NATIONAL INSTITUTE OF TECHNOLOGY TIRUCHIRAPPALLI

Manufacturing Technology (MEPC16)

Dr. Vineet Kumar Yadav

Assistant Professor, Department of Production Engineering,
National Institute of Technology Tiruchirappalli,
Tiruchirappalli- 620015, Tamil Nadu, India.
Email: vineet@nitt.edu
Syllabus
Unit 1: Introduction to manufacturing process - Selecting manufacturing process – global
competitiveness of manufacturing costs – Fundamentals of materials – their behavior and
manufacturing properties– Ferrous metals and alloys – Non-Ferrous metals and alloys.
Unit 2: Casting: Solidification of Alloys and its mechanism – Gating system design and
estimation of solidification time – Riser Design and Riser placement – Defects and Product
Design.
Welding: Physics of Arc sources – Welding equipment's - Types of welding processes –
Electrode designation and fluxes – Principle and application of Special welding processes.
Brazing and Soldering.
Unit 3: Forming process: Forging, Rolling, Drawing, Extrusion – Classification, Defects
and Inspection.
Sheet metal forming process: Shaping process for plastics – Extrusion, Injection and
Compression Molding.
Unit 4: Machining process: Various machining process and its working principles – Metal
Cutting: Tool geometry – single edge tools – reference plane – Tool specifications –ASA,
NRS – Mechanics of Orthogonal cutting and Oblique cutting – Tool wear and Tool life –
Economics of Machining.
Unit 5: NC & CNC machine tools and manual part programming Machining centre. NC part
programming – Computer aided part programming - Rapid Prototyping processes:
Stereolithography, Fused Deposition modelling, 3D Printing, Selective laser sintering –
Rapid Tooling techniques.
Outline

• Introduction
• Manufacturing Processes
• Casting
• Welding
• Forming
• Machining
• NC and CNC Systems
Acknowledgements:
• M. P. Groover, Fundamental of modern manufacturing Materials, Processes and systems
• J. T. Black and R. A. Kohser, Materials and processes in manufacturing
• P N Rao, Manufacturing Technology (Vol. I and II)
• S. Kalpakjian and S. R. Schmid, Manufacturing Engineering & Technology
 Casting Welding

Forging (one of the forming process) Machining

Manufacturing

These products are produced by a combination of various processes.

Products & No. of Parts

Single material products Multi material (parts) products 12,000 parts

> 5,000 parts > 6 million parts

What is Manufacturing?

• The word manufacturing is centuries old and derived from two Latin words
manus (hand)
factus (make)
Hence, manufacturing literally means made by hand.
• Although modern manufacturing is accomplished by automated and computer-
controlled machinery, the word manufacturing is still in use.
Manufacturing is the economic term for making goods and services available to
satisfy human wants.
Manufacturing Process
Process- often implies a sequence of steps
A manufacturing process converts unfinished materials to finished products, often
using machines or machine tools.
What is Manufacturing?

Manufacturing can be defined in two ways; technologically and economically.

• Technologically: Manufacturing is the application of physical and chemical
processes to alter the geometry, properties, and/or appearance of a starting material
to make products. Manufacturing also includes assembly of multiple parts to make
products.
What is Manufacturing?

• Economically: Manufacturing is the transformation of materials into items of greater

value by means of one or more processing and/or assembly operations.
Manufacturing adds value to the material either by changing its shape or properties or
by combining it with other materials that have been similarly altered.

