chiseling inside corners and for cutting V-grooves.

Cross cut chisel Diamond nose

Flat chisel chisel
Round nose chisel

(b) Files
Files are used for removing small amounts of metal from the edge of sheet metal after it has
been cut. The different types of files include the following:

(i) Hand file

It is used for filing flat surfaces.
(ii) Flat file
It does the same job as the hand file; however, it can also file all kinds of flat surfaces.
(iii) Round file
It is used for filing holes and round corners.
(iv) Square file
It is used for filing squares and rectangular holes.
(i) Triangular file
It is used for filing corners in awkward positions.
(ii) Half round file
It is used for the formation of radius.

Square file Triangular file Half round file

Flat file Round file

(c) Scrapers
Scrapers are tools used for removing slight irregularities from flat surfaces and holes after a
piece of metal has been machined to its final shape. The different types of scrapers include the
following:
(i) Flat scraper
It is used for scraping flat surfaces.
(ii) Triangular scraper
It is used for scraping awkward corners where it is impossible to use other scrapers.
(iii) Half round scraper
It is used in round holes of shorter lengths.

Triangular scraper
Flat scraper Half round scraper

(d) Hacksaw
This is used in cutting metal materials other than flat sheets into the required size. Three
types of hacksaw commonly used in cutting operations are junior hacksaw, adjustable
hacksaw and tubular hacksaw

i. Junior hacksaw
Junior hacksaw is used to cut thin sheets and tubes. It is ideal to be used in a tight area because
of its shape.
ii. Adjustable hacksaw
This type of hacksaw can take blades of different length because the frame is adjustable.
iii. Tubular hacksaw
This type of hacksaw can only take one length of blade because of fixed frame. The hacksaw
is more rigid than the adjustable hacksaw.

Tubular hacksaw
Junior hacksaw Adjustable hacksaw

5 WORK HOLDING DEVICES/TOOLS

(a) Bench vice
The vice is fitted by the side of the work bench by means of bolts and nuts. It is usually made
of cast iron and has two jaws, one fixed and the other movable. Work is placed between the
two jaws and held firmly by tightening the movable joint against the fixed joint by means of a
screw mechanism. Operations such as cutting, filing and chiseling can be performed on a
material after it has been held firmly in the bench vice.
(b) Machine vice

This is similar to the bench vice; however, it is used to hold work pieces on machine tools such
as drilling and milling machines.

(c) Hand vice

This vice is used to hold small jobs together that would have been damaged if held on the bench
vice.

(d) G-clamp
The G-clamp is shaped like the letter G. It is used to hold down machineries to the workbench
and for holding pieces of metal together.

(e) F-clamp
The F-clamp is shaped like letter F. It is used for holding work together when gluing or
assembling.

(f) Sash clamp

The sash clamp is used like the G-clamp during assembly. It can however support larger work.

CARE AND SAFETY PRECAUTIONS IN THE USE OF METALWORK HAND

TOOLS
(a) Clean the surface plate and table after use and cover them.
(b) Clean the teeth of files with a brush as soon as they become clogged. Do not use bare
hands.
(c) Do not use a tool without a handle or with damaged handle.
(d) Do not use hammer with a loose head.
(e) Ensure that work is tightly gripped in vice before cutting operation commences.
(f) Stroke the file away from your body while carrying out filing operations.
(g) Do not use chisels with mushroom head and blunt cutting edge.
(h) Keep fingers away from the cutting edge of hacksaw when in use.

3. WORKSHOP MATERIALS VARIOUS GAUGES AND MEASURING DEVICES

➢ Materials Selection Criteria

• Engineering considerations (Strength, durability, hardness, toughness,
malleability, etc)
• Cost
• “Green”?
• Easy commercial availability
• Political (Sanctions on nuclear materials)
• Technology (Cryogenic engines,….)

