Product Design and Development 20ME43P C-20 Lab Manual.pdf

Vidya Vikas Educational Trust (R),
Vidya Vikas Polytechnic
27-128, Mysore - Bannur Road Alanahally,Alanahally Post, Mysuru, Karnataka 570028
Prepared by Mr. THANMAY J.S, HOD Mechanical, Vidya Vikas Polytechnic, Mysore. Page 1 of 58
Department of Mechanical Engineering
Laboratory Manual
Subject : Product Design and Development
Subject Code : 20ME43P
Semester : 4th
Semester
Branch : Mechanical Engineering [General]
Name of the Student: …………………………………………….
Register Number: …………………………………………….

Syllabus
Product Development and Design:
1. Explain Product Development-Stages of Product Development-Need and Feasibility study
2. Explain Development of design-Selection of Materials and Process
3. Explain Protype –launching of product –Product life cycle
General consideration in design Based on:
• Functional requirement
• Effect on environment
• Life, Reliability, Safety
• Principles of Standardization
• Assembly Feasibility
• Maintenance-Cost-Quantity
• Legal issues and Patents
• Aesthetic and Ergonomic factors
• Choice of Materials
• Feasibility of Manufacturing Processes
Aesthetic and Ergonomic consideration in Design:
• Explain Aesthetic considerations-Basic types of product forms, designing for appearance, shape, Design
features, Materials, Finishes, proportions, Symmetry Contrast etc.
• Morgan’s color code.
• Ergonomic considerations-Relation between man, machine and environmental factors.
• Design of displays and controls.
“Case Study on Ergonomics and Aesthetic design principles”.
Torsion of Shaft:
1. Assumptions in Shear stress in a shaft subjected to torsion –Strength and Rigidity (Solid and Hollow
shaft)
2. Power Transmitted by Solid and Hollow shaft - ASME and BIS Code for power Transmission
3. Problems on Shafts subjected to only Shear based on Rigidity and Strength
Validate the Problems on Shafts for Strength and Rigidity using Ansys (One each on Strength and
Rigidity)
1. Problems on Shafts subjected to only Shear based on Rigidity and Strength
2. Problems on Shaft subjected to only Bending
3. Problems on Shaft subjected to only Bending
Practice on Section of Solids
a) Prisms
b) Pyramid
1. Problems on Shaft subjected to combined Shear and Bending.
2. Problems on Shaft subjected to combined Shear and Bending
3. Problems on Shaft subjected to combined Shear and Bending
Practice on Section of Solids
a) Cylinder

b) Cone
Springs:
1. Classification of springs- Application of springs- Leaf springs –Application
2. Terminology of Helical spring-Materials and Specification of springs
3. Design of helical spring
Sections on Simple Machine Elements (CAD)
a) Sectional front view, Front view with Right half in Section, Front view with Left half in Section
b) Sectional Top View
c) Sectional Side View
Coupling:
i. Design of Muff coupling
ii. Design of Protected type Flange Coupling
iii. Design of Knuckle Joint
Using CAD, prepare Part Models for Muff coupling based on designed parameter and assemble the same.
Extract the Sectional views for the above machine element indicating Surface Texture and Bill of Materials
3D Printing
1. Introduction, Process, Classifications, Advantages of additive over conventional Manufacturing,
Applications, Modeling for Additive Manufacturing
2. Additive Manufacturing Techniques, 3D Printing Materials and its forms, Post Processing Requirement and
Techniques.
3. Product Quality, Inspection and Testing, Defects and their causes, Additive Manufacturing Application
Domains
Preparation of 3D Printer for printing – Modeling, Saving CAD file into STL file, Slicing, Material loading
and printing parameter selection
1. Working of Fused Deposition Modeling (FDM) Machine- Single and Multi Nozzle printers,
Machine Configuration- Cartesian, Delta, Polar and robotic arm configuration 3D printers
2. Common FDM materials- PLA, ABS, PA, TPU,PETG, PEEK and PEI, Printer Parameters – Temperature
of the nozzle and the platform, the build speed, the layer height, Warping, Layer Adhesion, Support Structure,
In-fill & Shell Thickness
3. Benefits & Limitations of FDM, Software Tools- 3D modeling, Slicers & 3D Printer Hosts

Product Development and Design:
1. Product Development
Product development typically refers to all stages involved in bringing a product
from concept or idea through market release and beyond. In other words, product
development incorporates a product’s entire journey.
Definition: Product development refers to the creation of a new product which has
some utility; or up-gradation of the existing product; or enhancement of the
production process, method or system. In simple words, it is all about bringing a
change in the present goods or services or the mode of production.
2. Stages of Product Development
Stages of Product Development includes process of generating, selecting, developing, and commercializing
product ideas.
a) Idea Generation
The first step in the new-product development process is to come up with some ideas that will satisfy unmet
needs. Customers, competitors, and employees are often the best source of new product ideas.
b) Idea Screening

From all the ideas under consideration, the company selects those that appear to be worthy of further
development, applying broad criteria such as whether the product can use existing production facilities and
how much technical and marketing risk is involved.
c) Business Analysis
A product idea that survives the screening stage is subjected to a business analysis. During this stage, the
company reviews the sales, costs, and profit projections to determine whether they meet the company's
objectives. Given these projections, analysts calculate the potential profit that will be achieved if the product
is introduced. If the product meets the company's objectives, it can then move to the prototype development.
d) Prototype Development
At this stage, the firm may actually develop a product concept into a functioning "prerelease" product. For
physical goods, the firm creates and tests a few samples, or prototypes, of the product, including its packaging.
These units are rigorously analyzed for usability, durability, manufacturability, customer appeal, and other
vital criteria, depending on the type of product.
Prototypes - Preproduction samples of products used for testing and evaluation.
e) Marketing Strategy
Once a company decides on the product, they will have to spend time developing a marketing strategy for it.
Experts will evaluate the size of the market, demand for the product, and revenue estimates. The marketing
team will get a budget for their efforts and they can select distribution channels.
f) Business Model
The development of a business model works very similarly to the development of a marketing strategy. The
experts in the company will estimate the costs and profits and manage the potential of the product. Also, they
will estimate the economic feasibility of the new product.
g) Manufacture
At this stage, the production finally begins. The company will make multiple prototypes and choose on which
designs get to go to the next stage. Also, the company will, once again, perform a cost analysis to see if it
matches the estimates. And if the costs go above the higher-end estimates, the company might abandon the
project.
h) Branding and Product Launch
Once the company finally has a physical product in their hands, the marketing team can get to work. For
starters, they can develop the brand name, packaging, and the marketing message behind the product. They
will also determine the price of the product.
The final phase of the product development process is the commercialization phase. The product is launched,
and it is followed by a developed marketing strategy in order to maximize its earning potential.
3. Need for Product Development

a) Meeting Changes in Consumer Demand:
Change is a universal phenomenon in today's time of science and technology. For example, a quick change in
the food habits, comfort preferences, tastes, customs and traditions, needs and expectations, etc.
b) Making New Profits:
In Product Development and Manufacturing it has becomes quite necessary for the organizations to come up
with the new and innovative products that can replace the old product which is on the verge of declining.
c) Handling the Environmental Threats:
There are various environmental threats, these threats spring from various environmental factors, like socio-
economic, technological, political, and demand and supply, etc. Moreover, the biggest threat that is always
present in such environment is competition in the market and products.
d) Other Necessities:
The other strategic needs for product development are as follows:
 New products can provide the organization a source for gaining competitive edge.
 They can ensure long-term financial return on the investments made. They also help in optimum
utilization of the available resources.
 New products make best use of research and development.
 They can provide new opportunities for making changes in the strategic plans of the company.
 New products can bring most out of the marketing practices and brand equity.
 It enhances the corporate image of the organization/brand.
4. Product Development Feasibility study
A new product feasibility study is a market research methodology that aims to provide predictive analytics to
guide the next steps for marketing, sales, and product development.
The objectives of this type of market research often include obtain insight on:
 Product placement
 The target market
 Marketing and advertising
 The competition
 Pricing strategies
There may also be several secondary objectives included in the study depending on your company's needs and
specifications.
For a product feasibility study Company conducts these type of market research.
a) Demographic analysis
b) Competitive assessments
c) Pricing analysis
d) Online surveys
e) Stakeholder interviews

5. Explain Development of design-Selection of Materials and Process
A Design Development is the design and engineering work process that is based on basic Engineering
information to develop the Detailed Design and Engineering document for the procurement, construction,
operation, and maintenance of a project. The Design Development defines and describes all important aspects
of the project focusing on the selection of materials; development of technical specifications for detailed
engineering and construction; and generation of construction drawings and document. During Design
Development, design issues should be resolved to fix the size and character of the entire project including
civil and structural, mechanical, and piping, control and electrical systems, and materials as well as other
operability and maintainability requirement.
Materials selection is an ordered process by which engineers can systematically and rapidly eliminate
unsuitable materials and identify the one or a small number of materials which are the most suitable. The
approaches adopted for materials selection are by far the most developed for this design discipline. There are
many systematic methods, most numerically based, with some implemented as computer software tools, for
matching material properties with technical design requirements. For a better Selection of Materials there are
5 steps
a) Bill of Materials [to know number of materials required, availability etc.]
b) Analysis of Performance, aesthetics and cost of production
c) Analysis of Prototype models using different materials and manufacturing techniques.
d) Evaluating the results and find the materials that satisfy the product-production needs.
e) Identification and selection of best results and update results to bill of materials
Manufacturing process selection is to establish selection criteria based on key process selection drivers:
manufacturing volumes, value of the product, part geometry, required tolerances, and required material.
The material choice will be very effective in narrowing your options down. This is because many processes
work exclusively with certain materials. For example, injection moulding can only be used with polymers,
whilst die casting can only be used with metals. Your material choice will instantly rule out a vast number of
unsuitable processes.
The expected manufacturing volume will further narrow down your process options. For a large quantity, a
manual production process like manual machining would be completely impractical. Instead, you would need
to consider an automated process such as moulding. The geometry and tolerances required for a product will
also filter out many processes that would be unable to achieve the desired accuracy.
6. Explain Prototype –launching of product –Product life cycle
Prototype “It is a simulation or sample version of a final product, which manufacturing teams use for testing
before launch.”

