machine design 1

1. INTRODUCTION OF MACHINE
DESIGN-I
Prof. Jawed B. Shaikh
Department of Mechanical Engineering
Deogiri Institute of Engineering and Management studies Aurangabad.

3. MACHIN
E
DESIGN
TOM
METALLUR
GY
SOM
PRODUCTI
ON
TECHNIQU
ES
APPLIED
MECHANICS
MACHINE
DRAWING

4. BASIC REQUIREMENTS OF MACHINE ELEMENTS
“A machine consists of machine elements. Each part of a machine, which has motion with respect to some
other part, is called a machine element.
(i) Strength
(ii) Rigidity
(iii) Wear Resistance
(iv) Minimum Dimensions and Weight
(v) Manufacturability
(vi) Safety
(vii) Conformance to Standards
(viii) Reliability
(ix) Maintainability
(x) Minimum: Life-cycle Cost

5. COURSE CONTENTS:
Unit1: Mechanical Engineering Design Process [07 Hours]
Traditional design methods, general industrial design procedure, design considerations,
phases in design, creativity in design, use of standardization, preferred series,
introduction to ISO9000, use of design data book, aesthetic and ergonomic
considerations in design.
Unit2: Design of Machine Elements against Static Loading [07 Hours]
Theories of Failure (Yield and Fracture Criteria): Maximum normal stress theory, Maximum shears
tress theory, Maximum distortion energy theory, comparison of various theories of failure, Direct
loading and combined loading, Joints subjected to static loading e.g. cotter (Bicycle pedal, piston rod in
crosshead in steam engine and piston rod with extension) and knuckle joint.

6. Unit3: Design of Machine Elements against fluctuating loading [07 Hours]
Stress concentration, stress concentration factor, fluctuating stresses, fatigue failure ,
endurance limit, notch sensitivity, approximate estimation of endurance limit, design for
finite life and ifinite life under reversed stresses, cumulative damage in fatigue, Soderberg
and Goodman diagrams, fatigue design under combined stresses.
Unit4: Design of shaft keys and coupling
Various design considerations in transmission shafts, splined shafts, spindle and axles
strength,
lateral and torsional rigidity, ASME code for designing transmission shaft.Types of Keys:
Classification and fitment in keyways, Design of various types of keys.
Couplings: Design consideration, design of rigid, muff and flange type couplings, and
design of
flexible couplings

7. .
Unit5: Design of Threaded Joints and Mechanical Springs [07 Hours]
Power Screws: Forms of threads used for power screw and the its applications, torque
analysis
for square threads, efficiency of screw, overall efficiency, self-locking in power screws,
stresses
in the power screw, design of screw and nut, differential and compound screw, re-
circulating ball
screw.
Welded Joints: Type of welded joints, stresses in butt and fillet welds, strength of welded
joints
subjected to bending moments.
Mechanical Springs: Stress deflection equation for helical spring, Wahl’s factor, style of
ends,
design of helical compression, shot peening

8. 1. V. B. Bhandari, “Design of Machine Elements”, Tata McGra Hill
Publications,New Delhi,2008.
2. R. L. Nortan, “Machine Design: An Integrated Approach”Pearson
Education Singapore,2001.
3. Machine Design –R. S. Khurmi
4.J. E. Shigley and C. Mischke, “Mechanical Engineering Design”, Tata
McGraw Hill
Publications,7thedition, 2004.
5. M. F.Spotts, “Design of Machine Elements”, Prentice Hall of India,
New Delhi.
**1.Design data book-R.B.Patil

9. WHAT IS DESIGN ?
• Design is to formulate a plan for a specified need or solve a specific problem
.It is a plan that results in creation of something having physical reality. It is
an innovative and a highly iterative process.
Idea Physical product
FUNCTION
AL
SAF
E
USABLE
RELIABL
E
MANUFACTURA
BLE
COMPETITIVE MARKETABL
E

10. • “Machine is defined as a the use of scientific principles
,technical information and imagination in the description
of a machine or mechanical system to perform specific
functions with maximum economy and efficiency”
• An apparatus using mechanical power and having several parts, each with a definite function
and together performing a particular task.
• Semi or fully automated device that magnifies human physical and/or mental
capabilities in performing one or more operations.
WHAT IS MACHINE?

