April 8, 2023 Machine Design 1
www.geocities.com/ssroy99/homepage.html
Shibendu S. Roy
Dept. of Mechanical Engineering
April 8, 2023 Machine Design 2
Reference Books1. V.B. Bhandari, “Design of Machine Elements ”, <second edition>, Tata McGraw Hill.
2. J.E. Shigley, C.R. Mischke, “Mechanical Engineering Design”, Tata McGraw Hill.
Machine Design HandbookMachine Design Handbook
1. “Design Data”, Compiled by Faculty of Mechanical Engineering, PSG College, Coimbatore
2. “CMTI Hand Book”, Compiled by Scientists of Central Manufacturing technology Institute, Bangalore
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Chapter Topics
Introduction - Review of Stress, Strain and Complex stresses in machine members- Basic procedure of machine design & machine element design- Manufacturing & other consideration in machine design- Modern Computational Tools for Machine Design- Role of CAD/CAE in Machine Design
Engineering Materials - Mechanical properties of Engineering materials- B.I.S system of designation of commonly used Engineering Materials- Selection of Materials
Rod Joints - Cotter Joint- Knuckle Joint
Plate Joints - Threaded Joints
- Welded Joints
Topics to be Covered
Design against Static Load - Elastic failure theories, Factor of safety, Service factor- General principles & procedures of design of machine elements
Design against Dynamic Load - Stress Concentration factor, Fatigue failure, Endurance limit etc. - Reversed stresses- design for finite & infinite life, Impact stresses etc.
Design of Shafts, Keys, Splines - Design of Shaft under Torsion, Bending, Axial & Combined loads - Design of keys like square & flat, saddle, sunk, woodruff keys etc.
Statistical Considerations in Design - Reliability, Probabilistic approach to Design etc..
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Design of Machine Element
Cam
C-frame
Spring
Brake
Connecting rod
GearDrive
Shaft & Axle
Welded Joint
Belt, Rope, chain Drive
Bearing
Key
IC engine parts
Pressure vessel
Cotter & KnuckleJoint Bolted Joint
RivetedJoint
Clutch
Coupling
Power Screw
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Machine Design
Mechanism
Kinematic Link
MachineMachineMachine Tool
Kinematic Pair
One link fixed
All Machines are Mechanism but all Mechanisms are not Machine
All Machine Tools are Machine but all Machines are not Machine Tool
Mechanism
transfers
transforms
Motion
transfers
transforms
Energy
Kinematic Chain
MachineMachine
Machine tool is a contrivance having a combination of mechanisms/machines whereby a cutting tool is enabled to operate in a pre-conceived manner in order to produce a surface of desired shape, size or a degree of finish by removing metal from workpiece in the form of chips.
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Design
Design SynthesisDesign Analysis
Mechanismis given
Inputs Outputs
Machine Design
Given Configuration, material & assume mode of
failure
determines the dimension
decision –making process
process of creating new configuration/ mechanism
Selecting optimum/best configuration from no. of existing mechanism
Selecting materials from no. of alternative materials
Determination of optimum shape & dimensions of the component on the basis of design analysis
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Identification of Need
Engineering Analysis
Problem definition, Design specification
Collecting relevant design information & feasibility study
Design Conceptualization/ Preliminary design i.e. Mechanism synthesis
General Procedure in Machine DesignGeneral Procedure in Machine Design
Detail Design of Components
Design Optimization
Modeling & Simulation
Design Evaluation
Customer
Manufacturer
CAD/CAE
Design Synthesis
Design Analysis
Design Communication & Documentation
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Basic Procedure of Design of Machine Element
Basic Procedure of Design of Machine Element
Specify functions of element
Determine forces acting on element
Check design at critical cross-sections
Determine failure mode (s) of element
Select suitable material for element
Check & modify dimensions for assembly & manufacture
Determine geometric dimensions of element based on above failure mode
Prepare detail engineering drawing of element
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Strength
Manufacturability
Conformance to Standards
Minimum Dimensions & Weight
Rigidity
Minimum Life Cycle cost
Reliability
Safety
Wear Resistance
Maintainability
Basic Requirements of Machine ElementsBroad objective of designing a machine element is to ensure that it preserves its operating capacity during the stipulated service life with minimum manufacturing & operating costs
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“Standards” in Machine Design
Standardization Standardization is defined as obligatory norms, to which various characteristics of a product should conform.