The goal of a prototype is to test and validate ideas before sharing them with stakeholders and eventually
passing the final designs to engineering teams for the development process.
Prototypes are a crucial part of the design process and a practice used in all design disciplines. From architects,
engineers, industrial designers and even service designers, they make their prototypes to test their designs
before investing in their mass production.
The purpose of a prototype is to have a tangible model of the solutions to the problems already defined and
discussed by the designers during the concept/idea stage. Instead of going through the entire design cycle based
on a supposed solution, prototypes allow designers to validate their concepts by putting an early version of the
solution in front of real users and collecting feedback as quickly as possible.
When Prototypes test fail it shows designers where the defects are and sends them “back to the design process”
to refine or repeat the proposed solutions. In prototype test we can understand early fails, prototypes can save
lives, avoiding the waste of energy, time and money in implementing weak or inappropriate solutions. Another
advantage of prototyping is that, because the investment is small, the risk is low
A Product launch is a planned effort to bring a new product to market. The goal is to make sure that everyone
inside the company, your partners and target customers know about your new product. If you don’t do the
product launch effectively, customers won’t be aware of your solution, or may potentially have a bad
impression of your product, and you may not hit your revenue and profitability goals.
A Product launch refers to a business’s planned and coordinated effort to debut a new product to the market
and make that product generally available for purchase. A product launch serves many purposes for an
organization— giving customers the chance to buy the new product is only one of them. It also helps an
organization build anticipation for the product, gather valuable feedback from early users, and create
momentum and industry recognition for the company.
A Product life cycle is the length of time from a product first being introduced to consumers until it is removed
from the market. A product’s life cycle is usually broken down into four stages; introduction, growth, maturity,
and decline.
Product life cycles are used by management and marketing professionals to help determine advertising
schedules, price points, and expansion to new product markets, packaging redesigns, and more. These strategic
methods of supporting a product are known as product life cycle management. They can also help determine
when newer products are ready to push older ones from the market.
7. General consideration in design:

The essential requirements of a good product design are listed as follows:
1. Product must optimally perform its main function (task).
2. It must be easy to repair at a low repair cost.
3. It must be very reliable to use.
4. It must follow principles of aesthetics.
5. It must be a durable one.
6. It can be easily produced in large numbers at minimum
production cost.
7. It must be simple to produce and use (handle).
8. It must also be compact.
8. Essential requirement of a good product design Based on:
a. Functional requirement
The product must be designed in such a way that it optimally performs the main task or function for which
it is purchased by a buyer. In other words, the product must satisfy the needs and wants of the consumer.
b. Effect on environment
Eco-design minimizes a product’s negative impact by factoring environmental concerns into its specifications,
such as the preservation of precious or non-renewable resources, the prevention of pollution and the absence
of danger for animal and plant species.
c. Life, Reliability, Safety
Durability refers to the life of a product. A durable product performs flawlessly for a longer period. It is a
sign of a good-quality product. Consumers want their products to have a longer life. The product must be
designed in such a way that it can be easily repaired whenever necessary during a malfunction. The product
repairs must be done quickly that too at a low repair cost.
Reliability means dependability on a product. Consumers prefer to purchase and use often those products
which perform their main function or task optimally for a longer period without any annoying malfunctions,
breakdowns or failures.
The designer must ensure that the products they design are safe to use. Quality products will have certificates
such as BSI, ISO, and other standards. Designers must create their products according to the regulations of
these organizations. Gaining these certificates validates the product's quality and tempts the general public to
buy and use these products
d. Principles of Standardization
The design of the product must be very simple. The simpler a design, the easier, it is to produce and use
(handle). Simple products are also economical and reliable. The product must have the least number of
operations without affecting its functionality.
e. Assembly Feasibility

Design for assembly is an Analysis of products that results in simplified product designs that are easier and
less costly to assemble, particularly by attempting to reduce the number of parts. It is primarily a cost-saving
tool that is concerned with reducing the product assembly cost by minimizing the part count, the number of
assembly operations needed to produce the part and by making these assembly operations as easy and fail-
proof as possible.
f. Maintenance-Cost-Quantity
Most of the designers concentrate more on functions and aesthetics, and forget about maintenance. Proper
maintenance can prolong the longevity of the product. Using durable materials for easy maintenance adds to
the overall cost of the product. But this cost can be justified.
Designers are trained to design a cost-efficient and higher quality product that will attract more consumers.
While designing a complementary product, the designer must consider the primary product's price and make
their plans accordingly.
g. Legal issues and Patents
Legal issues to consider during product development are
Licensing: Licensing your product basically gives someone else the right to produce and sell your product for
a given period of time.
Product Liability: some products may be recalled due to defects. There are manufacturing defects, which
you aren’t in control of, and design defects, which you most definitely are to be guaranteed for replacement
or warranted or money back policy or free services.
Patents: Patents are the best way to ensure that your invention is legally protected, should someone try to
copy your idea or challenge your ownership
h. Aesthetic and Ergonomic factors
Aesthetics must be kept in mind while designing a product. It refers to, how the product looks, feels, sounds,
tastes or smells. That is, the product must look, feel, sound, taste or smell very good. It must be attractive,
compact and convenient to use. Its packaging must also be made graphically appealing and colorful. If this
aspect is not considered, product will fail in the market.
Aesthetics is the final and most crucial factor that needs to be considered in product design. Customers have
their own aesthetics, and they purchase products guided by this sense. Even when the product quality is less
than other products of the same cost, consumers will recommend buying a product because of its aesthetics.
Ergonomics is defined as “The applied science of equipment design, as for the workplace, intended to
maximize productivity by reducing operator fatigue and discomfort”. Ergonomic design customizes a product
to meet specific user needs, we can surmise that ergonomic design is the process of developing a
product/service that is easy to use and provides a favorable, enjoyable experience for the end user. It involves
creating and designing a product in its most effective and useful form.
i. Choice of Materials

Before manufacturing a product, the designer must decide the material to be used. The designer must ensure
that their choices are compatible with each other. Since the materials used in their products also define its
quality and guarantee, the designer must have perfect knowledge about the product's materials.
j. Feasibility of Manufacturing Processes
The product must be designed in such a way that it can be produced in large quantities with ease at a
minimum production cost. The production department must be able to produce the product easily, quickly, in
ample quantities and at a low production cost. The production process must not be very complex, and it must
not require costly machines to produce the product.
9. Aesthetic and Ergonomic consideration in Design:
Aesthetic is defined as a set of principles of appreciation of beauty.
a. Aesthetic is deals with the appearance of the product. Appearance is the outward expression of quality
of the product and is the first communication of the product with the user is nothing but the appearance
of the product.
b. Now days, number of products available in the market are having most of the parameters identical, so
the appearance of the product plays a major role in attracting the customer.
c. To compete and succeed in the market place, manufacturers will have to look beyond reliability and
physical quality, and pay more and more attention to the aesthetic and subjective quality of the product.
i. Aesthetic basic types of product forms
Form (Shape): form is the image presented by the outer surface of an object or structure. There are 05 basic
types of the products namely, step, taper, shear, streamline and sculpture.
a. Step form: - structure having vertical ascent. Ex. Multi-store building.
b. Taper form: - It consists of tapered blocks or taper cylinders.
c. Shear form: - It has a square outlet.
d. Streamline form: - It has a streamlined shape having a smooth flow as seen in automobile and aero
plane structures.
e. Sculpture form: - It consists of ellipsoids, paraboloids and hyperboloids.
ii. Aesthetic designing for appearance
 The appearance should contribute to the performance of the product. Example, the aerodynamic
shape of the car will have a lesser air resistance, resulting in lesser fuel consumption.
 The appearance should reflect the function of the product. Example, the aerodynamic shape
indicates the speed.
 The appearance should reflect the quality of the product. Example, the robust and heavy appearance
of the hydraulic press reflects its strength and rigidity.
 The appearance should not be at too much of extra cost unless it is a prime requirement.

 The appearance should be achieved by the effective and economical use of materials.
 The appearance should be suitable to the environment in which the product is used.
iii. Aesthetic design features
Aesthetics are in all our senses, not just the sight. There are 4 important categories, which can make or break
the aesthetics of our designs.
a) Vision: The most dominant sense in majority of people is our sight. We can’t stop ourselves to look at
what we find beautiful. Visual aesthetics have these key elements: Color, Shape, Pattern, Line, Texture,
Visual, weight, Balance, Scale, Proximity and Movement.
b) Hearing: Our ears are capable of perceiving a whole another level of aesthetic design. Sound aesthetics
have these key elements: Loudness, Pitch, Beat, Repetition, Melody, Pattern and Noise.
c) Touch: Skin is the largest organ in human body. It also helps us experience the aesthetics. Material
aesthetics are especially important for physical products. Material aesthetics key elements are: Texture,
Shape, Weight, Comfort, Temperature, Vibration and Sharpness.
d) Taste and Smell: Taste and Smell are sense that help us experience aesthetics even more deeply.
Especially in food industry and different environment designs, these senses play an important role in
experiencing aesthetics. Key elements are: Strength, Sweetness, Sourness and Texture (for taste).
iv. Aesthetic Materials
In aesthetic meaning, material (stone, wood, metal, concrete, etc.) is a medium, with visual and sensory form
recording creations of the artists. In virtue of its criteria, materialness is an essential component of artistic
creation. Materials make influence in the aspect of engineering structures, they are fundamental for the shape
of engineering structures. Durability, mouldability, texture, color and load capacity of the materials are
important factors of aesthetic quality
Aesthetic analysis of the material points out two factors fundamental from the aspect of construction:
1. Particulars (inner structure, color, texture etc.),
2. Decision over the structure (strength, physical characteristics).
In Mechanical manufacturing of products beside steel, Alumunium is a valuable, developing structural
material. Its structural aesthetics resides in its homogeneity. Anticorrosion, weathering resistance, water
tightness and metallic surface. It needs no painting: its color, shine and materialness are of a special aesthetic
value.
v. Aesthetic Finishes
Aesthetic Finishes change appearance and also make attractive, Finishes are added to a product’s surface after
production to improve its functionality and/or aesthetic. They can be applied to:
 stop corrosion
 prevent decay

 stop UV light degradation
 Defend against attack (from insects or fungus etc.)
 improve hygiene
 make a product tougher
 insulate
 decorate
 color
 make a product smooth
vi. Aesthetic proportions
Proportion is one of the aesthetic elements in product design. It has been widely considered in aesthetic
researches. There exist various types of proportion such as stability proportion, usability proportion,
functionality proportion, aesthetics proportion, conventionality proportion and harmony proportion and each
product category has its own important types of proportion. Because each product category has its own
important types of proportion, designers should know the important elements expressed by proportion first
before they consider proportion in product design
vii. Aesthetic Symmetry Contrast
Contrast refers to how different elements are in a design, particularly adjacent elements. These differences
make various elements stand out. Contrast is also a very important aspect of creating accessible designs.
Balance: Every element of a design—typography, colors, images, shapes, patterns, etc.—carries a visual
weight. Some elements are heavy and draw the eye, while other elements are lighter. The way these elements
are laid out on a page should create a feeling of balance.
There are two basic types of balance: symmetrical and asymmetrical. Symmetrical designs layout elements
of equal weight on either side of an imaginary center line. Asymmetrical balance uses elements of differing
weights, often laid out in relation to a line that is not centered within the overall design.
10. Morgan’s color code.
Color is one of the major contributors to the aesthetic appeal of the product. Many colors are linked with
different moods and conditions. Morgan has suggested the color code given in table.
Color Meaning
Red Danger, Hot
Orange Possible danger
Yellow Caution
Green Safe
Blue Cold