• Conversion of iron ore into steel

• Conversion of sand ore into glass
• Conversion of petroleum into plastic
• Conversion of plastics ore into chair
Engineering Materials
Materials in Manufacturing
Metals in Manufacturing
Metals used in manufacturing are usually alloys, which are composed of two or more
elements, with at least one being a metallic element.
Metals and alloys can be divided into two basic groups:
1. Ferrous- Based on iron
• Steel
• Cast Iron
2. Non-Ferrous- other metallic elements and their alloys
• Aluminum, Copper, Gold, Magnesium, Nickel, Silver, Tin, Titanium, Zinc, etc.
Ceramics in Manufacturing
A compound containing metallic (or semi-metallic) and nonmetallic elements.
• Traditional ceramics: Clay, Silica (used to make glass products), Alumina, Silicon carbide
• Newer Ceramics: Carbides, Nitrides
Polymers in Manufacturing
polymer is a compound formed of repeating structural units called ‘mers’
• Thermoplastic polymers: Polyethylene, Polystyrene, Polyvinylchloride, Nylon
• Thermosetting polymers: Phenolics, Amino resins, Epoxies
• Elastomers: Natural rubber, Neoprene, Silicone, Polyurethane
Composites in Manufacturing
Composites do not really constitute a separate category of materials; they are mixtures
of the other three types (metals, ceramics, and polymers).
A composite is a material consisting of two or more phases that are processed
separately and then bonded together to achieve properties superior to those of its
constituents.
e.g.
• Wood (Natural composite)
• Fiber-reinforced plastic (glass fibers in a polymer matrix)
• Epoxy-Kevlar composite (polymer fibers of one type in a matrix of a second
polymer)
• Cemented carbide cutting tool (tungsten carbide in a cobalt binder)
Classification of manufacturing processes
Casting

Forming
Machining

Welding

M.P. Groover, Fundamental of modern manufacturing Materials, Processes and systems, 4ed
Selection of manufacturing processes
• Required materials
• Required geometry Identify

• Number of parts
• Required tolerances Evaluate
• Cost (including tools and materials cost)
• Required level of automation Select

e.g.
Material choice will instantly rule out a vast number of unsuitable processes. Many processes work
exclusively with certain materials.
e.g. injection moulding can only be used with polymers, whilst die casting can only be used with
metals.
Selection of manufacturing processes

Casting
 Primary shaping
 Pouring molten metal in to the moulds and allow it
to solidify
– Examples: metal casting, plastic moulding
Selection of manufacturing processes
Joining
 These operations join two or more components to create a new entity
 Mechanical Fastening
 Welding
 Adhesive Joining
Selection of manufacturing processes
Forming and shaping
 Applying forces or pressure and plastically deform the material to produce the
desired shape
 Typically used for metal
 Examples:
 Forging
 Rolling
 Extrusion etc.
Selection of manufacturing processes
Machining
 Secondary shaping process
 Excess material removed with the help of tool to obtain the desired geometry
 Examples: turning, drilling, and milling; also grinding and non-traditional processes
 Metals, Plastics, wood etc.
Selection of manufacturing processes

http://changsung.com/_new/eng/products/%EA%B8%88%EC%86%8D%EB%B6
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Powder Metallurgy
 Powder manufacture,
 Blending of powders,
 Compacting of powders in a
mould or die
 Sintering.
Manufacturing Costs and Global Competition
• Economics of manufacturing
 ever-increasing global competition and
 the demand for high-quality products, generally referred to as world-class
manufacturing, at low prices.
• The manufacturing cost of a product represents about 40% of its selling price. The
total cost of manufacturing a product generally consists of the following
components:
 Materials cost
 Tooling cost
Typical Cost Breakdown in Manufacturing
 Fixed cost
 Capital cost Manufacturing
Design 5% Materials 50%
45%
 Labor cost
 Direct cost
Direct labor 15%
 Indirect cost
• Outsourcing can reduce the labor cost.
Indirect labor 30%
Selection of Materials
• Materials were selected because they possess desired properties and characteristics
for the intended functions

S. Kalpakjian and S. R. Schmid, Manufacturing Engineering & Technology

• Task of engineers becomes very challenging when ever-increasing variety of
materials are now available

S. Kalpakjian and S. R. Schmid, Manufacturing Engineering & Technology

• Material behavior, properties and characteristics will help the engineer understand
their relevance to the manufacturing processes