11. • Machine is a combination of several machine elements
arranged to work together as a whole to accomplish specific
purpose.
• Machine Design involves designing the elements and
arranging them optimally to obtain some useful work.
• Machine design is the process of engineering design. A
machine is made up of mechanisms that work together to
satisfy the requirements of what the machine needs to
accomplish.
What is Machine Design?

12. Traditional Design Methods
1. Design by Craft Evolution
2. Design by Drawing
1. Design by Craft Evolution
a. There are no dimensions to the drawing
b. There is no any adequate justification to the drawings
c. The products are developed by trial and error method
d. Any modification in the product is costly, because the craftsman
has to experiment with the product itself. Moreover, only one
change at a time can be attempted and complete reorganization
of the product is difficult.
e. There is no symbolic medium to record the design information of
the product
f. No sudden changes in design
g. No mass production is possible

13. Traditional Design Methods
2. Design by Drawing
a. The dimensions of the product are specified in advance of its manufacture.
b. The complete manufacturing of the product can be subdivided into separate
pieces, which can be made by different people.
c. When the product is to be developed by trial and error, the process is carried
out on a drawing board instead of shop floor. The drawings of the product
are modified and developed prior to manufacture.
d. In this method, much of the intellectual activity is taken away from the shop
floor and assigned to design engineers.

14. Types of Machine Design
Types of design
Adaptive
Design Development
design
New
Design

15. 1) Adaptive Design:- The designer’s work is concerned with
adaptation of existing design. The designer only makes minor
alternation or modification in the existing designs of the product.
2) Development Design:- This type of design needs considerable
scientific training and design ability in order to modify the existing
design into a new idea by adopting a new material or different
method of manufacture. The designer starts from the existing
design, but final product may differ quite markedly from the
original product.
3) New Design:- This type of design needs lots
of research, technical
ability and creative thinking.
Types of Machine Design

16. Types of Design Based on method
Types of design
based on
method
Rational
Design Empirical
Design
Industrial
Design

17. 1) Rational Design:- Based on determining the stresses and
strains of components and thereby deciding their
dimensions. This type of design depends upon
mathematical formulae of principal of mechanics.
1) Empirical Design:- This type of design depends upon
empirical formulae based on the practice and past
experience .
1) Industrial Design:- This type of design depends upon the
production aspects to manufacture any machine
component in the industry. Based on industrial
Types of Design Based on method

18. ⮚What device or mechanism to be used-
⮚To decide the relative arrangement of the constituent elements.
⮚Material
⮚Forces on the elements
⮚Size
⮚Shape and space requirements
⮚Weight of the product
Factors to be considered in Machine
Design

19. ⮚The method of manufacturing the components and their
assembly.
⮚How will it operate.
⮚Reliability and safety aspects.
⮚Inspectibilty
⮚Maintenance
⮚Cost and aesthetics of the designed product.
Design

20. General Industrial Design Procedure
Flow Chart for the General Procedure

21. ⮚Standardization is defined as obligatory (or compulsory) norms, to
which various characteristics of a product should comply (or
agree) with standard.
⮚The characteristics include materials, dimensions and shape of the
component, method of testing and method of marking, packing
and storing of the product.
⮚A standard is defined as a set of specifications for parts, materials
or processes. The objective of, a standard is to reduce the variety
and limit the number of items to a reasonable level.
Standardization

22. • On the other hand, a code is defined as a set of specifications
for the analysis, design, manufacture, testing and erection of the
product. The purpose of a code is to achieve a specified level
of safety.
• There are three types of standards used in design :-
⮚ Company Standards: They are used in a particular
company or a group of sister concerns.
Standardization

23. ⮚National standards:
– India - BIS (Bureau of Indian Standards),
– Germany - DIN (Deutsches Institut für Normung),
– USA - AISI (American Iron and Steel Institute) or SAE (Society of Automotive
Engineers),
– UK - BS (British Standards)
⮚International standards: These are prepared by the International
Standards Organization (ISO).
Standardization