11. Ergonomic considerations
Definition: Ergonomics is the process of designing or arranging workplaces, products and systems so that
they fit the people who use them.
Ergonomics is the study of the interaction between people and machines and the factors that affect the
interaction. Its purpose is to improve the performance of systems by improving human machine interaction.
This can be done by ‘designing-in’ a better interface or by ‘designing-out’ factors in the work environment.
Principles of Ergonomics
a) Neutral Postures. The neutral posture refers to the human body aligned and balanced.
b) Reduce Excessive Force.
c) Keep Things Easy to Reach.
d) Work in Power or Comfort Zone.
e) Reduce Excessive Motion.
f) Reduce Static Load.
g) Minimize Pressure Points.
h) Provide Clearance.
12. Ergonomics relation between man, machine and environmental factors.
This is the system environment or what we call as working conditions. The proper integration of man and
machine, which is beneficial for human operator and enhances the overall system performance, is a primary
aim of the ergonomics discipline.
Characteristics of Man-machine System Are as follows:
(1) The man-machine system consists of the man, the machine and system environment.
(2) It is essentially artificial by nature and is specifically developed to fulfill some purpose or specific aim.
(3) It has specific inputs and outputs which are appropriately balanced.
(4) It is variable in size and complexity and is dynamic in performance.
(5) Subsystems of man machine system interact with and effects the other parts.
(6) The man-machine system becomes more efficient when inputs and out puts are adequately balanced.
(7) Environmental factors or system environment effects system performance. Environmental ergonomic
factors include things such as lighting, noise, and temperature.
13. Ergonomics Design of displays and controls.
General Guidelines for Designing the Display Devices:
(a) The display pointer should move in the same direction as the control itself i.e. a knob, hand wheel, lever,
crank etc. should revolve to the right to control the process, if the pointer of display moves to the right on a
circular scale.

(b) A clockwise turn of a control should mean an increase in the control process and anticlockwise turn should
mean decreased in flow.
(c) Concerned scales and knobs with a given specified function should be placed together. The best
arrangement would be scale above, knob below. All the display instruments and control instruments should
preferably be on the same control board. If the display panel is separate from the switch board, then the
arrangement of the knobs or switches must match that of the dials.
(d) The correct Symbols or icons must be specified at appropriate place wherever necessary.
General Guidelines for Designing the Controlling Devices
(a) Location of the controlling devices such as hand grips, levers, switches, dials, knobs, etc. is to be in such
a position that they are clearly and easily readable and comfortably and conveniently operable because any
manipulation of the machine deserves the full attention on these controlling devices.
(b) The designer should adhere to the principle of consistency of motion. For example, if turning increases
the input to the machine the knobs or head wheel clock wise, then the needle of the meter indicating the
reading of increase should also move clockwise.
(c) As far as possible the scales and knobs meant for the same function should be placed together. Two
methods are found to be most convenient in these designs are:
(i) Scales on upper side and controls down, and
(ii) Scales on left-hand side and controls on right hand side.
(d) The motion of pointer of the scale or dial should be consistent.
(e) The sub divisions and numerals on dials or scales should not strain the eyes and should clearly be visible
without causing much mental effort for reading.
(f) A control device should be marked with its function, indications of 'on' and 'off positions and the speed
levels or feed levels or steps of inputs, etc. If possible, it is better to use color codes or sound tones also so as
to make it distinctive.
(g) Shapes or alignment distinctions should be made wherever possible to avoid confusions. The computer
central processing unit (CPU) will have many points to be connected such as power cord, monitor connection,
mouse attachment, server connection, keyboard connection, etc. All these will have different shapes and
distinct in their pin positions by which one will not suit the other except in its correct point. Such designs will
enable the user to identify soon and be free from misalignments and confusions. Ergonomics
(h) Symbols and icons should be used for controls where ever possible. For example, each function on a
computer especially in Windows is now-a-days symbolized and kept as icons on menu bar, task bar to make
it user friendly.
(i) The control devices should be conventional and in the standard sizes which makes a new man also to
operate without any confusion and makes accident free. During late seventies and early eighties most of the
road accidents due to motor bikes have been registered due to confusion in break and gear control positions.

(j) The control positions should be designed in a logical sequence to prevent erroneous operations. If the
operations are sequential but of random in nature, it is preferable to discover the related group of functions so
that there is a set pattern of information, though there is no set pattern of operation. This enables the operator
to locate particular control readily.

2.0 DESIGN OF SHAFTS
Shaft is a common machine element which is used to transmit rotary motion or torque. It generally has circular
cross-section and can be solid or hollow. Shafts are supported on the bearings and transmit torque with the
help of gears, belts and pulleys etc. Shafts are generally subjected to bending moment, torsion and axial force
or a combination of these three. So the shafts are designed depending upon these conditions.
Shafts are designed on the basis of strength or rigidity or both. Design based on strength is to ensure that stress
at any location of the shaft does not exceed the material yield stress. Design based on rigidity is to ensure that
maximum deflection (because of bending) and maximum twist (due to torsion) of the shaft is within the
allowable limits.
In designing shafts on the basis of strength, the following cases may be considered:
(a) Shafts subjected to torque
(b) Shafts subjected to bending moment
(c) Shafts subjected to combination of torque and bending moment
(d) Shafts subjected to axial loads in addition to combination of torque and bending moment
2.1 Torsion of Shaft
Assumptions in Shear stress in a shaft subjected to torsion Strength and Rigidity
 The material is homogeneous (elastic property throughout)
 The material should follow Hook’s law
 The material should have shear stress proportional to shear strain
 The cross-sectional area should be plane
 The circular section should be circular
 Every diameter of the material should rotate through the same angle
 The stress of the material should not exceed the elastic limit
A shaft is said to be under pure torsion when it is subjected to two equal & opposite couples in a plane
perpendicular to the longitudinal axis of the shaft (i.e. twisting couples) in such a way that the magnitude of
twisting moment remains constant throughout the length of the shaft Its magnitude is given as the product of
the force and the distance between the forces. 𝑇𝑜𝑟𝑞𝑢𝑒, 𝑇 = 𝑃 × 𝑑
Fig.: Magnitude and representation of Torque

The figure shows a bar or shaft of circular section, subjected to torque T. Such a case is a case of pure
torsion,
Fig.: Shaft is under pure torsion
where
 T = torque or twisting moment, [N×m]
 J = polar moment of inertia or polar second moment of area about shaft axis, [m4
]
 τ = shear stress at outer fiber, [Pa]
 r = radius of the shaft, [m]
 G = modulus of rigidity or shear modulus [Pa]
 θ = angle of twist, [rad]
 L = length of the shaft, [m]
𝝉
𝑹
=
𝑻
𝑱
=
𝑮𝜽
𝑳
The shear modulus (G) is the ratio of shear stress to shear strain. Like the modulus of elasticity, the shear
modulus is governed by Hooke’s Law: the relationship between shear stress and shear strain is proportional
up to the proportional limit of the material.
𝑮 =
𝝉
𝜸
=
𝑻. 𝑳
𝑱. 𝜽
𝑱/𝑹 is known as torsional section modulus., & 𝑮. 𝑱 is known as torsional rigidity of the bar or the shaft.
The above relation states that the intensity of shear stress at any point in the cross-section of a shaft subjected
to pure torsion is proportional to its distance from the center and the variation of shear stress with respect to
radial distance is linear.
2.2 Polar moment of inertia (J)
solid shaft hollow circular shaft
𝐽 =
𝜋 𝑅4
2
=
𝜋 [
𝐷
2
]
4
2
=
𝜋 𝐷4
32
𝐽 =
𝜋 [𝐷4
− 𝑑4]
32
2.3 Torsional rigidity

Torsional stiffness or torsional rigidity is a measure of the amount of torque required to twist one unit length
of an object by one unit radian.
Torsional rigidity is the product of shear modulus (G) and polar moment of inertia (J). The torsional rigidity
shows the resistance offered by a material to angular deformation.
Torsional rigidity is also defined as the torque required to produce a unit radian angle of twist per unit length
of the shaft. The term torsional rigidity is expressed as,
Torsional rigidity = G x J
we know that Torsional equation is
𝜏
𝑅
=
𝑇
𝐽
=
𝐺𝜃
𝐿
Thus the equation of torsional rigidity can also be written as,
𝑇
𝐽
=
𝐺𝜃
𝐿
≫ 𝑮. 𝑱 =
𝑻𝑳
𝑱𝜽
… … N. m²
Where,
L = Length of shaft (mm)
T = Torque (N.m)
θ = Angle of Twist (Radians)
2.4 Torsional Strength (Shafts Subjected to Torque)
Measure of the ability of a material to withstand a twisting load. It is the ultimate strength of a material
subjected to torsional loading, and is the maximum torsional stress that a material sustains before rupture.
Alternate terms are modulus of rupture and shear strength.
When a shaft is subjected to a torque or twisting a shearing stress is produced in the shaft. The shear stress
varies from zero in the axis to a maximum at the outside surface of the shaft. The shear stress in a solid circular
shaft in a given position can be expressed as:
𝑇
𝐽
=
𝜏
𝑅
≫ 𝝉 =
𝑻. 𝑹
𝑱
Where
τ = shear stress (Pa, lbf/ft2 (psf))
T = twisting moment (Nm, lbf ft)
r = distance from center to stressed surface in the given position (m, ft)
J = Polar Moment of Inertia of Area (m4, ft4)

