INTRODUCTION
Product is an article obtained by transformation of raw material.It fulfill some identified needs
and is marketed /sold by the manufacture to eran profit .Hence product is a salable item
manufactured in with out compromising for qulity and reliadility.
The manufacturing processes help in shaping product with ease at competitive cost.Aproduct
can be visualized by a simple input-output model as shown below.
Diag.1
The material out which the product is made is known as raw materialand the specific technique
used in shape it is known as manufacturing process.Some identified machines and tools are
required to shape the product with required dimensional accuracies and finish.
The proficiency of individual person in selection of manufacturing process,raw material for
product,machines and tools to shape and skill to work on material to shape it matters for a
useable product.
A product may have single component or may be an assembly of number of components,
Services are also been now covered under the definition of product.
To be a successful engineer, one has not only know the language of process technologist , but
also to practical them, so as to aquire the reasonable knowledge and skill.
The manufacturing process can be divided in some of the following groups:
1.
2.
3.
4.
Casting
Mechanical working of metals (plastic deformation and metal forming)
Fabrication
Metal machining
The raw material used in manufacturing may be metallic and non-metallic, Casting is a
process of making metallic items by pouring molten metal in a mould cavity and
allowing it cool down. The some of the items made by this process are base and body of
machines, Castiron,alluminium , copper base alloys can easily be shaped by the casting
process.
Mechanical working of the metal is an intentional plasticdeformation of metal , to bring
it in desired shape and size under the action of externally applied force . the
deformation can be possible at room temperature or elevated temperature. At higher
temperature the deformation is quicker and more prominent . Forging is one of the
processes of plastic deformation . When work is done using hand tools, the process is
known as smith, Chisels,Screw driver, Hammers are some of the items made by smithy
or forgong. Except brittle material mechanical working of metals can be used to handle
all metals.
Fabrication includes cutting, shaping and joining standard section so as to form
structure, Bicycle frame, motor cycle chassis, ships etc. are fabricated items. In most of the
cased, for joining welding is preferred on account of strong leak proof joint can be made with
convenience at low cost.
Welding can be defined as the process of joining two metal pieces by heating them to the
required welding temperatures, with or without the application of pressure , or use of
additional filler materials.
Metal machining is a processof shaping material by removing unwanted extra material from the
work in the form of small chips. High dimensional accuracles and finishes are the requirement
of the product made by assembling two or more components. Such as motor cycle and car
engine, electric motors generator etc. Most of the work is done on machine tools and little
work by fitting techniques
The properties of metals and alloy are considerable improved by controlled heating and
coolong of metal in solid state. The process of achieving required properties by heatng and
cooling is known as heat treatment, Annealing normalization , hardening etc. are some of the
methods of the heat treatment.
IIn powder metallurgy componanats are made by metal powder ,On account of high hardness,
it is difficult to manufacturing of carbide tool tips or tungsten electrical contacts points. The
task is completed by powder metallurgy of powder metallurgy includes making of material
powder,pressing powder ,in metallic dies at a very high pressure to get the required shape and
strengthening by baking it in a oven maintaining inert atmosphere.
Process technologies are backbone for emerging technologies. The achievements of electronics,
computer technology, informationtechnology, instrumentation,civil engineering etc. totally
based on low cost reliable supporting hardware. Low cost computer is biggest achievement of
process technologies is having wide applicationin all the fields.
The unlimited capabilities of computer are resulting in simplifying all aspects of product
manufacturing .For low cost automation machines are now equipped with industrial computer .
The complicity in manufacturing is considerably reduced by computer hardware and software.
Diagram 2
Properties of material
Selection of material is done based on thierial properties justifying their suitability for the work
These properties can be grouped as:
1.
2.
3.
4.
5.
6.
7.
Physical properties
Chemical properties
Electrical properties
Magnetic properties
Thermal properties
Opticaal properties
Mechanical properties or Manufacturing properties
Physical properties
Physical properties are mainly concern with density, porosity, appearance i.e. shape,size
and colour etc. They are independent of external force.
Chemical properties
Engineering materials suffer from chemical deterioration when they come in contact
with other substance. Such as corrosion ressistance are considered better.The important