S. Kalpakjian and S. R. Schmid, Manufacturing Engineering & Technology

Four Types of Engineering Materials
Metals
• The most important engineering materials.
• They have properties that satisfy a wide variety of design requirements.
• The manufacturing processes by which they are shaped into products have been
developed and refined over many years.
• Engineers understand metals.
Why metals are important
• High stiffness and strength - can be alloyed for high rigidity, strength, and
hardness
• Toughness - capacity to absorb energy better than other classes of materials
• Good electrical conductivity - Metals are conductors
• Good thermal conductivity - conduct heat better than ceramics or polymers
• Cost – the price of steel is very competitive with other engineering
materials
Starting Forms of Metals
Starting Forms of Metals used in Manufacturing Processes are
• Cast metal - starting form is a casting
• Wrought metal - the metal has been worked or can be worked after casting
• Powdered metal - starting form is very small powders for conversion into
parts using powder metallurgy techniques
Classification of Metals
• Metals in Manufacturing
• Metals used in manufacturing are usually alloys, which are composed of two or
more elements, with at least one being a metallic element.

1. Ferrous- those based on iron

• Steel

• Cast Iron

2. Non-Ferrous- all other metallic elements and their alloys

• Aluminum, magnesium, copper, nickel, titanium, zinc, lead, tin, molybdenum,

tungsten, gold, silver, platinum, and others

3. Superalloys
Metals and Alloys
• Some metals are important as pure elements (e.g., gold, silver, copper).

• Most engineering applications require the enhanced properties obtained by alloying.

• Through alloying, it is possible to increase strength, hardness, and other properties

compared to pure metals.
Alloys
• An alloy = a mixture or compound of two or more elements, at least one of which is
metallic.

• Two main categories:

 Solid solutions

 Intermediate phases
Solid Solutions
• An alloy in which one element is dissolved in another to form a
single-phase structure.
• A phase = any homogeneous mass of material, such as a metal in which the
grains all have the same crystal lattice structure.
• In a solid solution, the solvent or base element is metallic, and the dissolved
element can be either metallic or nonmetal.
Solid Solutions
• Two forms of solid solutions
 Substitutional solid solution - atoms of solvent element are replaced in its
unit cell by dissolved element
 Interstitial solid solution - atoms of dissolving element fit into vacant spaces
between base metal atoms in the lattice structure
In both forms, the alloy structure is generally stronger and harder than either of
the component elements

(a) Substitutional solid solution, (b) interstitial solid solution

Intermediate Phases
 There are usually limits to the solubility of one element in another.
 When the amount of the dissolving element in the alloy exceeds the solid
solubility limit of the base metal, a second phase forms in the alloy.
 The term intermediate phase is used to describe it because its chemical
composition is intermediate between the two pure elements.
 Its crystalline structure is also different from those of the pure metals.
Types of Intermediate Phases
 Metallic compounds – consist of a metal and nonmetal, such as Fe3C
 Intermetallic compounds - two metals that form a compound, such as
Mg2Pb.
 In some alloy compositions, the intermediate phase is mixed with the
primary solid solution to form a two-phase structure.
 Some two-phase alloys are important because they can be heat treated for
much higher strength than solid solutions.
Phase Diagrams
• A graphical means of representing the phases of a metal alloy system as a
function of composition and temperature.
• A phase diagram for an alloy system consisting of two elements at
atmospheric pressure is called a binary phase diagram.
• Composition is plotted on the horizontal axis and temperature on the
vertical axis.
• Any point in the diagram indicates the overall composition and the phase or
phases present at the given temperature under equilibrium conditions.
Phase Diagrams