➢ Materials Selection
• Metals
• Non metals
Choice is mostly a function of cost

Material

Metallic Non - metallic

Ferrous Non – ferrous Natural Synthetic

e.g. cast iron e.g. Aluminium e.g. sand, wood e.g. rubber, glass
Metals
Metals are usually classified into two main groups:
1. Ferrous metals
2. Non-Ferrous metals

Ferrous Metals
Ferrous Metals are metals that contain iron and are affected by magnetism (apart from
stainless steel). Examples of such metals are cast iron, mild steel, high carbon steel, etc

Non-Ferrous Metals
This category of metal does not contain iron and is usually non-magnetic. Examples are
Aluminium, Copper, Brass, Duralumin, Lead, Gold, Silver, etc.
Metals can also be grouped into two categories:
1. Pure metals
They are made up from one chemical element. Copper, iron, tin, lead, gold and silver
are all examples of pure metals which have been mined from the Earth and extracted
from the ore using a process called smelting.

2. Alloys
An alloy is a mixture of pure metals or a metal with a substance such as carbon added.
Examples of alloys are: steel (iron and carbon), Duralumin (Aluminium and Copper),
Brass (Copper and Zinc) and Bronze (Copper and Tin).
Alloying
Metals are alloyed to improve the qualities of the individual pure metals e.g. both
copper and tin as pure metals are both soft metals that are easily bent and scratched.
When alloyed together (90% copper plus 10% tin) they produce bronze which is hard,
rigid and resists scratching. Bronze is used for our copper coins.
Alloying
Metals are alloyed to improve the qualities of the individual pure metals e.g. both
copper and tin as pure metals are both soft metals that are easily bent and scratched.
When alloyed together (90% copper plus 10% tin) they produce bronze which is hard,
rigid and resists scratching. Bronze is used for our copper coins.
Corrosion
When choosing metals, resistance to corrosion must be an important factor. Corrosion
is caused by oxygen in the air combining with the atoms of metal, at the surface of the
metal, to create a new chemical called oxide e.g. iron oxide is called rust.
In steel, the rust layer is loose and can fall away, this exposes new atoms that will
combine with oxygen to form new rust.
In non-ferrous metals, the oxide layer is dense and does not fall away, this creates a
barrier to the oxygen in the air and new corrosion occurs very slowly. The layer is called
tarnish.
Properties
Both physical and mechanical properties vary greatly between different metals and alloys and
are an important part of the selection process.

Non metals
The non-metals are classified as:
1. Wood
2. Soil
3. Synthetics
4. Plastic
Forms of Metals
Metals for commercial purpose exist in different shapes and forms. The available forms are:
(a) Tube form e.g. hollow cylinder shapes.
(b) Channel form e.g. solid I, H and T shapes.
(c) Strip form e.g. wire mesh, wire gauze.
(d) Wire form e.g. electric cables.
(e) Plate form e.g. flat rectangular or square sheets.
(f) Rod form e.g. solid cylindrical shapes.
(g) Sheet form
(h) Bar form
The following cross sections are typical examples of how metals are supplied to the school
workshop.

Forms of Metal
➢ Metal Properties
(a) Electrical Properties
1. Density: Is the amount of matter (mass) in a material.
Density Material
High Gold, Lead
Medium Copper, steel
Low Wood, plastics
2. Thermal Conductivity: Is how fast heat can travel through a material. If a material is
known as an insulating material, heat travels very slowly through it.
Thermal Conductivity Material
High Copper, Aluminium
Medium Mild steel, tin
Low Wood, polystyrene

3. Electrical Conductivity: Is how fast electricity can travel through a material. A poor
conductor is an insulator.
Electrical Conductivity Material
High Copper, Aluminium
Medium Mild steel, tin
Low Wood, polystyrene

4. Fusibility: Is the measure of how easy it is to melt a material. A highly fusible

material has a low melting point.
Fusibility Material
High Tungsten, chromium
Medium Mild steel, tin
Low Wood, polystyrene

5. Thermal Expansion: Is the amount of expansion that occurs when the material is
heated. A high expansion material will become noticeably larger when heated.
Thermal Expansion Material
High Polythene, Nylon
Medium Aluminium, tin
Low Wood, Titanium

(b) Mechanical Properties

1. Strength: Is the measure of how well a material can withstand force without
permanently breaking. There are different types of strength measurements.
• Tensile Strength: Is the ability to resist stretching by the pull of forces and
is an essential strength for cables, chains and ropes.
• Compressive Strength: Is an ability to withstands pushing forces which try
to crush or shorten.
• Bending Strength: It is an ability to withstand forces attempting to bend.
• Shear Strength: Is an ability to resist strong sliding forces in opposite
directions.
• Torsional Strength: It withstands twisting forces under torsion (torque)
2. Malleability: Is the measure of how easily a material can be permanently
deformed by compressive forces e.g. hammering without cracking.
 Malleability Material
High Copper, Aluminium
Medium Mild steel, bronze
Low Wood, thermoset plastic