chemical properties are:
1. Corrosion resistance
2. Chemical composition
3. Acidity or Alkalinity
Chemical properties mainly concern to the structure and composition of a material.
Electrical properties
Thest propertiesof material are of prime importance for electrical equipments such as
electric conductivity, resistivity , di-electric strength etc.
Conductivity is the property of the material owing to which the electric current flows
easily through the material. The material having resistance for flow of electricity.
Magnetic properties
These properties are mainly concern to workability of material to shape and
performance of material under various loading conditions. They include the elastic and plastic
behavior of the material .
Important mechanical properties are strength , modulus of elasticity elastic limit,
endurance limit, ultimate strength, hardness, brittleness, creep , yield stress, malleability,
ducktility, toughnes etc.
Mechanical properties of the materials can be determined by loading material under
tension, compression, shear, bending, impact etc.
Strength
Safe load carrying capacity of a material is known as strength of material measured in
Kg/cm2 Corresponding to nature of load strength may be tensile, compressive and shear .
Universal tensile testing machne , compression testing machine and teting machines are used
to measure strength in tension , compression and shear respectively.
With application of load deformation is seen in specimen of a material
Within certain limits. The material behaves elastically, It comes to original shape and size when
load is removed. The limit is known as elastic limit during which the deformation is temprory.
The deformation is permanent when load is increased beyond elastic limit . It can take
maximum load to ultimate limit and fail/breaks, when further loaded.
The resistance offered by the material under the application of the load is known as stress(p)
Stress = applied force(F) / area of cross-section (A) = F/A Kg/cm2
The deformation per unit known as strain (e), can be expressed as, change
/original dimension . Condering guage length of a specimen under tension.
STRAIN = (L1-L2)/L
in dimension
Where L is guage of unloaded specimen
L1 is guage length on deformation
HOOKE’S LAW
Robert HooKe experimentally verified , that “within elastic limit, stress is
directly proportional toth strain”.
Stress
Stress = constant
Strain
OR
Stress/strain=constant
This constant is called as “Modulus of Elasticity” and represented by
p
E=
Where p =stress
e
e = strain
DIAGRAM NO 3
STRESS STRAIN DIAGRAM
It’s a graph between stress and strain when load is applied gradually on a test
specimen during experimentation.
During experimentation data for the change in dimensions in corresponding to
applied load.The stress and strain is worked out on the basis of recorded data.
A curve is drawn between stress and strain known as stress strain diagram as shown:
Diagram no 4
As appearance from the above diagram uner gradual loading condition ,
the strain is praportionatestress. The point ‘a’ represent the elastic limit of
proportionity. The slope of this straight line is known the “modulos or elasticity” or
Young’s Modulus, which shows the stiffness of the material .
Beyond elastic limit the stress is not proportionate and deformation is fast
and permanent. The specimen can take maximum load corresponding to point ‘d’ . The
point is known as ultimate point.
The little increment in load may result in breaking of test specimen. The
deformation is very and specimen breaks at pot e.
The strength corresponding yoeld point , ultimate ooint and breaking point
is known as yield strength or ultimate strength and breaking strength of material.
The percentage elongation can be worked out by measuring the guage
length of broken specimen.
The shear strength of a material is generally about 50% of its tensile
strength and the torsion strength about 75%.
In most of the non-ferrous metals it is difficult to locate the yield point.
ELASTICITYElasticity if material is the property of regaining original shape after deformation.
All the material are elastic, but their degree of elasticity varies with material to material.
It’s the desirable property of precisi machine’s and measuring instrument. Steel is said
to be a highly elastic material.
PLASTICITY
Plasticity of the material is the ability of the material to resust deformation .
The plastic material can be easily shaped . Under the application of the force.
STIFFNESS
Stiffness is the property of the material to resist deformation . property helps in
retaining shape in the case of the beams, coulumns and component of machine tools.
DUCTILITY
It is the ability of the material to drawn out under the application of tensile force.
Ductile material can be drawn in the form of wires. The material having percentage of
elongation more than 15% are said to be a ductile material.
BRITTLENESS
The material which breaks easily under the application of the load without
showing appricible elongation . It is known as Brittle material and this property of
material is known as brittleness. Brittleness is the property opposite to that of the
Ductility. The material having percentage less than 5% are said to be a brittle material.
HARDNESS
Hardness can be defined as the resistance to penetration . Material said to be