2.5 Torsional Deflection of Shaft
The angular deflection of a torsion shaft can be expressed as
𝜽 =
𝑳. 𝑻
𝑱. 𝑮
Where
θ= angular shaft deflection (radians)
L = length of shaft (m)
G = modulus of rigidity or shear modulus [Pa]
The angular deflection of a torsion solid shaft can be expressed as
𝜽 =
𝟑𝟐. 𝑳. 𝑻
𝝅. 𝑫𝟒. 𝑮
The angular deflection of a torsion hollow shaft can be expressed as
𝜽 =
𝟑𝟐. 𝑳. 𝑻
𝝅. (𝑫𝟒 − 𝒅𝟒). 𝑮
2.6 Power Transmitted (P)
Let us consider a circular shaft running at N rpm under mean torque T. Let P be the power transmitted by
the shaft in kW. The angular speed of the shaft is given by the distance covered by a particle in the circle in
radians for N revolutions per second, i.e. the particle covers  radians for one revolution and for N
revolutions the particle covers 2N radians in one minute. Hence the angular speed  is given by:
 =
2πNR
60
… … … … 𝑟𝑎𝑑/𝑠
Thus, the 𝒑𝒐𝒘𝒆𝒓 𝒕𝒓𝒂𝒏𝒔𝒎𝒊𝒕𝒕𝒆𝒅 = 𝑴𝒆𝒂𝒏 𝒕𝒐𝒓𝒒𝒖𝒆 (𝒌𝑵 − 𝒎) 𝒙 𝑨𝒏𝒈𝒖𝒍𝒂𝒓 𝒔𝒑𝒆𝒆𝒅 (𝒓𝒂𝒅/𝒔)
𝑷 = 𝐓 =
𝟐𝝅𝑵𝑻
𝟔𝟎
… … … … … . 𝑘𝑁 − 𝑚 𝑜𝑟 𝑘𝑊
It is seen that from the above equation mean torque T in kN-m is obtained. It should be converted to N-mm
so that the stress due to torque can be obtained in N/mm2
. Maximum shear stress due to torque can be
obtained from the torque equation.
𝝉
𝑹
=
𝑻
𝑱
=
𝑮𝜽
𝑳

2.7 Design of Shafts
The shafts may be designed on the basis of
1. Strength
Design based on strength is to ensure that stress at any location of the shaft does not exceed the material yield
stress.
Maximum shear stress developed in a shaft subjected to torque is given by,
𝝉 =
𝑻. 𝑹
𝑱
≤ 𝜏 𝑦𝑒𝑖𝑙𝑑(𝑀𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑌𝑒𝑖𝑙𝑑 𝑠𝑡𝑟𝑒𝑠𝑠)
Where
T = Twisting moment (or torque) acting upon the shaft,
J = Polar moment of inertia of the shaft about the axis of rotation
=
𝜋 𝐷4
32
for solid shafts with diameter d
=
𝜋 [𝐷4−𝑑4]
32
for hollow shafts with D and d as outer and inner diameter.
R = Distance from neutral axis to the outer most fiber = d/2 (or do/2)
So dimensions of the shaft subjected to torque can be determined from above relation for a known value of
allowable shear stress, [τ].
2. Rigidity and stiffness
Design based on rigidity is to ensure that maximum deflection (because of bending) and maximum twist (due
to torsion) of the shaft is within the allowable limits.
Torsional Rigidity
For a shaft subjected twisting moment, the angle of twist is given by,
𝜽 =
𝑳. 𝑻
𝑱. 𝑮
≤ 𝜃𝑑
Where,
T = Torque applied
L = Length of the shaft
J = Polar moment of inertia of the shaft about the axis of rotation
G = Modulus of rigidity of the shaft material
Therefore for the known values of T, L and G and allowable value of angle of twist, diameter of the shaft can
be calculated.
Lateral Rigidity
Bending moment acting on any shaft is given by,
𝑴 = 𝐄. 𝐈.
𝒅𝟐
𝒚
𝒅𝒙𝟐

Integrating this equation twice with respect to x and applying the boundary conditions, y can be calculated. y
should be ≤ allowable value of deflection, [y].
In designing shafts on the basis of strength, the following cases may be considered:
(a) Shafts subjected to twisting moment or torque only,
𝜏 =
𝑇. 𝑅
𝐽
=
𝑇.
𝐷
2
𝜋 𝐷4
32
=
16. 𝑇
𝜋. 𝐷3
(b) Shafts subjected to bending moment only,
Maximum bending stress developed in a shaft is given by,
𝝈 𝒃 =
𝑴. 𝐲
𝑰
≤ 𝜎𝑡
Where
M = Bending Moment acting upon the shaft,
I = Moment of inertia of cross-sectional area of the shaft about the axis of rotation
=
𝜋 𝐷4
64
for solid shafts with diameter d
=
𝜋 [𝐷4−𝑑4]
64
for hollow shafts with D and d as outer and inner diameter.
y = Distance from neutral axis to the outer most fibre = d / 2 (or do/2)
So dimensions of the shaft subjected to bending moment can be determined from above relation for a
known value of allowable tensile stress, [τ].
𝜎𝑏 =
𝑀. 𝑦
𝐼
=
𝑀.
𝐷
2
𝜋 𝐷4
64
=
32. 𝑀
𝜋. 𝐷3
(c) Shafts subjected to combined twisting and bending moments
When the shaft is subjected to combination of torque and bending moment, principal stresses are calculated
and then different theories of failure are used. Bending stress and torsional shear stress can be calculated using
the above relations.
Maximum Shear Stress Theory
Maximum shear stress is given by, 𝜏 𝑚𝑎𝑥 = √(
𝐵𝑒𝑛𝑑𝑖𝑛𝑔 𝑀𝑜𝑚𝑒𝑛𝑡
2
)
2
+ (Maximum shear stress)2
𝝉 𝒎𝒂𝒙 = √(
𝜎𝑏
2
)
2
+ (𝜏)2 = √(
32. 𝑀
𝜋. 𝐷3
2
)
2
+ (
16. 𝑇
𝜋. 𝐷3
)
2
= √(
16. 𝑀
𝜋. 𝐷3
)
2
+ (
16. 𝑇
𝜋. 𝐷3
)
2
=
𝟏𝟔
𝝅. 𝑫𝟑
√𝑴𝟐 + 𝑻𝟐 ≤ 𝜏 𝑦
√𝑀2 + 𝑇2 is called equivalent torque, Te, such that 𝜏 𝑚𝑎𝑥 =
𝑇𝑒.𝑅
𝐽
≤ 𝜏 𝑦𝑒𝑖𝑙𝑑

Maximum Principal Stress Theory
Maximum principal stress is given by,
𝜎 =
2
+ √(
2
)
2
+ (Maximum shear stress)2
𝜎 =
𝜎𝑏
2
+ √(
𝜎𝑏
2
)
2
+ (𝜏)2 =
32. 𝑀
𝜋. 𝐷3
2
+ √(
32. 𝑀
𝜋. 𝐷3
2
)
2
+ (
16. 𝑇
𝜋. 𝐷3
)
2
=
16. 𝑀
𝜋. 𝐷3
+ √(
16. 𝑀
𝜋. 𝐷3
)
2
+ (
16. 𝑇
𝜋. 𝐷3
)
2
∴ 𝝈 =
𝟏𝟔
𝝅. 𝑫𝟑
[𝑴 + √(𝑴)𝟐 + (𝑻)𝟐] ≤ 𝜎𝑡
[𝑀 + √(𝑀)2 + (𝑇)2] is called equivalent bending moment, Me, such that 𝜎𝑏 =
𝑀.𝑦
𝐼
≤ 𝜎𝑡
(d) Shafts subjected to axial loads in addition to combined torsional and bending loads.
Tensile Stress due to axial load is given by,
𝜎𝑡 =
𝑃
𝐴
Where,
P = axial load acting on the shaft
A= cross-sectional area of the shaft
As nature of the bending stress and this axial stress is same, these can be added for any location on the shaft,
so as to get the resultant tensile/compressive stress, which can then be used to find the principal stresses in the
shaft.
2.8 Power Transmitted by Solid and Hollow shaft
Solid Shaft Hallow Shaft
𝑁𝑜𝑡𝑒: 𝑪 =
𝒅
𝑫
𝜏
𝑅
=
𝑇
𝐽
≫ 𝜏 =
𝑇. 𝑅
𝐽
=
𝑇.
𝐷
2
𝐽
≫ 𝝉 =
𝑻. 𝑫
𝟐. 𝑱
𝜏
𝑅
=
𝑇
𝐽
≫ 𝜏 =
𝑇. 𝑅
𝐽
=
𝑇.
𝐷
2
𝐽
≫ 𝝉 =
𝑻. 𝑫
𝟐. 𝑱
𝐽 =
𝜋 𝐷4
32
𝐽 =
𝜋 [𝐷4
− 𝑑4]
32
=
𝜋 𝐷4
. [1 −
𝑑4
𝐷4]
32
=
𝜋 𝐷4
. [1 − 𝐶4]
32

𝜏 =
𝑇. 𝐷
2. 𝐽
=
𝑇. 𝐷
2. (
𝜋 𝐷4
32
)
=
𝑇. 𝐷
𝜋 𝐷4
16
𝜏 =
𝑇. 𝐷
2. 𝐽
=
𝑇. 𝐷
2. (
𝜋 𝐷4. [1 − 𝐶4]
32
)
=
𝑇. 𝐷
𝜋 𝐷4. [1 − 𝐶4]
16
𝑇 =
𝜏. (
𝜋 𝐷4
16
)
𝐷
= 𝜏. (
𝜋 𝐷4
𝐷. 16
) ∴ 𝑻 = 𝝉. (
𝝅 𝑫𝟑
𝟏𝟔
) 𝑇 =
𝜏.
𝜋 𝐷4
. [1 − 𝐶4]
16
𝐷
∴ 𝑻 = 𝝉.
𝝅 𝑫𝟑
. [𝟏 − 𝑪𝟒]
𝟏𝟔
𝑷 = 𝐓 =
𝟐𝝅𝑵𝑻
𝟔𝟎
𝑷 = 𝐓 =
𝟐𝝅𝑵𝑻
𝟔𝟎
𝑷𝑺𝒐𝒍𝒊𝒅 = 𝝉. (
𝝅 𝑫𝟑
𝟏𝟔
) .  𝑷𝑯𝒐𝒍𝒍𝒐𝒘 = 𝝉.
𝝅 𝑫𝟑
. [𝟏 − 𝑪𝟒]
𝟏𝟔
. 
Case 1: If outer diameter of solid and Hollow shaft are of same diameter and same material and length.
𝑷𝑺𝒐𝒍𝒊𝒅
𝑷𝑯𝒐𝒍𝒍𝒐𝒘
=
𝜏. (
𝜋 𝐷3
16
) . 
𝜏.
𝜋 𝐷3. [1 − 𝐶4]
16
. 
=
𝟏
𝟏 − 𝑪𝟒
𝑑
𝐷
is always less than 1, that is 𝐂 < 𝟏 ∴
𝟏
𝟏 − 𝑪𝟒
> 𝟏 ∴ 𝑷𝑺𝒐𝒍𝒊𝒅 > 𝑷𝑯𝒐𝒍𝒍𝒐𝒘
Case 2: If Area of cross section of solid and Hollow shaft are of same diameter and same material and
length.
𝑷𝑺𝒐𝒍𝒊𝒅 = 𝝉. (
𝝅 𝒅𝟑
𝟏𝟔
) .  𝑷𝑯𝒐𝒍𝒍𝒐𝒘 = 𝝉.
𝝅 𝑫𝟑
. [𝟏 − 𝑪𝟒]
𝟏𝟔
. 
=
𝜏. (
𝜋 𝑑3
16
) . 
𝜏.
𝜋 𝐷3. [1 − 𝐶4]
16
. 
=
𝒅𝟑
𝑫𝟑
𝟏
(𝟏 − 𝑪𝟒)
… … … 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝟏
𝑾𝒆𝒊𝒈𝒉𝒕 = 𝒎𝒂𝒔𝒔 × 𝒈
= 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 × 𝒗𝒐𝒍𝒖𝒎𝒆 × 𝒈
∴ 𝑾𝒆𝒊𝒈𝒉𝒕 = 𝒅𝒆𝒏𝒔𝒊𝒕𝒚 × 𝒂𝒓𝒆𝒂 × 𝒍𝒆𝒏𝒈𝒕𝒉 × 𝒈 = 𝒂𝒓𝒆𝒂 × 𝒍 × 𝝆 × 𝒈
(𝑾𝒆𝒊𝒈𝒉𝒕)𝑺𝒐𝒊𝒍𝒅 = (𝑾𝒆𝒊𝒈𝒉𝒕)𝑯𝒐𝒍𝒍𝒐𝒘
𝝅 𝒅𝟐
𝟒
× 𝒍 × 𝝆 × 𝒈 =
𝝅 [𝑫𝟐
− 𝒅𝟐]
𝟒
× 𝒍 × 𝝆 × 𝒈
𝒅𝟐
= [𝑫𝟐
− 𝒅𝟐] = 𝑫𝟐
[𝟏 −
𝒅𝟐
𝑫𝟐
] = 𝑫𝟐[𝟏 − 𝑪𝟐]