Binary phase diagram for copper-nickel alloy system

Steel and Cast Iron
• Steel = an iron-carbon alloy containing from 0.02% to 2.1% carbon.
• Cast iron = an iron-carbon alloy containing from 2.1% to about 4% or 5%
carbon.
• Steels and cast irons can also contain other alloying elements besides
carbon.
Iron and Steel Production
 Iron making - iron is reduced from its ores
 Blast furnace
 Steel making – iron is then refined to obtain desired purity and composition
(alloying)
 Principal ore used in the production of iron and steel is hematite (Fe2O3)
 Other iron ores include magnetite (Fe3O4), siderite (FeCO3), and limonite
(Fe2O3-xH2O, where x is typically around 1.5)
 Iron ores contain from 50% to ~ 70% iron, depending on grade (hematite is almost 70%
iron)
 Scrap iron and steel are also widely used today as raw materials in iron- and steel
making
Steel-making
• Since the mid-1800s, a number of processes have been developed for
refining pig iron into steel
• Today, the two most important processes are
 Basic oxygen furnace (BOF)
 Electric furnace
• Both are used to produce carbon and alloy steels
Steel
• An alloy of iron containing from 0.02% and 2.11% carbon by weight.
• May contain other alloying elements.
• Steel alloys can be grouped into four categories:
 Plain carbon steels
 Low alloy steels
 Stainless steels
 Tool steels
 Specialty steels
Plain Carbon Steels
• Carbon is the principal alloying element, with only small amounts of other
elements (about 0.5% manganese is normal)
• Strength of plain carbon steels increases with carbon content, but ductility is
reduced
• High carbon steels can be heat treated to form martensite, making the steel
very hard and strong
 Low carbon steels - less than 0.20% C
• Applications: automobile sheetmetal parts, plate steel for fabrication, railroad
rails
 Medium carbon steels - between 0.20% and 0.50% C
• Applications: machinery components and engine parts such as crankshafts and
connecting rods
 High carbon steels - greater than 0.50% C
• Applications: springs, cutting tools and blades, wear-resistant parts
Low Alloy Steels
• Iron-carbon alloys containing additional alloying elements in amounts
totaling less than 5% by weight.
• Mechanical properties superior to plain carbon steels for given applications.
• Higher strength, hardness, hot hardness, wear resistance, and toughness.
 Heat treatment is often required to achieve these improved properties.
Stainless Steel (SS)
• Highly alloyed steels designed for corrosion resistance.
• Principal alloying element is chromium, usually greater than 15%.
 Cr forms a thin impervious oxide film that protects surface from corrosion.
• Nickel (Ni) is another alloying ingredient in certain SS to increase corrosion
protection.
• Carbon is used to strengthen and harden SS, but high C content reduces
corrosion protection since chromium carbide forms to reduce available free
Cr.
Properties of Stainless Steels
• In addition to corrosion resistance, stainless steels are noted for their
combination of strength and ductility.
 While desirable in many applications, these properties generally make stainless steel
difficult to work in manufacturing.
• Significantly more expensive than plain C or low alloy steels.
Types of Stainless Steel
• Classified according to the predominant phase present at ambient
temperature:
 Austenitic stainless - typical composition 18% Cr and 8% Ni
 Ferritic stainless - about 15% to 20% Cr, low C, and no Ni
 Martensitic stainless - as much as 18% Cr but no Ni, higher C
content than ferritic stainless
Tool Steels
• A class of (usually) highly alloyed steels designed for use as industrial
cutting tools, dies, and molds
 To perform in these applications, they must possess high strength,
hardness, hot hardness, wear resistance, and toughness under
impact.
 Tool steels are heat treated.
Specialty Steels
• Maraging steels - low C alloys containing high Ni content (15% to 25%)
and lesser amounts of Co, Mo, and Ti (and sometimes Cr to resist corrosion)
 Strengthened by precipitation hardening.
• Free-machining steels - C steels formulated with small amounts of S, Pb,
Sn, and other elements to improve machinability
• Interstitial-free steels - extremely low C content (0.005%) for excellent
ductility for deep drawing
Cast Irons
• Iron alloys containing from 2.1% to about 4% carbon and from 1% to 3%
silicon.
• This composition makes them highly suitable as casting metals.
Types of Cast Irons
• Gray cast iron
• Ductile iron
• White cast iron
• Malleable iron
• Various alloy cast irons
Cast Iron Chemistries
Nonferrous Metals
• Metal elements and alloys not based on iron.
• Most important - aluminum, copper, magnesium, nickel, titanium, and zinc,
and their alloys
• Although not as strong as steels, certain nonferrous alloys have
strength-to-weight ratios that make them competitive with steels in some
applications
• Many nonferrous metals have properties other than mechanical that make
them ideal for applications in which steel would not be suitable
Nonferrous Metals
• Aluminum and its alloys
• Magnesium and its alloys
• Copper and its alloys
• Nickel and its alloys
• Titanium and its alloys
• Zinc and its alloys
• Lead and Tin
• Molybdenum
• Tungsten
Aluminum and Magnesium
• Aluminum (Al) and magnesium (Mg) are light metals.
 They are often specified in engineering applications for this feature.
• Both elements are abundant on earth, aluminum on land and magnesium in
the sea.
 Neither is easily extracted from their natural states.
Copper
• One of the oldest metals known to mankind.
• Low electrical resistivity - commercially pure copper is widely used as an
electrical conductor.
• An excellent thermal conductor.
• One of the noble metals (gold and silver are also noble metals), so it is
corrosion resistant.

