GE 102
Manufacturing Technology
Workshop Technology
W. A. Chapman
Workshop Processes and
Materials
Bruce J. Black
Materials and Processes in
Manufacturing
E. Paul DeGarmo
TABLE OF CONTENTS
Chapter Title
Page
Chapter 1
Health and Safety
1
Chapter 2
Engineering Materials
11
Chapter 3
Casting Processes
27
Chapter 4
Sheet-Metal Operations
43
Chapter 5
Measuring Equipment's
53
Chapter 6
Machining Processes
71
Chapter 7
Plastic Forming Processes 103
Chapter 8
Joining of Metals
117
Chapter 9
Carpentry
133
3
Workshop Training
Workshop
Title
1
Turning
2
Welding
3
Casting
4
Sheet-Metal
5
Carpentry
Engineering Materials
2-1 Introduction
Engineering materials are those the engineer uses in his
work. Nearly all materials existing on and under the ground
are used in engineering. Some of these materials are used
directly as water, sand, etc., others need more or less
treatment as iron ore, petroleum. Moreover, some materials
are used alone in industry as wood, leather, etc., others are
mixed together to produce other materials having specific
properties as adding chromium to steel to improve its
corrosion resistance.
2.3. Properties of Materials
2.3.1 Classification of properties
a) Physical properties: As the shape, dimensions, porosity, etc.
b) Chemical properties: As the chemical composition, acidity, etc.
c) Thermal properties: As the expansion, thermal conductivity,
specific heat, etc.
d) Electrical and Magnetic properties: As the electrical resistivity
and conductivity, magnetic permeability, etc.
e) Optical properties: As the color, light reflection and absorption etc.
f) Acoustical properties: As the acoustic reflection and absorption, etc.
g) Mechanical properties: They are the properties, which determine
the behavior of the material under loads.
2.3.2 Main Mechanical properties of Materials
1-Elasticity:
Is the ability of the material to restore its original shape or volume at once
when the load is released.
2- Plasticity:
Is the ability of the material to change its shape and dimensions under load
and to keep the new shape and dimensions after the load is released.
3- Ductility:
Is the ability of the material to deform (elongate) in static tension without
failure.
4- Malleability:
Is the ability of the material to change its shape under pressure
(compressive load) without failure.
5- Brittleness:
Is the ability of the material to fail without a noticeable in its dimensions.
6- Hardness:
Is the resistance of the material to penetration of another harder body?
7- Stiffness:
Is the resistance of the material to any change of shape, it is measured
by Young’s modulus.
8-Strength:
Is the measure of the ability of materials to resist stresses (tensile,
compressive, bending, shearing or torsion) under different conditions of
loading (static and dynamic) and different temperatures. It is measured
by the stress units  ( = force/area)
9- Toughness:
Is the ability of the material to resist the dynamic load (i.e., to resist
shocks)
2.4 Main Mechanical Tests of Metals
2.4.1 Tensile Test
Tensile test is of a static type, it is the easiest mechanical test to
perform. It is carried out to determine the strength and plasticity
of materials. Moreover, the result of the tensile test gives a clear
idea about the other mechanical properties of the material under
test, mainly its ductility.
For the tensile test to be carried out, we use a test specimen and a
tensile test machine.
Test specimen: It is either round or flat shape cross-section. It ha s
a standard shape and dimensions to be able to compare the
obtained results. Fig 2.1 shows test specimens. The mechanical
properties in tensions are determined on the gauge length lo of the
specimen.
Fig. 2.1 Tensile test specimens
A tensile test machine
Fig. 2.3 a tensile test diagram for mild steel
The elastic load Pe:
Is the maximum load that causes elastic deformation only, i.e.,
deformation that disappears when the load is removed. The corresponding
stress is the elastic limit e
e = Po/Fo
Pa or MPa.
where Fo: Initial cross-sectional area of the specimen
Here is a line relation in the region of elastic deformation between stress
and strain for metals and alloys. It confirms to the low of proportionality
(Hook’s low):
=E.
Pa or MPa .
E = / = tan 
Where  (strain) = l/lo
= (l1-lo)/lo
The coefficient of proportionality E, called the nodules of elasticity or
Young’s modulus, characterizes the rigidity of a material, i.e., its resistance
to elastic deformation in tension.
Examples:
1- When testing a steel specimen of diameter D=10 mm.,
the maximum load Pu is 28400 N. Calculate the ultimate
strength u.
Solution:
Fo = D2/4 = .102/4 = 78.5 mm2 = 78.5 x 10-6 m2
u = Pu/Fo = 28400/78.5 x 10-6 = 361.8 MPa.
2- Determine the elongation  of steel, if the specimen
gauge lengths before and after teat lo and l1 are: 50 and 58
mm. respectively.
Solution:
 = (l1 – lo)/lo x 100 = (58-50)/50 x 100 = 16%
2.4.2Hardness Test
Hardness test is of a static type. It has found
extensive applications in all branches of industry
due to its rapidity, simplicity and its nondestructive character.
Because the hardness of the metal is its resistance
to penetration to another harder body, thus
hardness test is applied by pressing a body in the
metal under test, then evaluating its influence.
There exist several hardness testing methods
having the same principles but differ in the shape
of the penetrating body. A brief idea about those
most widely used is given in table 2.1
Method
Brinell
Symbol Penetrating Parameter of
hardness
body
evaluation
HB
Steel ball Applied force
and area of
indentation
Rockwell
HRB
HRC
Steel ball or
Conicalshaped
diamond
Difference in
depth of
indentation made
by additional and
preliminary loads*
Vickers
HV
Squarebased
diamond
pyramid
Applied force
and mean
value of
diagonals’
lengths
2.4.3 Impact Test
Impact test is of a dynamic type. It indicates the
resistance of metals to fracture when it is
subjected to impacts. Fig 2.4 shows a pendulum
type impact machine.
The notched specimen is placed on its support so
that the blow of the striker will be opposite to
the notch. The pendulum of weight G is raised to
a constant height h1 from where it is released to
fracture the specimen and rises again to the
height h2.
The work done to fracture the specimen
is:
A= G (h1 – h2) joule.
The heights of the pendulum before and
after the blow are expressed by the angles
through which it is raised. Thus
A= G.l (cos1 - cos2) joule.
The angle 1 is constant, while the angle
of swing of the pendulum after fracturing
the specimen 2 is measured on a circular
scale on the machine. The resistance of
metal to impact is given by:
ak = G(h1 – h2)/Fo = G.l/Fo (cos1 - cos2)
joule/m2
Where Fo… is the cross-sectional area in
m2 of the specimen at the place of
fracture.
2.4.4 Fatigue Test.
The failure of a metal under repeated reversing
stresses is called fatigue. The resistance of a metal
to fatigue failure is characterized by its fatigue
limit, which is the maximum stress the specimen
can withstand without failure when this stress is
repeated for a specified number of cycles (5x106
cycles for steels and 20x106 cycles for non-ferrous
metals).
The fatigue limit is usually determined by subjecting rotating
specimen to repeated reversing stresses. At least six
specimens must be tested to determine the fatigue limit. The
first specimen is tested at a stress 1 and the number of
cycles N1 at which failure is determined. The stresses 2, 3
etc., for the second and subsequent specimens are increased
or reduced, depending on the number of cycles which caused
the failure of the first specimen. The corresponding number
of cycles N2, N3, etc., at which failure of such specimens
occurs are determined too. The obtained results are plotted
on a diagram Fig. 2.5. The horizontal section is a straight line
and it is the maximum stress at which failure will not take
place after an infinite number of loading cycles.