24. ⮚ Standards for Materials, their chemical compositions, Mechanical
properties and Heat Treatment:
For example, Indian standard IS 210 specifies seven
grades of grey cast iron
designated as FG 150, FG 200, FG 220, FG 260, FG 300, FG 350 and FG 400. The
number indicates ultimate tensile strength in N/mm2.
⮚ Standards for Shapes and dimensions of commonly used Machine Elements:
The machine elements include bolts, screws and nuts, rivets, belts and chains, ball
and roller bearings, wire ropes, keys and splines, etc
For example, IS 2494 (Part 1) specifies dimensions and shape of the cross- section of
endless V-belts for power transmission.
The dimensions of the trapezoidal cross-section of the belt, viz. width, height and
included angle are specified in this standard
Standards are used in mechanical
engineering design

25. ⮚ Standards for Fits, Tolerances and Surface Finish of Component:
For example, selection of the type of fit for different applications is illustrated in IS
2709 on 'Guide for selection of fits'.
The tolerances or upper and lower limits for various sizes of holes and shafts are
specified in IS 919 on 'Recommendations for limits and fits for engineering'.
IS 10719 explains method for indicating surface texture on technical drawings.
⮚ Standards for Tes ting of Products:
These standards, sometimes called 'codes', give procedures to test the products
such as pressure vessel, boiler, crane and wire rope, where safety of the
operator is an important consideration.
For example, IS 807 is a code of practice for design, manufacture, erection and
testing of cranes and hoists.
Standards are used In mechanical
engineering design

26. ⮚ Reductions in types and dimensions of identical components (inventory
control).
⮚ Reduction in manufacturing facilities.
⮚ Easy to replace (Interchangeability).
No need to design or test the elements.
⮚ Improves quality and reliability.
⮚ Improves reputation of the company which manufactures standard
components.
⮚ Sometimes it ensures the safety.
⮚ It results in overall cost reduction.
Benefits of Standardization

27. ⮚ With the acceptance of standardization, there is a need to keep the
standard sizes or dimensions of any component or product in discrete steps.
⮚ The sizes should be spread over the wide range, at the same time these
should be spaced properly.
⮚ For example, if shaft diameters are to be standardized between 10 mm and
25 mm, then sizes should be like : 10 mm, 12.5 mm, 16 mm, 20 mm, 25 mm and
not like : 10 mm, 11 mm, 13 mm, 18 mm, 25 mm.
⮚ This led to the use of geometric series known as series of preferred
numbers
or preferred series.
⮚ Preferred series are series of numbers obtained by
geometric progression and rounded off.
Preferred
Numbers

28. • There are five basic series with step ratios of:
80
5 10 , 10 10 , 20 10 , 40 10 &
10
• These ratios are approximately equal to 1.58, 1.26, 1.12, 1.06 and 1.03.
• The five basic series of preferred numbers (knownas
preferred series) are designated as: R5, R10, R20, R40, and R80.
• The examples of preferred number series are:
standard shaft diameters, power rating of coupling, center
distances of standard gear boxes, etc.
Preferred
Numbers

29. • The difference in two successive terms has a fixed percentage.
• It provides small steps for small quantities and
large steps
for large quantities.
• The product rangeis covered with minimum
number of sizes without restricting the
choice of the customers.
Advantages Preferred
Numbers

30. • The difference in two successive terms has a fixed percentage.
• It provides small steps for small quantities and
large steps
for large quantities.
• The product rangeis covered with minimum
number of sizes without restricting the
choice of the customers.
Advantages Preferred
Numbers

31. R5 R10 R20 R40
1.00 1.00 1.00 1.00
1.06
1.12 1.12
1.18
1.25 1.25 1.25
1.32
1.40 1.40
1.50
1.60 1.60 1.60 1.60
1.70
1.80 1.80
1.90
2.00 2.00 2.00
2.12
2.24 2.24
2.36
2.50 2.50 2.50 2.50
2.65
2.80 2.80
3.00
3.15 3.15 3.15
3.35
3.55 3.55
3.75
4.00 4.00 4.00 4.00
4.25
4.50 4.50
4.75
5.00 5.00 5.00
5.30
5.60 5.60
6.00
6.30 6.30 6.30 6.30
6.70
7.10 7.10
7.50
8.00 8.00 8.00
8.50
9.00 9.00
9.50