The characteristics include materials, dimensions and shape of the component, method of testing and method of marking, packing and storing of the product.
Standard Standard is defined as a set of specifications for parts, materials or processes
Code is defined as a set of specifications for the analysis, design, manufacture, testing and erection of the product
Purpose of Code Purpose of Code to achieve a specified level of safety
Purpose of Standard Purpose of Standard to reduce the variety & limit the no. of items to a reasonable level
Code
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“Standards” in Machine DesignAdvantages of Standardization Advantages of Standardization
The reduction in types & dimensions of identical components, to a rational number, makes it possible to manufacture the standard component on mass scale in a centralized process.
Standard parts are easy to replace when worn out due to interchangeability.
The application of standard machine elements & especially the standard units reduce the time & effort needed to design a new machine.
Standardization results in substantial saving in Designer’s effort The standards of specifications & testing procedures of machine elements improve their
quality & reliability.
In designing, the aim is to use as many standard components as possible for a given machine
International Standards
National Standards
Company Standards
Types of Standards Types of Standards
I.S / B.I.S India B.S UK A.I.S.I / S.A.E USA D.I.N German
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“Standards” in Machine Design
SP 46 Bureau of Indian Standards on “Engineering Drawing Practice for Schools & Colleges
I.S. 210 Seven grades of grey cast iron
I.S. 1570 : Chemical composition of various grades of alloy steel
I.S. 733 : 1983 Mechanical Properties of wrought Al. & Al alloy Bars, Rods for general purposes
I.S. 736 : 1986 Mechanical Properties of wrought Al. & Al alloy Plates for general purposes
I.S. 919 Recommendations for Limits & Fits for Engineering
I.S. 2709 Guide for selection of fits
I.S. 8000 Geometrical tolerancing on technical drawings
I.S. 4218 : 1996 Designation & Dimension of screw threads, bolts & nuts
Indian Standards in Mechanical Engineering Design
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Preferred Numbers When a machine is to be made in several sizes with different powers or capacities, it is
necessary to decide what capacities will cover a certain range efficiently with minimum number of sizes.
For example, a company want to manufacture seven different models of electric motors ranging from 0.25 HP to 5 HP to cater to the need of different customers.
Preferred numbers are used to specify the ‘sizes’ of the product in these cases.
French Engineer Charles Renard first introduced Preferred Numbers in the 19th century.
The system is based on the use of geometric progression to develop a set of numbers.
Basic series
Common Ratio
% increase in steps
Preferred Numbers [in between 1 to 10]
R 5 series 101/5 1.58 58% 1.0, 1.6, 2.5, 4.0, 6.3, 10.0
R 10 series 101/10 1.26 26% 1.0, 1.25, 1.6, 2.0, 2.5, 3.15, 4.0, 5.0, 6.3, 8.0,10.0
R 20 series 101/20 1.12 12% 1.0,1.12,1.25,1.4,1.6,1.8,2.0,2.24,2.5,2.8,3.15,3.55,4.0,4.5,5.0,5.6,6.3,7.1,8.0,9.0,10.0
R 40 series 101/40 1.06 6% 1.0,1.06,1.12,1.18,1.25,1.32,1.4,1.5,1.6, ……………………………………, 10.0
R 80 series 101/80 1.03 3% 1.0,1.03, 1.06,1.09, 1.12,1.16, 1.18, 1.21,1.25,1.29,1.32,1.36,1.4,…..1.6, ………, 10.0
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Aesthetic Considerations in Machine Design
When there are a number of products in the market, having the same qualities of efficiency, durability and cost, the customer will naturally attracted towards the most appealing product.