𝒅𝟐
𝑫𝟐
= [𝟏 − 𝑪𝟐]
∴
𝒅
𝑫
= √[𝟏 − 𝑪𝟐] … … … . 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝟐
𝒔𝒖𝒃𝒔𝒕𝒊𝒕𝒖𝒕𝒊𝒏𝒈 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝟐 𝒘𝒆 𝒈𝒆𝒕
=
𝒅𝟑
𝑫𝟑
.
𝟏
(𝟏 − 𝑪𝟒)
= (√[𝟏 − 𝑪𝟐])
𝟑
.
𝟏
(𝟏 − 𝑪𝟒)
= (√[𝟏 − 𝑪𝟐])
𝟑
.
𝟏
(𝟏 − 𝑪𝟒)
=
[𝟏 − 𝑪𝟐]
𝟑
𝟐
(𝟏 − 𝑪𝟒)
=
[𝟏 − 𝑪𝟐]
𝟏
𝟐 × [𝟏 − 𝑪𝟐]
[𝟏 + 𝑪𝟐] × [𝟏 − 𝑪𝟐]
=
[𝟏 − 𝑪𝟐]
𝟏
𝟐
[𝟏 + 𝑪𝟐]
=
√[𝟏 − 𝑪𝟐]
[𝟏 + 𝑪𝟐]
∴
=
√[𝟏 − 𝑪𝟐]
[𝟏 + 𝑪𝟐]
𝒇𝒐𝒓 𝑪 < 𝟏, 𝒘𝒆 𝒈𝒆𝒕 [𝟏 + 𝑪𝟐] > √[𝟏 − 𝑪𝟐] ∴ 𝑷𝑯𝒐𝒍𝒍𝒐𝒘 > 𝑷𝑺𝒐𝒍𝒊𝒅
2.9 A.S.M.E. Code for Shaft Design
According to (American Society for Mechanical Engineering) A.S.M.E. code, the bending and twisting
moment are to be multiplied by factors kb and kt respectively, to account for shock and fatigue in operating
condition. Therefore, if the shaft is subjected to dynamic loading, equivalent torque and equivalent bending
moment will become:
𝑻𝒆 = √𝒌𝒃 𝑴𝟐 + 𝒌𝒕 𝑻𝟐 𝒂𝒏𝒅 𝑴𝒆 = 𝒌𝒃 𝑴 + √𝒌𝒃 𝑴𝟐 + 𝒌𝒕 𝑻𝟐
Values of 𝑘𝑏 and 𝑘𝑡 for different types of loading
𝑘𝑏 𝑘𝑡
Gradually applied load 1.5 1.0
Suddenly applied load (minor shock) 1.5 ~ 2.0 1.0 ~ 1.5
Suddenly applied load 2.0 ~ 3.0 1.5 ~ 3.0
2.10 BIS Code for Shaft Design
Transmissible torques
The values of transmissible torques have been calculated from the following formulae and rounded off to
normal numbers of the exceptional R 80 series (l):
a) Transmission of pure torque:

𝑇 =
𝜋
4
× 10−3
× 𝑑1
3
(𝑘𝑔𝑓 − 𝑚) 𝑜𝑟 𝑻 =
𝝅 × 𝟗. 𝟖𝟎𝟔𝟔𝟓
𝟒
× 𝟏𝟎−𝟑
× 𝒅𝟏
𝟑
(𝑵 − 𝒎)
This torque corresponds to a stress of 4 kgf/mm2. In case of reversal of rotation fluctuations, of high or
irregular torque, or of high bending and deformation moments in the coupling, the stresses will have to be
checked by appropriate means.
b) Transmission of torque and bending moment both of c known size:
𝑇 = 6 × 10−5
× 𝑑1
3.5
(𝑘𝑔𝑓 − 𝑚) 𝑜𝑟 𝑻 = 𝟓𝟖. 𝟖𝟑𝟗𝟗 × 𝟏𝟎−𝟓
× 𝒅𝟏
𝟑.𝟓
(𝑵 − 𝒎)
This formula may be applied subject to checking when the torque and bending moment are disproportionate
in their influence.
c) Transmission both of a known torque and of an undetermined bending moment:
𝑇 = 2.8 × 10−5
× 𝑑1
3.5
(𝑘𝑔𝑓 − 𝑚) 𝑜𝑟 𝑻 = 𝟐𝟕. 𝟒𝟓𝟖𝟔𝟐 × 𝟏𝟎−𝟓
× 𝒅𝟏
𝟑.𝟓
(𝑵 − 𝒎)
This formula is applicable to the dimensioning of shaft ends of primary machines (for example, electric
motors, pumps, etc.) of general manufacture and capable of meeting all conditions of usage.
NOTE. - The three formulae assume the use of steel having a tensile strength of 50 to 60 kgf/mm2
.

3.0 Springs
Spring is a mechanical component which stores mechanical energy when force is applied and release that
energy when the load is removed. Spring goes back to its original shape when the load is removed. Springs
are mainly used for
1. To absorb shock
2. To reduce friction and vibration
3. To store energy and release when required
4. To ease in locking, pivoting, holding, etc
3.1 Classification of springs
Below is the list of different types of springs that most of the industry uses. The main types of springs which
are further categorized into different subcategories. Based on the shape of the springs, it can be broadly
classified into following types:
1. Helical Spring
2. Leaf Springs
3. Belleville spring
4. Volute and conical spring
5. Special purpose spring
3.2. Helical Spring:
It is the most commonly used Mechanical springs. In this type of spring a coil is wrapped in such a way that
it resemble like a thread. This type of springs is used for carrying Compression, Extension, and Torque forces.
According to the loading condition helical springs are classified into following four types.
 Closed coil springs (or) Tension helical springs
 Open coil springs (or) Compression helical springs
 Torsion spring
 Spiral spring
a.) Tension spring:
Tension Springs are also called as Extension Springs. Tension spring is opposite to compression spring. Pull
force is applied, resulting in extension of the spring. These type of springs have hook or expanded eyes either
one or both ends
Applications:
 Lever mechanisms
 Counterbalancing of garage doors
 Weighing machine,
 Vise-grip pilers
 Garage door assemblies
b.) Compression spring:

These springs are open coil helical spring. A helical coil is pressed or squeezes by load. It resists compressive
or push forces. It also shows resistance to linear compressive forces. Sometimes fluid behave as compression
springs such as fluid pressure systems.
Application:
 Motorcycle’s suspensions.
 Pen
 Lock
 Couches
 Lighter
c.) Torsion spring
In this type of spring the load applied to coil is a torque or twisting force. In other words, Helical springs
which can hold and release angular energy. Or these springs try to hold a system in place. After twisting, the
helical coil applies proportional force to opposite direction. The torsion springs are used in application which
rotates Less than 360 degree. These springs have either clockwise or antilock wise rotation.
Applications:
 Mouse trap
 Rocker switches
 Clothes pin
 Automobile starters
 Door hinges
d.) Spiral Springs
Spiral spring is also known as clock spring or Constant force spring. A number of times band of steel wrapped
around it to form this type of springs. This type of springs releases a constant amount of force. This types of
springs are used in machines that need to rotate a number of times and the same time has to release same
amount of load constantly. These types of springs are used when more power is required. Some of these
springs are with thicker bond so that they can give fever rotations. These types of springs are used in heavy
duty applications
Applications:
 Automotive seat recliners
 Alarm timepiece
 Watch
 Window Regulators
 DC Motors

3.3 Leaf springs
Leaf springs are also called as s semi- elliptical spring or Cart spring. It is one of the oldest forms of springs.
Leaf springs are long and flat slender arc -shaped. These types of springs are used In Vehicle suspensions.
Location for axel is center of the arc. And either end of loop is attached to the vehicle. It spread the load over
vehicle chassis.
Advantages
 Leaf springs are easy to construct.
 These springs are strong.
 No need for separate linkage to hold the axle in
position, leaf springs work as a linkage.
 Rear axle location helps in reducing the extra weight.
 Axle damping is control by leaf springs.
 It reduces cost by eliminating the need of trailing arm and pan hard rod.
Applications:
 Automobiles Suspension
 Used by blacksmiths (due to its relatively high quality steel.)
3.4 Belleville spring
A Belleville springs also known as a coned-disc spring, conical spring washer, disc spring, Belleville washer
or cupped spring washer. Belleville washers are mostly coin shape spring with a hole in center. This disc
springs are dynamically or statically loaded to its axis. This spring required less space for installation but can
bear a very large load. These springs have more advantages compare to other springs.
Applications:
 Slip Clutch
 Overload Clutches
 High Pressure Valve
 Drill Bit Shock Absorber
3.5 Volute and conical spring
These springs are conical shape compression springs. Conical springs are
also known as tapered spring. These springs used to provide stability and
reduce solid height.
3.6 Special purpose spring:
As the name suggest this springs are made for special purpose use.
Special purpose springs are made up from different types of material all together such as Air and water.
Other types of springs are:
1. Constant Spring 4. Flat Spring 7. Cantilever Springs 10. Gas Spring
2. Variable Spring 5. Machined Spring 8. Hairspring or Balance Spring 11. Ideal Spring
3. Variable Stiffness Spring 6. Serpentine Spring 9. V-Spring 12. Main Spring