Noble Metals are metallic elements that show outstanding resistance to

chemical attack even at high temperatures.
Copper and its Alloys
• Strength and hardness of copper is relatively low; to improve strength,
copper is frequently alloyed
• Bronze - alloy of copper and tin (typical  90% Cu, 10% Sn), widely used
today and in ancient times
• Brass - alloy of copper and zinc (typical  65% Cu, 35% Zn).
• Highest strength alloy is beryllium-copper (only about 2% Be), which can
be heat treated to high strengths and used for springs
Nickel and its Alloys
• Like iron in some respects:
 Magnetic
 Modulus of elasticity  E for iron and steel
• Differences with iron:
 Much more corrosion resistant - widely used as an alloying element in steel,
e.g., stainless steel, and as a plating metal on metals such as plain
carbon steel
• High temperature properties of Ni alloys are superior
Titanium and its Alloys
• Abundant in nature, constituting  1% of earth's crust (aluminum is  8%)
• Density of Ti is between aluminum and iron. (Stiffer and stronger than Al)
• Importance has grown in recent decades due to its aerospace applications
where its light weight and good strength-to-weight ratio are exploited.
• Coefficient of thermal expansion is relatively low among metals.
• Retains good strength at elevated temperatures.
• Pure Ti is reactive, which presents problems in processing, especially in
molten state.
• At room temperature Ti forms a thin adherent oxide coating (TiO2) that
provides excellent corrosion resistance.
Precious Metals
• Gold, platinum, and silver
 Called noble metals because chemically inert
• Available in limited supplies
• Used throughout civilized history for coinage and to underwrite paper
currency
• Widely used in jewelry and similar applications
• Properties: high density, good ductility, high electrical conductivity and
corrosion resistance, and moderate melting temperatures
Superalloys
• High-performance alloys designed to meet demanding requirements for
strength and resistance to surface degradation at high service temperatures.
 Many superalloys contain substantial amounts of three or more metals,
rather than consisting of one base metal plus alloying elements.
 Commercially important because they are very expensive.
 Technologically important because of their unique properties.
Why Superalloys are Important
• Room temperature strength properties are good but not outstanding.
• High temperature performance is excellent - tensile strength, hot hardness,
creep resistance, and corrosion resistance at very elevated temperatures
• Operating temperatures often ~ 1100C
• Applications: gas turbines - jet and rocket engines, steam turbines, and
nuclear power plants (systems that operate more efficiently at high
temperatures)
Three Groups of Superalloys
• Iron-based alloys - in some cases iron is less than 50% of total composition
 alloyed with Ni, Cr, Co
• Nickel-based alloys - better high temperature strength than alloy steels
 alloyed with Cr, Co, Fe, Mo, Ti
• Cobalt-based alloys -  40% Co and  20% chromium
 alloyed with Ni, Mo, and W

Virtually all superalloys strengthen by precipitation hardening

Enhancing Mechanical Properties of Metals
• Alloying - to increase strength of metals
• Cold working - strain hardening during deformation to increase strength
(also reduces ductility)
 Strengthening of the metal occurs as a byproduct of the forming operation
• Heat treatment - heating and cooling cycles performed to beneficially
change its mechanical properties
 Operate by altering the microstructure of the metal, which in turn
determines properties