3. Ductility: Is the measure of how easily a material can be permanently deformed,

without breaking, by bending, stretching or twisting.
Ductility Material
High Polypropylene, copper
Medium Mild steel, bronze
Low Wood, thermoplastics

4. Hardness: Is the measure of how well a material resist scratching and being worn
away by other materials.
Hardness Material
High Diamond, chromium
Medium Mild steel, bronze
Low Wood, Thermoplastics

5. Toughness: Is the measure of how well a material can stand up to sudden forces
e.g. a hammer blow without cracking.
Toughness Material
High Polycarbonate, copper
Medium Mild steel, brass
Low Glass, polyester resin

6. Brittleness: Is the opposite of tough. Brittle materials cannot withstand sudden

impact.
7. Durability: Is the measure of how well a material stands up to weathering (the sun,
cold, wind, rain, corrosion and rotting).
Durability Material
High Gold, tin
Medium Ceramics, bronze
Low Mild steel, softwoods

METAL JOINING PROCESSES

Metal Joining is defined as joining of two metal parts either temporarily or permanently with
or without the application of heat or pressure.

Classification of metal joining processes

• Permanent Joining Riveting, Welding, Brazing, Soldering –
•Semi-permanent: Adhesive Bonding
•Temporary Joining: Bolting
•Mechanical Assembly
a) Bolt and screw non-permanent
b) Riveting permanent
c) Clamping non-permanent

1. Riveting
Riveting is the process of joining two or more pieces of metal together permanently. The
process uses metal plugs, more commonly known as rivets.
To form the joint, the shank of the rivet is passed through a previously drilled hole in the
components to be joined, it is then cut to size and spread or shaped, thus preventing the parts
from separating.
Rivets are classified by the shape of the head, their diameter and length. Common rivet head
are round (or snap), countersunk, pan and flat. Other types of rivets found in the workshop are
bifurcated and pop rivets. In general, the type of work at hand will determine the type of rivet
to use.
Rivets are made in most types of metal such as mild steel, copper, stainless steel, brass,
aluminium. When using a rivet, always ensure that the rivet being used is the same material as
the metals being joined or it will result in aggravated corrosion at the rivet site.

2. Brazing
➢ Brazing is metal joining process in which the filler metal or alloy is heated to a
temperature above 450oC and melted only filler metal. The filler metal melts and
deposits fusing the workpiece.
➢ Workpiece does not melt.
➢ Base metal is heated and filler metal is distributed between two close fitting parts
by capillary action Torch/Dip/Furnace/Induction/Salt-bath Brazing.
➢ Filler metals: Aluminium-silicon; copper; brass; copper-silver; nickel alloy; etc

3. Soldering
Soldering is metal joining process in which the filler metal or alloy is heated to a temperature
below 450oC and melted only filler metal. The filler metal melts and deposits fusing the
workpiece.
• Soldering solder is an alloy of Tin (63%) & Lead (37%) 60/40 solder melts at 361F.
• Extensively used in electronics and jewelry industry.

4. Welding
• Welding is a process of permanently joining materials. Welding joins different
metals/alloys with a number of processes, in which heat is supplied either electrically
 or by means of a torch. Welding is done by application of heat or both heat and pressure.
The most essential requirement is heat.
• Pressure may be employed, but this is not in many processes essential.
• The welding process evolves applying heat to the workpiece.
• The heat applied should be such that the workpiece should melt, i.e. the temperature at
which welding is done, should be more than the melting point of the workpiece to be
welded.

Classification of Welding Processes

✓ Gas welding
✓ Arc welding
✓ Resistance welding
✓ Solid state welding
✓ Thermo-chemical welding
✓ Radiant-Energy welding

Welding Processes Air

✓ Acetylene Oxy-Acetylene
✓ Oxy-Hydrogen Pressure gas
Basic Requirements of Welding Processes

1. The Two Metal (work pieces) should be either in contact with each other or closely placed
(concept of root gap).
2. The weld surfaces should be free from oxides, paint, oil, dirt, grease etc.
3. Energy Source, Electrode and Filler Metal rod/ wire.
4. Shielding: During Welding if the metal is exposed to air directly the Oxygen in air reacts
with the metal to form oxide which results in poor welding. In order to avoid the shielding
gas is used.