3.7 Application of springs
 To store energy and release when required.
 To return a component to the original position after the load is withdrawn.
 To reduce shock, impact, and vibration among moving parts
 Reduce the effect of impact loading
 Control the motion as in the case with CAM and follower
 To maintain electrical continuity
 To counterbalance weight
3.8 Materials of springs
The below list shows common materials used for spring manufacturing. Those are either converted to wire
form or strip form before coiled into a spring.
 Stainless steel
 Alloy steel
 Titanium
 Phosphor Bronze
 High carbon spring wire ( Hard drawn)
 Beryllium copper
The material used to made springs are called a spring steel. Spring steels are mostly low-alloy manganese,
low carbon steel or high carbon steel with very high yield strength. Examples of spring materials are as
follows:
1. Oil Tempered Steel
2. Stainless Steel
3. Carbon Value
4. Monel
5. Titanium
6. Chrome Silicon
3.9 Specification of springs
Specifications for Compression Springs
 Free Length, Maximum, Minimum.
 Controlling Diameter, Outside Diameter
Maximum, Inside Diameter Minimum,
Pitch Diameter, Works inside (Dia. Hole),
Works Over (Dia. Shaft).
 Number of Coils

 Wire Size. Decimal size if possible.
 Material, Kind and Grade.
 Loads at deflected positions.
 Style of Ends, (see illustrations).
 Right or Left Hand Wound.
 Finish. Plain unless otherwise specified.
 Maximum Solid Length.
 Frequency of Compression.
3.10 Specifications for Torsion Springs
 Inside or Outside Diameter.
 If spring works on a rod, give size of same, as spring must not bind when wound up to its limit of
travel.
 Free length and number of coils. If spring cannot increase in length as wound up,
allow sufficient space between coils.
 Wire Size. Decimal size if possible.
 Style of Ends, (see illustrations).
 Number of turn’s deflection to hold given load and radius of loaded arm. This length may be the
length of the arm, or the arm may be attached to a movable machine member, in which case the
length to point of application of load is given.
 Finish, Plain unless otherwise specified.
3.11 Specifications for Extension Springs
 Length, Maximum, Minimum, (Overall, Over coil, Inside Hooks).
 Controlling Diameter: Outside Diameter Maximum. Inside Diameter Minimum.
 Wire Size. Decimal size if Possible.
 Number of Coils.
 Style of Ends (see
illustrations)
 Finish (Plain unless otherwise specified).
 Load Required, Length Inside-Hooks (Length of Coil if wire size not specified).
 Maximum Extended Length (Overall, over coil, Inside Hooks).
 Deflection or Distance of Travel.

 Frequency of Extension.
3.12 Terminology of Helical spring
The following are the terms used for helical spring:
1. Solid length
2. Free length
3. Mean diameter
4. Pitch
5. Spring index
6. Helix angle of spring
1. Solid length
When all the coils of the spring are compressed such that they come in contact
with each other than the length of the spring is said to be the solid length.
Mathematically, Solid length = Total no. of coils × spring wire diameter (d)
2. Free length (Lo)
The free length of the helical spring is the length of the spring in an unloaded or free condition.
3. Mean diameter (D)
The mean diameter of the helical spring is the average of the outer coil diameter (De) and the inner coil
diameter (Di ).
Mathematically, Mean diameter (D) = (De + Di ) / 2
4. Pitch (P)
The pitch of the spring is defined as the axial distance between two adjacent coils in unloaded condition.
5. Spring Index (C)
Spring index of helical spring is defined as the ratio of the mean diameter of spring (D) to the spring wire
diameter (d)
Mathematically we can say, Spring Index (C) = D / d
6. Helix angle of spring (α)
The helix angle of the helical spring is the angle made by the spring wire axis and a line perpendicular to the
axis of the spring as shown in the above figure.

3.13 Design of helical spring
Let
P = axial load, N
D = mean diameter of coil, mm
d = diameter of wire, mm
p = pitch of coils, mm
δ = deflection of spring, mm
n = number of active coils
C = spring index = D/d = (Do-d)/d
(4: 12); It is because that less than 4 it is difficult to manufacture, more than 12 is likely to buckle.
G = torsional modulus of elasticity, N/mm2
τs = shearing stress, N/mm2
3.14 General Design consideration for solid circle cross section
The torque equation is equals to
𝑇 =
𝑃. 𝐷
2
The shearing stress due to the torque T is
𝝉𝑻 =
𝑇. 𝑅
𝐽
=
𝟖. 𝑷. 𝑫
𝝅. 𝒅𝟑
𝑎𝑠 𝐽 =
𝜋. 𝑑4
32
Direct shearing stress is
𝝉𝑫 =
𝑃
𝐴
=
𝟒. 𝑷
𝝅. 𝒅𝟐
𝑎𝑠 𝐴 =
𝜋. 𝑑2
4
𝑴𝒂𝒙𝒊𝒎𝒖𝒎 𝒔𝒉𝒆𝒂𝒓𝒊𝒏𝒈 𝒔𝒕𝒓𝒆𝒔𝒔 = 𝒔𝒉𝒆𝒂𝒓𝒊𝒏𝒈 𝒔𝒕𝒓𝒆𝒔𝒔 𝒅𝒖𝒆 𝒕𝒐 𝒕𝒉𝒆 𝒕𝒐𝒓𝒒𝒖𝒆 + 𝑫𝒊𝒓𝒆𝒄𝒕 𝒔𝒉𝒆𝒂𝒓𝒊𝒏𝒈 𝒔𝒕𝒓𝒆𝒔𝒔
𝝉𝒎𝒂𝒙 = 𝝉𝑻 + 𝝉𝑫
𝜏𝑚𝑎𝑥 =
8. 𝑃. 𝐷
𝜋. 𝑑3
+
4. 𝑃
𝜋. 𝑑2
=
8. 𝑃. 𝐷
𝜋. 𝑑3
[1 +
1
2. 𝐶
]
𝝉𝒎𝒂𝒙 =
𝟖. 𝑷. 𝑫
𝝅. 𝒅𝟑
[𝟏 +
𝟏
𝟐. 𝑪
]
Where [𝟏 +
𝟏
𝟐.𝑪
] is the direct shear factor.
In order to include the effects of both direct shear and wire curvature, a stress factor had been determined by
the use of approximate analytical methods by A. M. Wahl which may be used in the above equation to
determine the maximum shearing stress in the wire as follows:
𝝉𝒎𝒂𝒙 = 𝑲𝒘
𝟖. 𝑷. 𝑫
𝝅. 𝒅𝟑
= 𝑲𝒘
𝟖. 𝑷. 𝑪
𝝅. 𝒅𝟐

𝒅 = √
𝟖. 𝑲𝒘. 𝑷. 𝑪
𝝅. 𝝉𝒎𝒂𝒙
Where
𝑲𝒘 =
𝟒𝑪 − 𝟏
𝟒𝑪 − 𝟒
+
𝟎. 𝟔𝟏𝟓
𝑪
Deflection equation (δ) may be obtain
𝑷. 𝜹
𝟐
=
𝑇. 𝜃
2
=
𝑻
𝟐
. (
𝑻. 𝑳
𝑮. 𝑳
) 𝑎𝑠 θ =
T. L
G. J
Where
𝑇 =
𝑃. 𝐷
2
𝐿 = 𝜋. 𝐷. 𝑛
𝐽 =
𝜋. 𝑑4
32
δ =
2
𝑃
×
𝑇
2
× (
𝑇. 𝐿
𝐺. 𝐿
) =
𝑇2
. 𝐿
𝑃. 𝐺. 𝐽
=
(
𝑃. 𝐷
2
)
2
(𝜋. 𝐷. 𝑛)
𝑃. 𝐺. (
𝜋. 𝑑4
32
)
=
8. 𝑃. 𝐷3
. 𝑛
𝐺. 𝑑4
𝛅 =
𝟖. 𝑷. 𝑫𝟑
. 𝒏
𝑮. 𝒅𝟒
=
𝟖. 𝑷. 𝑪𝟑
. 𝒏
𝑮. 𝒅
(P/δ) is known as the spring rate.
(
𝐏
𝛅
) =
𝑮. 𝒅
𝟖. 𝑪𝟑. 𝒏
3.15 Spring ends:
For helical springs may either plain, plain ground, square, or squared and ground as shown in Figure below.
This results in a decrease of the number of active coils and affects the tree length and solid length of the spring
as shown below.
P= (D/3: D/4), n= (3: 15)

3.16 Buckling:
Buckling may occur in compression springs if the free length is over 4 times the mean diameter unless the
spring is properly guided. The critical axial load that will cause buckling may be approximated by
𝐹
𝑐𝑟 = 𝑘. 𝐿𝑓 . 𝐾𝐿
Where:
𝐹
𝑐𝑟 = 𝑎𝑥𝑖𝑎𝑙 𝑙𝑜𝑎𝑑 𝑡𝑜 𝑝𝑟𝑜𝑑𝑢𝑐𝑒 𝑏𝑢𝑐𝑘𝑙𝑖𝑛𝑔, 𝑁
𝑘 = 𝑠𝑝𝑟𝑖𝑛𝑔 𝑟𝑎𝑡𝑒, 𝑁/𝑚, 𝑜𝑓 𝑎𝑥𝑖𝑎𝑙 𝑑𝑒𝑓𝑙𝑒𝑐𝑡𝑖𝑜𝑛
𝐿𝑓 = 𝑓𝑟𝑒𝑒 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝𝑟𝑖𝑛𝑔, 𝑚
𝐾𝐿 = 𝑎 𝑓𝑎𝑐𝑡𝑜𝑟 𝑑𝑒𝑝𝑒𝑛𝑑𝑖𝑛𝑔 𝑜𝑛 𝑡ℎ𝑒 𝑟𝑎𝑡𝑖𝑜 𝐿𝑓/𝐷
Or 𝐿𝑓/𝐷 < 3 for no buckling and Buckling depends mainly on
𝐿𝑓/𝐷 and 𝛿/𝐿𝑓
3.17 General Design Features:
 𝑆𝑜𝑙𝑖𝑑 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝𝑟𝑖𝑛𝑔 𝐿𝑠 = 𝑛. 𝑑
 𝐹𝑟𝑒𝑒 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝𝑟𝑖𝑛𝑔 𝐿𝐹 = 𝑛. 𝑑 + 𝛿 + 0.15. 𝛿
 𝑇ℎ𝑒 𝑃𝑖𝑡𝑐ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝𝑟𝑖𝑛𝑔 𝑃 =
𝐿𝐹
𝑛−1
 𝑂𝑢𝑡𝑒𝑟 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑠𝑝𝑟𝑖𝑛𝑔 𝐷𝑜 = 𝐷 + 𝑑
 𝐼𝑛𝑛𝑒𝑟 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝𝑟𝑖𝑛𝑔 𝐷𝑖 = 𝐷 − 𝑑