32. • In a present days of buyer's market, with anumber of products available in
the market are having most of the parameters identical, the appearance of
product is often a major factor in attracting the customer.
• This is particularly true for consumer durables like: automobiles, domestic refrigerators,
television sets, etc.
• Aesthetics is defined as a set of principles of appreciation of beauty. It deals
with the appearance of the product.
• Appearance is an outward expression of quality of the product and is the first
communication of the product with the user.
• For any product, there exists a relationship between the functional requirement and
the appearance of a product.
Aesthetic
Considerations

33. • The aesthetic quality contributes to the performance of the product, though
the extent of contribution varies from the product to product.
• The following guidelines may be used in aesthetic design (design for
appearance):
• The appearance should contribute to the performance of the product.
For example, the aerodynamic shape of the car
will have a lesser air resistance, resulting in the lesser
fuel consumption.
• The appearance should reflect the function of the product.
For example, the aerodynamic shape of the car indicates the speed.
• The appearance should reflect the quality of the product.
Aesthetic
Considerations

34. • The appearance should not be at too much of extra cost unless it is a prime
requirement.
• The appearance should be suitable to the environment in which the product is
used.
• The growing importance of the aesthetic considerations in product design has
given rise to a separate disciple known as industrial design.
• The job of an industrial designer is to create new shapes and forms for the
product which are aesthetically appealing
– Form (Shape)
There are five basic forms of the products, namely, step, taper, shear, streamline and sculpture
Aesthetic
Considerations

35. ⮚ Step form:
The step form is a stepped structure having vertical accent
It is similar to the shape of a multistorey building.
⮚ Taper form
The taper form consists of tapered blocks or tapered cylinders.
⮚ Shear form
The shear form has a square outlook.
⮚ Streamline form
The streamline form has a streamlined shape having a smooth flow as seen in automobile and
aeroplane structures
⮚ Sculpture form
Aesthetic Considerations

36. Aesthetic
Considerations
The sculpture and stream forms are suitable for mobile products like vehicles, while step
and shear forms are suitable for stationary products

37. • Colour
❑ Colour is one of the major contributors to the aesthetic appeal of the product.
❑ Many colours are linked with different moods and conditions.
❑ The selection of the colour should be compatible with the conventions.
❑ Morgan has suggested the colour code given in the following Table.
Aesthetic
Considerations
Colour Meaning
Red Danger, Hazard, Hot
Orange Possible Danger
Yellow Caution
Green Safety
Blue Caution-Cold
Grey Dull

38. • Material and Surface Finish
❑ The material and surface finish of the productcontribute
significantly to the appearance.
❑ The material like, stainless steel gives better appearance than the cast irons,
plain carbon steels or low alloy steels.
❑ The brass or bronze give richness to the appearance of the product.
❑ The products with better surface finish are always aesthetically pleasing.
❑ The surface coating processes like: spray painting, anodizing,
electroplating,
etc. greatly enhances the aesthetic appeal of the product.
Aesthetic Considerations

39. • Ergonomics is defined as the scientific study of the man-machine-working
environment relationship and the application of anatomical, physiological
and psychological principles to solve the problems arising from this
relationship
• The word ergonomic is formed from two Greek word: ergo means work and
nomic mean natural laws.
• The final objective of the ergonomics is to make the machine fit for user rather
than to make the user adapt himself or herself to the machine.
• It aims at decreasing the physical and mental stresses to the user.
• Psychology - Experimental psychologists who study people at work to provide
data on such things as: Human sensory capacities, psychomotor
performance, Human decision making, Human error rates, Selection tests and
procedures, Learning and training.
Ergonomic
Considerations

40. • Anthropometry - An applied branch of anthropology concerned with the
measurement of the physical features of people. Measures how tall we are,
how far we can reach, how wide our hips are, how our joints flex, and how
our bodies move.
• Applied Physiology - Concerns the vital processes such as cardiac function,
respiration, oxygen consumption, and electromyography activity, and the
responses of these vital processes to work, stress, and environmental
influences.
Ergonomic Considerations

41. Ergonomic Considerations
Man-Machine Closed Loop System

42. Ergonomic Considerations
• This man-machine closed loop system in influenced by the working environmental
factors such as: lighting, noise, temperature, humidity, air circulation, etc.
• Ergonomic Considerations in Design of Displays
• Ergonomic Considerations in Design of Controls
• Working Environment.
• Lighting
• Noise
• Temperature
• Humidity and air circulation

43. THANK YOU