Gas Welding
Gas Welding is a fusion welding process. It joins metals, using the heat of combustion of
oxygen/air and fuel gas mixture. The intense heat thus produced melts and fuses together the
edges of the parts to be welded, generally with the addition of a filler metal.

Application of Gas Welding

i. For joining thin metals.
ii. For joining materials in whose case excessively high temp. or rapid heating and cooling of
the job would produce unwanted or harmful changes in the metal
iii. For joining most ferrous and non-ferrous metals, i.e. Al, Cu, Ni, Mg, and its alloys etc.

Arc Welding
Arc Welding is a group of welding processes, wherein fusion is produced by heating with an
electric arc or arcs, mostly without the application of pressure and with or without the use of
filler metal depending upon the base plate thickness. Resistance Welding Resistance welding
is a group of welding processes where in fusion is produced by the heat obtained from flow of
electric current in a circuit of which the work is a part and by application of pressure. Pressure
creates friction and the heat thus produced leads to fusion. No filler metal is used.

Materials, Types of Joints, Processing of Timber

• Of all the different construction materials, wood is probably the most often used and
perhaps the most important.
• The variety of uses of wood is practically unlimited.
LUMBER
The terms "wood" "lumber," and "timber" are often spoken of or written in ways to suggest
that their meanings are alike or nearly so. But in the Builder’s language, the terms have
distinct, separate meanings.
• Wood is the hard, fibrous substance that forms the major part of the trunk and
branches of a tree.
• Lumber is wood that has been cut and surfaced for use in construction work.
• Timber is lumber that is 5 inches or more in both thickness and width.
SEASONING OF LUMBER
Seasoning of lumber is the result of removing moisture from the small and large cells of
wood— drying.
The advantages of seasoning lumber are to
• reduce its weight;
• increase its strength and resistance to decay; and
 • decrease shrinkage, which tends to avoid checking and warping after lumber is
placed.

Methods of Seasoning
A seldom used and rather slow method of seasoning lumber is air-drying in a shed or stacking
in the open until dry.
A faster method, known as kiln drying, has lumber placed in a large oven or kiln and dried
with heat, supplied by gas- or oil-fired burners.
Lumber is considered dry enough for most uses when its moisture content has been reduced
to about 12 or 15 percent.
As a Builder, you will learn to judge the dryness of lumber by its color, weight, smell, and
feel. Also, after the lumber is cut, you will be able to judge the moisture content by looking at
the shavings and chips.

Defects and Blemishes

✓ A defect in lumber is any flaw that tends to affect
• the strength,
• durability, or
• utility value of the lumber.
✓ A blemish is a flaw that mars only the appearance of lumber.
✓ However, a blemish that affects the utility value of lumber is also considered to be a
defect; for example, a tight knot that mars the appearance of lumber intended for fine
cabinet work.
Simple Machines for Postharvest Processing
Some of the most common functions by which food processing equipment are grouped are:
i. Preparation
ii. Mechanical processing
iii. Heat processing
iv. Presentation
v. Packaging

Preparation
Some of the unit operations which manufacturers employ during the raw material preparation
stage include cleaning, sorting, grading, or peeling (or skinning). Table 1 below describes
some of the preparatory unit operations and outlines the equipment used to execute them.
Table 1: Food Preparation Equipment by Unit Operation
Unit Operation Description Equipment Employed
Cleaning Remove foreign matter and Wet Processes
contaminants – e.g. soil, oil, • Soak/floatation tanks
insects, skins, chemicals, etc. from (soaking)
the surface of raw food material via • Spray washers (spray
wet and dry cleaning processes washing)
• Washing systems (washing)
• Sterilizers (sterilizing)
• Ultrasonic cleaners
Dry Processes
• Air classifiers
• Magnetic separators
• Screening separators
Grading • Closely related to and often • Tungsten lights (candling)
precluding sorting processes • Image processors
• Assesses several • Laboratory equipment
characteristics of food
matter (e.g. flavor, damage,
skin color, aroma, etc) to
determine the overall
quality.
Size Reduction Reduces the average particle size of Grinding/Crushing
solid food matter through • Impact mills
mechanical processes involving • Pressure mills
compression, shear, or impact
• Attrition mills
force.
 • Jaw crushers
• Roll Crushers
• Strainers/pulpers