hard when no impressior is seen when a hard point is pressed on a material surface.
Hardness of the material can be measured by Vickers, Brinell hardness number Rockwell
hardness number . It is the desirable property for cutting tools, High carbon steel, High
speed steel, carbidres are hard materials are used for making cutting tools.
MALLEABILITY
It is the property of material to undergo the great change in shape under
compressive loads, Malleable materials such as wrought ion, copper silver etc. can be
easily shaped in the form of sheets and other rolled section in hot and cold condition.
TOUGHNESS
It is the capability of the material to take impact load. Toughness of material
is measured by means of charpy or lzod impact testing machine.
WEAR
Wear can be defined as the progressive loss or the removal material from a
surface. Wear generally alerts a part’s surface topography and may result in severe
surface damage.
RESILIENCE
It is the ability of the material to store energyand resist shocks and impact.
The material used of making springs need to have resilience.
CREEP
It is the property of material due to which the material is progressively
deformed at a slow rate when subjected to constant stress at elevated temperature for
a very long time, as in the case of steam turbine blades.
INDURANCE AND FATIGUE STRENGTH
Fatigue is the phenomenon thatleads to failure when a material is subjected
to cyclic loading results in variation in amount and nature of stresses.
The component fails with the initiation of crack on cyclic loading.
METAL STRUCTURE
Atom Arrangement in Metals
Based on arrangement of atoms the materials are classified as crystalline or
amorphous.The most of the metals have the crystalline structure in which atoms are
arranged in a regular geometric pattern are known as lattices.Lattices are unit building black
that is essentially repeated throughout space in a repetitive manner. These block are known as
unit cells.Arrangement of the atoms has a significant effect on the material properties.
Dig.5
Dig.6
S.No
phase
Important
properties
Frrite
Ferrite is the grain
or crystal of sold
solution of in
alphairon.
It is having BCCcrystal
structure.It is relativity
soft,ductile and strongly
magnetic.
Austenite
Austenite is a sold
solution of carbon
in gama-iron.It is
having BCC crystal
structure.
It is generally soft and
ductile than ferrite ,but
denser than ferrite ,and
is non-megnetic.
Cementite
Cementite is a
chemical compound
of 93.33% and
6.67% carbon.It is
having
orthorhombic
structure.
It is having round
particals in the
strycture.It is extremely
hard having about1400
brinell and brittle. It has
no ductility.
Pearlite:
Pearlite can be
recognized by its
pearly lustruous
appearance and its
structure of thin
alternating plates of
13 per cent
Pearlite is a strong
metalhaving medium
hardness.
1
2
3
4
Crystal
Structure
cementite in a
matrix of 87 per
cent ferrite.
Ledeburite
5
Sorbite:
6
7
Ledeburite
mixture of
austenite and
cementite.
It is reeated hard.
Sorbite it is a finely
dispersed perlite,
and the properties
are intermediate
between those of
pearlite and
troostite.
It is related hard.
Troostite Troostite or bainite
or
It is the most finely
baninite acicular (needlelike) structure of
austenite
decomposition. It is
composed of two
equilibrium phases
of ferrite and
cementite.
It has mediunm
Hardness.
8
Martensite
Martensite is
obtanined by
decomposition of
austenite when it is
very apidly cooled .
It is composed or
needle-like crystal
in angular
arrangements
Martensite is very hard,
brittle and magnetic.
COMMON ENGINEERING MATERIAL FOR WORK AND TOOLS
The common material used in the workshop for the work and tools can be
grouped in two category as metallic or non-metallic. The metallic material are further
classified as ferrious and Non-ferrous mater. The ferrous material consists of mainly
Ironwith comparitelively small addition of other elements. Non Ferrous material
contains or no iron.
FERROUS METAL
Ferrous metal are Iron and its alloy such as pig iron , cast iron , wrought iron
and steels.
PIG IRON
On processing iron in the blast furnace pig iron is obtained. Pig iron contains
about 92% iron and other element like carbon silicon, magnese, sulphur and
phosphorous. Pig iron is used to get cast iron and wrought by remelting.
CAST IRON
Cast iron is an alloy of iron , carbon and silicon . The carbon content in the cast
iron varies from 1%to 3% is obtained by reelting and refining the pig in a cupola furnace.
The presence of carbon in the caast iro is either in the form of the free carbon (grapite)
or in the form of iron carbide.Fe3C.
GREY CAST IRON
Grey cast iron contents crbon in the form form of or in the form of the graphite
. It is known grey cast iron on account of itsgreyish structure . It is having high
compressive strength and damping property . The material have excellence machiibility
due to presence of free carbon and a low cost. It is widely been used for making
components for machine used for supporting the other part of the assembley such as
base, etc. It can be shaped continently by casting process.
Cast iron is a brittle material lacking in ducktility and poor in shocks resistanc. It has
restricted yse for components subjected to tensile stress and sudden applied loads.