4. Design of Coupling
4.1 Design of Sleeve or Muff Coupling
Assembly of muff coupling is shown in Figure below. Sleeve, a hollow cylinder, is fitted on the ends of input
and output shaft with the help of a sunk key. Torque is transmitted from input shaft to the sleeve through key
and from the sleeve to the output shaft through the key again. It is simple to design and manufacture but
difficult to assemble and dismantle. It requires more axial space and has small radial dimensions. Sleeve is
made of cast iron and for it a larger factor of safety of 6-8 is used on the ultimate strength. Standard proportions
used for sleeve are three main components: shafts, sleeve and key.
4.2 Design Procedure
Step 1. Design of Shaft. (d)
Generally power transmitted by shaft is given, hence first of all find torque transmitted by shaft as
𝑷 =
𝟐𝝅𝑵𝑻
𝟔𝟎
For the given Power output (P) and revolution in rpm (N) identify the required Torque (T) in N-
mm, Now as per torsion equation,
𝜏 =
𝑇. 𝑅
𝐽
=
𝑇.
𝐷
2
𝜋 𝐷4
32
=
16. 𝑇
𝜋. 𝐷3
≫ 𝑻 =
𝟏𝟔
𝝅
× 𝝉 × 𝒅𝟑
∴ 𝒅 = √
𝑻
𝝉
×
𝝅
𝟏𝟔
𝟑
Step 2. Proportions of sleeve.
The usual proportions of a cast iron sleeve coupling are as follows
Outer diameter of the sleeve, D = 2 d + 13 mm and length of the sleeve, L = 3.5 d
Where, d is the diameter of the shaft.
Step 3. Design of Key
a) The usual proportions for rectangular key are
Width of key, w = d/4, and thickness of key, t = d/6
Where, d = Diameter of the shaft or diameter of the hole in the hub.
b) The usual proportions for square key proportions are
Width of key, w = d/4, and thickness of key, t = d/4
Where, d = Diameter of the shaft or diameter of the hole in the hub.

4.3 Design of Flange coupling
Flange coupling consists of two flanges keyed to the shafts. The flanges are connected together by means of
bolts arranged on a circle concentric to shaft. Power is transmitted from driving shaft to flange on driving shaft
through key, from flange on driving shaft to the flange on driven shaft through bolts and then to the driven
shaft through key again. Projection is provided on one of the flanges and a corresponding recess is provided
in the other for proper alignment. Flange coupling is of two types – unprotected and protected.
4.4 Design Procedure
Step 1. Design of Shaft. (d)
Generally power transmitted by shaft is given, hence first of all find torque transmitted by shaft as
𝑷 =
𝟐𝝅𝑵𝑻
𝟔𝟎
For the given Power output (P) and revolution in rpm (N) identify the required Torque (T) in N-
mm, now as per torsion equation,
𝜏 =
𝑇. 𝑅
𝐽
=
𝑇.
𝐷
2
𝜋 𝐷4
32
=
16. 𝑇
𝜋. 𝐷3
≫ 𝑇 =
16
𝜋
× 𝜏 × 𝑑3
∴ 𝒅 = √
𝑻
𝝉
×
𝝅
𝟏𝟔
𝟑
Step 2. Design of Flange, Hub
 Outer diameter of hub, (2 d)
 Pitch circle diameter of bolts, (3 d)
 Outer diameter of flange, (4 d)
 Length of the hub, (1.5 d)
 Thickness of flange, (tf = 0.5 d)
 Thickness of protective circumferential flange, (tp = 0.25 d)
Where (d) is the diameter of shafts to be coupled.

Step 3. Design of Hexagonal Bolt

4.5 Design of Knuckle Joint
There are three main components
1. Eye,
2. Fork and
3. Pin
The eye is formed on one of the rods and the fork is formed on the other. The eye fits inside the fork and the
pin is passed through both the fork and the eye. This pin is secured in its place by means of a split pin. The
ends of the rods are made octagonal to some distance for better grip and are made a square for some portion
before it is forged to make the eye and fork shapes.
Load on the joint
𝑷 =
𝝅
𝟒
× 𝝈𝒕 × 𝒅𝟐
Load on the pin
𝑷 = 𝟐 ×
𝝅
𝟒
× 𝝉 × 𝒅𝟏
𝟐
Load on eye end
𝑷 = (𝒅𝟐 − 𝒅𝟏) × 𝒕 × 𝝈𝒕
𝑷 = (𝒅𝟐 − 𝒅𝟏) × 𝒕 × 𝝉
When d= Diameter of rod
1. Diameter of knuckle pin d1=d
2. Outer diameter of eye d2=2d
3. Diameter of knuckle pinhead or collar d3=1.5d
4. Thickness of single eye rod t=1.25d
5. Thickness of double eye rod t1=1.25d
6. Thickness of knuckle pinhead or collar t2=1.25d

5. 3D Printing
5.1 Introduction:
3D printing is the process of creating a three-dimensional object, usually done by systematically layering
material on top of itself. The printer reads a digital file from the computer which dictates how to layer the
material to build the object.
This is why 3D printing is also known as additive manufacturing. 3D printing and additive manufacturing are
mostly synonymous, although you may hear additive manufacturing used more frequently in the context of
mass consumption or mass manufacturing.
 3D printing or additive manufacturing is a process of making three dimensional solid objects from a
digital file.
 The creation of a 3D printed object is achieved using additive processes. In an additive process an
object is created by laying down successive layers of material until the object is created. Each of these
layers can be seen as a thinly sliced cross-section of the object.
 3D printing is the opposite of subtractive manufacturing which is cutting out / hollowing out a piece
of metal or plastic with for instance a milling machine.
 3D printing enables you to produce complex shapes using less material than traditional manufacturing
methods.
5.2, 3D Printing Process:
Depending on the specific print you are planning to do there could be more or fewer steps in your process.
But in general, 3D printing involves the following actions:
Step 1: Create or Find a Design
The first step of 3D printing typically starts on a computer. You must create your design using a 3D design
software, typically a CAD (computer-aided design) software. If you are unable to create the design yourself,
you can also find many free resources online with free designs.
Step 2: Export the STL File
Once you have created or chosen a design, you must either export or download the STL file. The STL file is
what stores the information about your conceptual 3D object.
Step 3: Choose Your Materials
Typically you may have an idea about what kind of material you will use before you print. There are many
different 3D printing materials available, and you can choose them based on the properties that you want your
object to have. We will discuss this more in-depth below.
Step 4: Choose Your Parameters
The next step is then deciding on the different parameters of your object and the printing process. This
includes deciding on the size and placement of your print.
Step 5: Create the G-code
You will then import the STL file into slicing software, like BCN3D Cura. The slicing software will convert
the information from the STL file into a G-code, which is a specific code containing exact instructions for the
printer.
Step 6: Print
This is when the magic happens! The printer will create the object layer by layer. Depending on the size of
your object, your printer, and the materials used, the job can be done in a matter of minutes or over several
hours.
Step 7: Finishing
Depending on what you want your final product to be or the material you used, there may be additional post-
processing steps after printing, like painting, brushing off powder, etc.

5.3 3D Printing Classifications

5.4 Advantages of additive over conventional (Subtractive) Manufacturing
Additive Manufacturing Subtractive Manufacturing
In additive manufacturing, layer by layer material is
added one over another to develop desired solid 3-D
product.
In subtractive manufacturing, layer by layer
material is gradually removed from a solid block
to fabricate 3-D product.
This manufacturing concept is usually suitable for
materials having low melting point, such as plastic.
This manufacturing concept can be applied to all
solid materials irrespective of melting point.
Volumetric density (thus weight) of the constructive
material of final component can be controlled during
operation.
Material density cannot be controlled during
operation. Density of object remains same with
that of the initial solid block (usually a cast
product).
No material wastage takes place in these processes.
These processes are associated with material
wastage in the form of chips, scraps, dissolved
ions, vapors, etc.
Complex shapes can be easily fabricated using additive
manufacturing techniques.
Subtractive manufacturing processes have
limited capability in fabrication of complex
shapes.
Structures containing fully closed internal hollow parts
can be produced by these processes.
Structures containing enclosed hollow parts
cannot be produced by these processes, unless
joining is allowed.
These processes are applicable to a narrow range of
materials.
These processes can efficiently handle a wide
variety of materials.
These processes are time consuming and costly but can
provide superior quality and desired property without
requiring any further processing.
These processes are time efficient and
economic. These are usually suitable for mass
production where requirement of product
quality is not so tight.
5.5 Applications of 3D Printing

5.6 Modeling for Additive Manufacturing: [Based on part quality, cost and production rate]
5.7 Seven Types of Additive Manufacturing Techniques
a) VAT PHOTOPOLYMERISATION
VAT Photopolymerisation is also known as stereolithography. This type of additive manufacturing uses a
vat of liquid photopolymer resin—which is how VAT Photopolymerisation received its name.
A build platform is lowered from the resin’s top, moving downward, and a laser beam draws a shape in the
resin, creating a layer. The average thickness of one layer is between 0.025 and 0.5mm. After each layer
of resin, it must then be cured using ultraviolet (UV) light.
This process of Photopolymerisation uses motor controlled mirrors to direct the UV across the resin
surface, causing it to harden. These steps are repeated to add layers. For increased accuracy and finish,
most equipment uses blades that go over each layer to remove defects before applying and curing the next
layer. Using a liquid creates a great deal of accuracy and detail in the finished project; however, it lacks
the structural support provided by other types of additive manufacturing. This is corrected by adding
support structures. Although the VAT Photopolymerisation process is quick to complete, the clean-up and
post-processing time is lengthy. VAT Photopolymerisation is used in several industries to create parts and
products ranging from hearing aids to Nike shoes.