Cutting/Chopping
• Knives/blades
• Band saws
• Slicing machines
• Meat grinders

Size Enlargement Increases the average particle size Extrusion

of solid food matter through • Non-thermal extruders
mechanical processes, such as • Single-screw extruders
extrusion, agglomeration, or
• Twin-screw extruders
forming
• Refrigerated extruders

Agglomeration
• Rotating pans
• Rotating drums
• High-speed agitators
• Tableting equipment
• Pelletizing equipment

Forming
• Bread molders
• Pie and biscuit formers
• Confectionary molders
• Enrobing machines

Homogenization • Also referred to as • Homogenizers

emulsification • Emulsifiers
• Reduces the average • Colloid mills
particle size and increases • High shear mixers
the consistency of semi-
solid and liquid food matter.
Mixing • Also referred to as blending Fluid Mixers
• Combines and disperses two • Agitated tanks
or more components into • Paddle mixers
one another to achieve and • Anchor mixers
maintain a uniform mixture • Turbine mixers
and / or an alteration to the Dough/Paste Mixers
functional or aesthetic • Horizontal dough mixers
qualities of the food product • Sigma-blade mixers
(e.g. texture) • Cutter mixers
• Type of equipment depends Solid Mixers
on gas/liquid, liquid/liquid, • Diffusive (passive) mixers
liquid/solid, solid/solid
• Convective (active) mixers
• Drum blenders
 Dept: ABE
Course Title: WORKSHOP PRACTICE (2 Units)

Course Code: ABE 204

Course Lecturer(s): Dr. Ola O. I.
Dr. Adeosun O. J.
Engr. Adepoju V. O.

1
 Course Work
 Workshop safety measures.
 Introduction to Workshop hand and powered tools emphasizing safety
measures to be taken during operation.
Workshop materials various gauges and measuring devices.
General description of the function and capabilities of grinding
machine, drilling machine, lathe machines, milling machines, shaping
machines and cutting machines.
 Practice in the use of machines.
 Welding bracing soldering and riveting.
Carpentry: hand tools, materials, types of joints, processing of timber.
 Manufacture of simple components using steel and wood.

2
MATERIALS SELECTION CRITERIA
• Engineering considerations( Strength, durability..)
• Cost
• “Green”?
• Easy commercial availability
• Political(Sanctions on nuclear materials)
• Technology(Cryogenicengines,….)
Materials
Metals are usually classified into two main groups; FERROUS metals and NON FERROUS
metals.
 Ferrous Metals
These metals contain iron and are affected by magnetism (apart from stainless steel);
examples of such are Cast Iron, Mild Steel, High Carbon Steel, etc.
 Non-Ferrous Metals
As the name implies (NON), this category of metal does not contain iron and is usually non magnetic;
examples are, Aluminium, Copper, Brass, Duralumin, Lead, Gold, Silver, etc.

Metals can also be grouped into two categories:

 Pure Metals
Pure metals are made up from only one chemical element. Copper, iron, tin, lead, gold and
silver are all examples of pure metals which have been mined from the Earth and extracted
from the ore using a process called smelting.
 Alloys
An ALLOY is a mixture of pure metals or a metal with a substance such as carbon added;
examples of alloys are:- Steel (Iron & Carbon), Duralumin (Aluminium & Copper), Brass
(Copper & Zinc) & Bronze (Copper & Tin).
Alloying
Metals are alloyed to improve the qualities of the individual pure metals e.g. both
copper and
tin as pure metals are both soft metals that are easily bent and scratched. When
alloyed
together (90% copper plus 10% tin) they produce bronze which is hard, rigid and
resists
scratching. Bronze is used for our ‘copper’ coins.
Corrosion
When choosing metals, resistance to corrosion must be an important factor.
Corrosion is caused by oxygen in the air combining with the atoms of metal, at the
surface of
the metal, to create a new chemical called oxide, e.g. iron oxide is called rust.
In steel, the rust layer is loose and can fall away; this exposes new atoms that will
combine
with oxygen to form new rust.
In non ferrous
Metals of the oxide layer is dense and does not fall away; this creates a barrier
to the oxygen in the air and new corrosion occurs very slowly. The layer is called
 Metal Joining Processes: Welding, Riveting,
Bolting, Brazing, Soldering
• Metal Joining is defined as joining of two metal parts either temporarily
or permanently with or with out the application of heat or pressure.
 Classification:
• Permanent Joining: Riveting, Welding, Brazing, Soldering –
• Semi-permanent: Adhesive Bonding
• Temporary Joining: Bolting
 Mechanical Assembly
A) Bolt & Screw Non-permanent
B) Riveting Permanent
C) Clamping Non-permanent
Riveting
• Its is metal joining Process in which the two metallic parts are
joined by the use of rivets.
• In this process, the metallic parts to be joined do not undergo
any change in their physical structure or atomic structure.
• However Force is required for riveting
• Riveting is used widely in automobile and aerospace industry
and in many other applications where we require permanent/
semi-permanent bonding and where bolting and welding is not
an option.
• Mostly done for low thickness sheet metals and Aluminium
 Bolt/Screw (and/or nut).
• In this metal joining process, the metallic parts are joined together by
means of Bolt/Screw (and/or nut). This Process is widely used in
assembling of parts are to be joined temporarily or joints which require
periodic maintenance.
• Two main types of loads on bolted joints: Tension and Shear Bolting
• Bolted Joints ‐ Details Screw Joint, Bolted Joint, Stud Joint, Nut
Washer Bolt, Head Thread Shank Washer Nut Bolt
• Common types of Washers, Common types of Nuts, Common types of
Bolt Heads q Components of a Bolted Joints 1. Bolt 2. Washer 3.
(and/or) Nut q Different combinations of the above may be used for a
joint depending on the load
 Welding
• Welding is a process of permanently joining materials. Welding
joins different metals/alloys with a number of processes, in which
heat is supplied either electrically or by means of a torch. Welding
is done by application of heat or both heat and pressure. The most
essential requirements is Heat. Pressure may be employed, but this
is not in many processes essential. The welding process evolves
applying heat to the work piece. The heat applied should be such
that the work piece should melt, i.e. the temperature at which
welding is done, should be more than the melting point of the work
piece to be welded.
Classification of Welding Processes
Classification of Welding Processes
• Gas Welding
• Arc Welding
• Resistance Welding
• Solid State Welding
• Thermo-chemical Welding
• Radiant- Energy Welding