WHITE CAST IRON
In white cast iron carbon is present in the form of iron carbide. It has whitish
appearance. Iron carbide is a hard and brittle substance and presence increase the
hardness in the casting. White cast iron is almost unmachinable and has got the
restricted use for the parts . which required abrasion resistance. For processing
malleable cast iron castings are made from white cast ironand then it is treated to
convert them in to malleable cast iron casting.
WROUGHT IRON
Wrought iron is a highly refined iron with small amount ofslag forged out in to
fibre. It can have purity of 99.9% iron and the impurities of silicates may be in the form
of mechanical mixture. It has important properties of ductility and malleability and
toughness. Wrought iron is suitable for machine parts to shaped forging . It has
excellent weldability.
Bolts and nuts, chains,crains hooks railway couplings , pipes and pipe fitting ,
plates, bar and boiler are theprinciple form in which Wrought iron is used.
STEEL
It is an alloy of carbon in which carbon content is less than 10.5% .It also
contains the small% of phosphorous ,magnese etc. but the carbon , is most important
modifying element. Steels are classified as:
1. Plain carbon steel
2. Speccial carbon steel
3. Alloy steel
Plain carbon steel according their carbon contents may be divided in to 4 division as:
Low carbon or mild steel
0.05 to 0.45% carbon
Medium carbon steel
0.45 to 0.80%carbon
High carbon steel
0.80 to 1.65 % carbon
Tool steel
1.00 to 1.50% carbon
The mild steel and the medium carbon steel are widely used, as basic raw material
for many machine components, Whle high carbon and tool steel mainly used for making tools.
MILD STEEL
The low carbon steel has been sub divided as dead mild steel and mild steel . Dead
mile steel contains carbon up to 0.1%. It is softest and most ductile metal and has excellent
machinibility and weldebility . It can be rolled in to sheets . It is also used for rivets and solid
drawn steel tubes.
Mild steel contains carbin ranging from 0.1% to 0.45%. It has excellent welding properties and
machinibility .It is harder than dead mild steel but less ductile . It is mainly used for plate work,
bar for generalwork and rolled steel for section for structural work.
MEDIUM CARBON SEEL
Medium carbon steel contains carbon ranging from 0.45% to 0.8%. With increasing
carbon content the strength end hardness increase but ductility decreases .Increasing carbon
content also affecting the welding properties and machinability. Axies,gears,shafts, rals are
some of the well- known components of medium carbon steel on account of high strength and
wear resistance . The material has recolling properties as such also used for making spring.
HIGH CARBON AND TOOL STEEL
High carbon and tool steel contains rangingfrom0.45 to 0.8 %.With increasing
content the strength and hardness increases but ductility decreases, Incresing carbon content
also affecting the welding properties and machinibility. Axess, gears ,shaft, rails are some of the
well-known components of medium carbon steel on account of high strength and wear
resistance. The material has recolling properties as such also used for making springs.
HIGH SPEED STEEL
High –speed steel is an alloy in which element other than carbon is added in
sufficient amount to achievebetter properties. High heat hardness and wear resistance restrict
the use of plain carbon steel , to cut metal at low cutting speed. Alloying is done for specific
purpose to improve high heat hardness, wear resistance, corrosion resistance, electric and
magnetic properties . Nickel, chromium, molybdenium, cobalt, vanadium, magnese, silicon and
cobalt are some of the important alloying elements.
NICKEL
Nickel in steel contribute great strength and hardnes. With high elastic limit and good ductility
and good resistance to corrosuion.
CHROMIUM
The present of chromium improves hardness combined with high strength and high elastic limit
. It also improve strength. The large% of chromium in stainless steel is responsible for corrosion
resistance.
TUNGSTON
It improves the hot harness , which makes possible to cut at high cutting speed.
Vanadium
Vanadium along with chromium has extremely good tensile strength,elasticlimit and
ductility.These steels are frequently used for parts such as spring, shaft gear etc.
MANGANESE
Manganese improves the strength of steel in both hot rolled and heat-treated condition
SILICON
Silicon steel hass the properties similar to nickel steel.
COBALT
It is added to the steel to improve the hot hardness.
High-speed steel is the general purpose metal for low and medium cutting speeds owing to its
superiors hot-hardness and resistance to wear 18:4:1 high speed contains 18%tungston4%
chromium and 1%vanadium is considered as an important all purpose cutting tool material.
COST COMPARISION CHART
Iron-carbon phase diagram
Iron-carbon phase diagram describes the iron-carbon system of alloys containing up to 6.67%
of carbon, discloses the phases compositions and their transformations occurring with the alloys
during their cooling or heating.
Carbon content 6.67% corresponds to the fixed composition of the iron carbide Fe3C.
The diagram is presented in the picture:
The following phases are involved in the transformation, occurring with iron-carbon alloys:

L - Liquid solution of carbon in iron;

δ-ferrite – Solid solution of carbon in iron.
Maximum concentration of carbon in δ-ferrite is 0.09% at 2719 ºF (1493ºC) – temperature of the
peritectic transformation.
The crystal structure of δ-ferrite is BCC (cubic body centered).

Austenite – interstitial solid solution of carbon in γ-iron.
Austenite has FCC (cubic face centered) crystal structure, permitting high solubility of carbon –
up to 2.06% at 2097 ºF (1147 ºC).
Austenite does not exist below 1333 ºF (723ºC) and maximum carbon concentration at this
temperature is 0.83%.

α-ferrite – solid solution of carbon in α-iron.
α-ferrite has BCC crystal structure and low solubility of carbon – up to 0.25% at 1333 ºF
(723ºC).
α-ferrite exists at room temperature.

Cementite – iron carbide, intermetallic compound, having fixed composition Fe3C.
Cementite is a hard and brittle substance, influencing on the properties of steels and cast irons.
The following phase transformations occur with iron-carbon alloys:
Alloys, containing up to 0.51% of carbon, start solidification with formation of crystals of δferrite. Carbon content in δ-ferrite increases up to 0.09% in course solidification, and at 2719 ºF
(1493ºC) remaining liquid phase and δ-ferrite perform peritectic transformation, resulting in
formation of austenite.
Alloys, containing carbon more than 0.51%, but less than 2.06%, form primary austenite crystals
in the beginning of solidification and when the temperature reaches the curve ACM primary
cementite stars to form.
Iron-carbon alloys, containing up to 2.06% of carbon, are called steels.
Alloys, containing from 2.06 to 6.67% of carbon, experience eutectic transformation at 2097 ºF
(1147 ºC). The eutectic concentration of carbon is 4.3%.
In practice only hypoeutectic alloys are used. These alloys (carbon content from 2.06% to 4.3%)
are called cast irons. When temperature of an alloy from this range reaches 2097 ºF (1147 ºC), it
contains primary austenite crystals and some amount of the liquid phase. The latter decomposes
by eutectic mechanism to a fine mixture of austenite and cementite, called ledeburite.
All iron-carbon alloys (steels and cast irons) experience eutectoid transformation at 1333 ºF
(723ºC). The eutectoid concentration of carbon is 0.83%.
When the temperature of an alloy reaches 1333 ºF (733ºC), austenite transforms to pearlite (fine
ferrite-cementite structure, forming as a result of decomposition of austenite at slow cooling
conditions).
Critical temperatures

Upper critical temperature (point) A3 is the temperature, below which ferrite starts to
form as a result of ejection from austenite in the hypoeutectoid alloys.

Upper critical temperature (point) ACM is the temperature, below which cementite
starts to form as a result of ejection from austenite in the hypereutectoid alloys.

Lower critical temperature (point) A1 is the temperature of the austenite-to-pearlite
eutectoid transformation. Below this temperature austenite does not exist.

Magnetic transformation temperature A2 is the temperature below which α-ferrite is
ferromagnetic.
Phase compositions of the iron-carbon alloys at room temperature

Hypoeutectoid steels (carbon content from 0 to 0.83%) consist of primary (proeutectoid)
ferrite (according to the curve A3) and pearlite.

Eutectoid steel (carbon content 0.83%) entirely consists of pearlite.

Hypereutectoid steels (carbon content from 0.83 to 2.06%) consist of primary
(proeutectoid)cementite (according to the curve ACM) and pearlite.

Cast irons (carbon content from 2.06% to 4.3%) consist of proeutectoid cementite C2
ejected from austenite according to the curve ACM , pearlite and transformed ledeburite
(ledeburite in which austenite transformed to pearlite).