B ) MATERIAL JETTING
With material jetting, the print head is above the platform, and material is deposited onto the surface in the
form of droplets. Hundreds of micro-droplets are positioned with charged deflection plates, providing
increased control and accuracy. These droplets then solidify, creating a layer. This is repeated, building up
layers.
The droplets may be distributed continuously or individually using the Drop-on-Demand (DOD) method.
This method is similar to an inkjet printer. Material jetting can be done with various materials, including
polymers and waxes. This type of additive manufacturing is precise, and you can use multiple materials
for one project. Although accurate, it is not the most efficient method as time is spent re-filling the reservoir
that depletes quickly. Material jetting is often used to create realistic models or prototypes.
c) BINDER JETTING
This type of additive manufacturing uses a binder and a powder-based material. This powder-based
material is applied to the build platform with a roller, and then the print head deposits the binder on top.
The binder adheres the layers together and is usually in liquid form. Following a layer, the product is
lowered on the platform. This is repeated to create more layers until the product is finished. When using
this process, you can use different materials, including polymers, ceramics, and metals.
Binder jetting is considered one of the speediest additive manufacturing methods and allows for
customization. For example, if you require material of a specific quality, you can change the binder-powder
ratio, or if you want to create a product that has color variation, you can do so. One of the drawbacks of
binder jetting is the increase in post-processing time, and it may not be the best choice for creating
structural parts. Binder jetting is used in industrial applications, dental and medical devices, aerospace
components, part casting, luxury applications, and more.
d) MATERIAL EXTRUSION
Material extrusion is a type of additive manufacturing process often used in inexpensive at-home 3D
printers where the material is drawn through a nozzle, heated, and then deposited in a continuous stream.
This nozzle moves along horizontally and the platform moves up, down, and vertically. This is how the
layers are created. Because the material is heated (melted) when it is applied, it fuses to the previous layer.
The bonding between layers can also be controlled through temperature and chemical agents.
Although material extrusion is often seen in inexpensive models, it has many capabilities. Polymers and
plastics can be used, which provide strong structural support. However, there are also limitations to this
additive manufacturing process.
 Accuracy is reduced because of the nozzle thickness.
 Material extrusion is also one of the slower types of additive manufacturing.
Many automotive companies use material jetting to create manufacturing devices used in assembly lines.
e) POWDER BED FUSION
For powder bed fusion additive manufacturing, a layer of powder is applied to the platform. A thermal
energy source like an electron beam or laser fuses the powder before a second layer is applied with a roller
or blade. This layering process is then repeated.
There are slight variations within powder bed fusion, including:
 Selective Laser Melting (SLM)
 Selective Laser Sintering (SLS)
 Electron Beam Melting (EBM)
 Direct Metal Laser Sintering (DMLS)

Despite the differences between these variants, all powder bed fusion manufacturing occurs in a near-
vacuum, pre-heated chamber with inert gas. Metals and polymer powder materials can be used, which act
as a support structure, making it a suitable type for prototypes and visual models.
f) SHEET LAMINATION
Sheet lamination is a process that binds layers using ultrasonic welding or an adhesive.
There are two variations of sheet lamination; ultrasonic additive manufacturing (UAM) and laminated
object manufacturing (LOM). The difference between the two is found in the material used and the bonding
process.
 UAM uses metal that is bound together with ultrasonic welding.
 LOM uses paper that is bound together using an adhesive.
Sheet lamination is done by placing the material on a cutting bed. Layers are applied and bonded to that
material and the shape is cut with a knife or laser. This process can bind different materials and is relatively
low cost and speedy. Accuracy is sometimes lacking in sheet lamination and may projects that utilize this
additive manufacturing process may require post-processing. Sheet lamination is often used for
prototypes.
g) DIRECTED ENERGY DEPOSITION
Directed Energy Deposition (DED) is one of the most complex types of additive manufacturing. A four-
or five-axis arm will move around, depositing melted material around a fixed object. The material is melted
by an electron beam or laser and will then solidify.
Metal powder or wires are the most common material used with DED, but ceramics and polymers may also
be used. You can achieve a high degree of accuracy due to the ability to repair and control grain structure
in DED. The finish varies based on the material used. In the case of metal, a powder will provide a much
better finish than wire; however, you can achieve your desired effect with wire through post-processing.
Direct Energy Disposition is often used to repair or fabricate parts.
3D Printing Materials and its forms
One of the most important parts of 3D printing is to use the right kind of material for the job in hand. In this
guide we look at the range of 3D materials, also called filaments, a 3D printer uses, starting with the most
popular. We’ll also cover their uses along with pros and cons for each type. This will help you to make better
informed decisions when buying your 3D printer filaments.
Before you print anything in 3D, there are a few basic questions you should ask yourself, the main ones
include:
 Strength: How strong does your printed part have to be?
 Flexibility: How flexible does your part need to be?
 Accuracy: How important is precision to your 3D part?
 Special conditions: Any other conditions that apply to your 3D model
These are the 3D printing materials that are covered in this guide:
1) ABS Filament
2) PLA Filament
3) PET Filament
4) PETT Filament
5) Nylon Filament
6) PVA Filament
7) Sandstone Filament
8) Wood Filament
9) Metal Filament
10) HIPS Filament
11) Magnetic Iron Filament
12) Conductive Filament
13) Carbon Fiber Filament
14) TPE Filament
15) Glow in the Dark Filament
16) Amphora Filament

3D Printing Post Processing Requirement and Techniques.
Parts manufactured with 3D printing technologies usually require some degree of post-production
treatment. This important step of the 3D printing process is known as post-processing. In short, post-
processing in 3D printing refers to any process or task that needs to be performed on a printed part, or any
technique used to further enhance the object. Think of it as a finishing touch to treat and refine parts that
come out of a 3D printer. The options for post-processing 3D printed parts include removing support or
excess material, washing and curing, sanding or polishing a model to painting or coloring.
We can identify 5 steps in post-processing, although not all steps are required for all projects:
1. Cleaning
2. Fixing
3. Curing or hardening
4. Surface finishing
5. Coloring
Many different post-processing techniques are employed and we will try to understand 8 such techniques
for post-processing of FDM 3D printed parts.
a) Support removal
Support removal is the first technique employed for post-processing of FDM 3D printed parts. Mainly,
there are two types of support materials, Insoluble and Soluble.
 Insoluble: Insoluble materials are the generic materials like PLA, ABS, Nylon, PC, etc. These are
either removed by hand or by pliers and flush cutters. However, sometimes the supports are located
in critical positions and it becomes difficult to reach and remove them.
 Soluble: Soluble materials like HIPS (used as a support with ABS material) and PVA (used as a
support with PLA material) are far easier to operate with as they dissolve in a chemical called
Limonene and water respectively.
Support removal usually leaves some marks on the touch points but these can be post-processed further for
a smoother finish.
b) Sanding
It is one of the simplest method for post-processing of FDM 3D printed parts. It is similar to sanding wood
objects but it requires a lot of effort. The sanding has to be carried out in successive stages starting from a
low grit sandpaper (usually 150 grit) and moving towards higher grit sandpapers like 400grit, 600 grit till
2000 grit or even more depending on the requirement. The drawback of sanding is the amount of time and
effort it takes. Additionally, the material is unequally removed so the dimensional accuracy of the part will
be hampered. Apart from this, the fine particles of the material are released into the air and can enter the
lungs while breathing so it is recommended to use a mask while sanding 3D printed parts.
c) Vapour smoothing
Acetone is used in this post-processing technique. This technique is usually employed while operating with
ABS filament. The 3D printed object is exposed to vapours of acetone in a closed environment. The vapours
react with the outer layer of the object and it starts to melt. The process melts the layer lines and
smoothening the outer layer of the object giving it a glossy look.
Again the drawback of employing this technique is the unequal removal of the material which affects the
dimensional accuracy of the product. Since the process cannot be controlled the part has to be constantly
observed and has to be removed from the enclosure once the desired finishing is achieved. This method
can be used for luxury goods where aesthetics are more important than dimensional accuracy.

d) Priming & Painting
Priming is the process of coating the part with primer. It mostly acts as a base for a further painting job.
Priming and painting are one of the most popularly employed post-processing techniques for FDM 3D
printed parts. Priming can be carried out only after the 3D printed part is sanded with a moderate grit
sandpaper (close to 600 grit). After sanding the part, spray the primer onto the part in two separate coats.
Do take care of the safety precautions before spraying the primer and even while painting in the next step.
After the first coat of primer, sand the part again and then follow it up with a second coat of primer. Spray
the primer in quick light sprays.
After priming, let the model dry and then painting can be carried out. Painting can be regular painting with
a brush or by using sprays. While painting with brush can help in making intricate designs, the spray
painting will be a quick approach to paint specific colour regions. One tip is to mask the parts not to be
painted by a specific colour, as this will help in sharp colour intersections.
e) Polishing
Polishing can be achieved by using buffing wheel using a Dremel tool. A separate 3D printing Dremel
toolkit is available for makers and creators to buy. Polishing is done only after sanding. This will enhance
the finish of the print.
f) Electroplating
Electroplating is a great option for post-processing of FDM 3D printed parts. Generally, plating services
are available. ABS can be easily and readily electroplated and such a care should be taken while choosing
the material for the part. Electroplating can not only enhance the look and feel but also increases the
strength of the part.
g) Gluing and Welding
In case of parts bigger than the build volume of the printer, the part is broken down into multiple pieces.
At such times, the PLA parts can be easily glued together by bonding agents like Anabond, mostly used in
industrial applications. ABS prints can be welded together. Welding here is by means of acetone. Light
layers of acetone can be applied to the mating surfaces and held together under force or by clamping. This
will cause the bond to be chemically glued together. Such bonds are pretty strong. More the surface area
of the mating parts, more strong will be the bond.
h) Hydrographics
One of the most exciting techniques for post-processing of FDM 3D printed parts is Hydrographics. It is
also called Hydro Dipping, Immersion printing Water Transfer printing, water transfer imaging, etc., is a
process of applying printed graphic designs to solid objects. This post-processing technique is used on
various materials like plastics, metals, wood, glass, etc.
5.8 Additive Manufacturing Product Quality, Inspection and Testing
Additive manufacturing product is tested for many variety which includes:
 Powder characterization
 Chemical analysis
 Failure analysis
 Fatigue testing
 Tensile testing
 Impact testing
 Hardness testing
 Creep and stress rupture testing
 Fracture toughness testing
 Compression testing

5.9 Additive Manufacturing Defects and their causes
5.10 Causes process parameters

Product Design and Development 20ME43P C-20 Lab Manual.pdf

Product Design and Development 20ME43P C-20 Lab Manual.pdf

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Product Design and Development 20ME43P C-20 Lab Manual.pdf

Ähnlich wie Product Design and Development 20ME43P C-20 Lab Manual.pdf (20)

Mehr von THANMAY JS

Mehr von THANMAY JS (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Product Design and Development 20ME43P C-20 Lab Manual.pdf