Welding Processes Air –

• Acetylene Oxy- Acetylene
• Oxy- Hydrogen Pressure gas
Basic Requirements of Welding Processes
1. The Two Metal (work pieces) should be either in contact with
each other or closely placed (concept of root gap).
2. The weld surfaces should be free from oxides, paint, oil, dirt,
grease etc.
3. Energy Source, Electrode and Filler Metal rod/ wire.
4. Shielding: During Welding if the metal is exposed to air
directly the Oxygen in air reacts with the metal to form oxide
which results in poor welding. In order to avoid the shielding gas
is used.
Gas Welding
• Gas Welding is a fusion welding process. It joins metals, using
the heat of combustion of oxygen/air and fuel gas mixture. The
intense heat thus produced melts and fuses together the edges of
the parts to be welded, generally with the addition of a filler metal.
• Application of Gas Welding
i. For joining thin metals.
ii. For joining materials in whose case excessively high temp. or
rapid heating and cooling of the job would produce unwanted or
harmful changes in the metal
iii. For joining most ferrous and non-ferrous metals, i.e. Al, Cu, Ni,
Mg, and its alloys etc.
Arc Welding
• Arc Welding is a group of welding processes, wherein fusion is
produced by heating with an electric arc or arcs, mostly
without the application of pressure and with or without the use
of filler metal depending upon the base plate thickness.
Resistance Welding Resistance welding is a group of welding
processes where in fusion is produced by the heat obtained
from flow of electric current in a circuit of which the work is a
part and by application of pressure. Pressure creates friction
and the heat thus produced leads to fusion. No filler metal is
used.
Brazing
• Brazing is metal joining Process in which the filler metal or
alloy is heated to a temperature above 450OC and melted Only
filler metal melts and deposits fusing the workpiece.
• Workpiece doesn’t melts.
• Base Metal is heated and filler metal is distributed between two
close fitting parts by capillary action Torch/ Dip/ Furnace/
Induction/ Salt-bath Brazing
• Filler metals: Aluminium- Silicon; Copper; Brass; Copper-Silver;
Nickel alloy, etc
BRAZING MERIT AND DEMERIT MERIT
• MERIT
Dissimilar metals which can not be welded can be joined by brazing.
 Very thin metals can be joined.
Metals with different thickness can be joined easily.
In brazing thermal stresses are not produced in the work piece. Hence
there is no distortion. Using this process, carbides tips are brazed on the
steel tool holders.
Very Quick process
• DEMERIT
Brazed joints have lesser strength compared to welding.
 Joint preparation cost is more. Can be used for thin sheet metal sections.
Soldering
• Soldering is metal joining Process in which the filler metal or
alloy is heated to a temperature below 450OC and melted Only
filler metal melts and deposits fusing the workpiece. Soldering
Solder is an alloy of Tin (63%) & Lead (37%) 60/40 Solder
melts at 361 F Extensively used in electronics and jewelry
industry
 materials, types of joints, processing of timber.
 Of all the different construction materials, wood is probably the most often used and perhaps the most important.
The variety of uses of wood is practically unlimited.
LUMBER
The terms "wood" "lumber," and "timber" are often spoken of or written in ways to suggest that their meanings are alike or nearly
so. But in the Builder’s language, the terms have distinct, separate meanings.
• Wood is the hard, fibrous substance that forms the major part of the trunk and branches of a tree.
• Lumber is wood that has been cut and surfaced for use in construction work.
• Timber is lumber that is 5 inches or more in both thickness and width.

SEASONING OF LUMBER
Seasoning of lumber is the result of removing moisture from the small and large cells of wood— drying.
The advantages of seasoning lumber are to
• reduce its weight;
• increase its strength and resistance to decay; and
• decrease shrinkage, which tends to avoid checking and warping after lumber is placed.

METHODS OF SEASONING
A seldom used and rather slow method of seasoning lumber is air-drying in a shed or stacking in the open until dry.
A faster method, known as kiln drying, has lumber placed in a large oven or kiln and dried with heat, supplied by gas-
or oil-fired burners.
Lumber is considered dry enough for most uses when its moisture content has been reduced to about 12 or 15
percent.
As a Builder, you will learn to judge the dryness of lumber by its color, weight, smell, and feel. Also, after the
lumber is cut, you will be able to judge the moisture content by looking at the shavings and chips.
DEFECTS AND BLEMISHES
 A defect in lumber is any flaw that tends to affect
• the strength,
• durability, or
• utility value of the lumber.
 A blemish is a flaw that mars only the appearance of lumber.
 However, a blemish that affects the utility value of lumber is also considered to be a defect; for example, a tight
knot that mars the appearance of lumber intended for fine cabinet work.
CLASSIFICATION OF LUMBER
Trees are classified as either softwood or hardwood . Therefore, all lumber is referred to as either “softwood” or
“hardwood.” The terms “softwood” and “hardwood” can be confusing since some softwood lumber is harder than
some hardwood lumber. Generally, however, hardwoods are more dense and harder than softwoods.
LAMINATED LUMBER
Laminated lumber (figure 3-29) is made of several pieces of lumber held together as a
single unit, a process called lamination. Usually 1 1/2-inches thick, the pieces are
nailed, bolted, or glued together with the grain of all pieces running parallel.
Laminating greatly increases the load-carrying capacity and rigidity of the wood.
PLYWOOD
Plywood is constructed number of layers (plies) of by gluing together a wood with the
grain direction turned at right angles in each successive layer. This design feature
makes plywood highly resistant to splitting.
JOINTS AND JOINING
One basic skill of woodworking is the art of joining pieces of wood to form tight, strong,
well-made joints. The two pieces that are to be joined together are called members.
The two major steps in making joints are (1) laying out the joint on the ends, edges, or
faces and (2) cutting the members to the required shapes for joining.
Figure 3-42.-End butt joints with fishplates.
33