The external appearance is an important feature, which not only gives grace and luster to the product but also dominates the sale in market.
Automobiles Audio Visual EquipmentsHousehold Appliances
Industrial DesignIndustrial DesignThe job of an Industrial Designer is to create new forms & shapes, which are aesthetically pleasing.
The external appearance of the products is a cumulative effects of number of factors :
ColourForm Surface finish & Tolerances Materials Manufacturing Methods
In many cases, functional requirements result in shapes, which are aesthetically pleasing. The evolution of the streamlined shape of the boeing is the result of studies in aerodynamics for effortless speed.
Chromium plating on the household appliances is for corrosion resistance rather than for pleasing appearance
Relationship between Functional requirement & Appearance of the Product
Stream
Sculpture
Step
Taper Shear
April 8, 2023 Machine Design 15
Ergonomic Considerations in Machine Design
Ergonomics is defined as the relationship between Man & Machine and the application of anatomical, physiological and psychological principles to solve the problems arising from Man-Machine relationship.
Anatomical factors in design of driver’s seat.
Layout of instrument dials & display panels for accurate perception by the operators
Design of hand levers & hand wheels.
Topics of Ergonomic studies in machine designTopics of Ergonomic studies in machine design
Ergonomists have carried out experiments to determine the best dimensions of driver’s seat, the most convenient hand or foot pressure or dimensions of levers and hand wheels.
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Concurrent Engineering: Simultaneous Design Process
Cost,Sales &
servicing
Customer’s requiremen
t
Ergonomics &
Appearance
Reliability, Maintainability
& safety
Manufacturability & Testability
Marketing Department
Design Office
Production Department
Sales & Service Department
Sequential Design ProcessSequential Design Process Concurrent Engineering Concurrent Engineering
Concurrent Engineering is defined as the design process that brings both design & manufacturing engineers together during the early phases of the design process.
Design Engineering
: Concurrent Engineering Concept
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RequirementsRequirements Most Productive
Most Economic
Improved Quality
Motivation
Successful entry of a product into the market can best occur if it can complete the above cycle in the shortest possible time & at the lowest cost while maintaining very high product quality & reliability
CAD Computer Aided Design
CAE Computer Aided Engineering
CAM Computer Aided Manufacturing
VP & VR Virtual Prototyping & Virtual Reality
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is the use of wide range of computer based tools that assist Engineers & other Design Professionals in their design activities.
is to design, develop and optimize the product.
is the use of Information technology/ computer based tools for supporting Engineers in tasks such as Design, Analysis, Simulation, Optimization, Manufacturing, Planning etc.
is to design, develop and optimize the product or process.
CAE areas:
Stress analysis, Vibration analysis using FEM
Thermal & fluid flow analysis using CFD
Kinematic & Dynamic Analysis & Simulation
Analysis tools for manufacturing process simulation
Optimization of the product or process
is the use of wide range of computer based tools that assist Production Engineers & Tool and Die maker, CNC machinists, in the manufacture or prototyping of products.
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RequirementsRequirements Most Productive
Most Economic
Improved Quality
MotivationSuccessful entry of a product into the market can best occur if it can complete the above cycle in the shortest possible time & at the lowest cost while maintaining very high product quality & reliability
VP : Virtual PrototypingVP : Virtual Prototyping
VP is about Presentation, Testing, & Analysis of 3-D CAD models prior to creating any physical prototype
Visualization Models : greater communication, productivity & efficiency through realistic graphical modelling based on full colour, natural texture & appearance, dynamic viewing of models from any user-specified angle & orientation.
Fit & Interference checking of mechanical assemblies
Testing & Verification of functions & performance : Structural & Physical phenomena analysis [FEM, CFD], Motion analysis.
Manufacturing Evaluation
Assembly analysis
Human factor analysis
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CAD-CAM-CAE Software
CAD/CAM/CAE software Purpose
CATIA
3-D modeling, analysis & simulation etc.NX (UniGraphics + IDEAS)
PRO-ENGINEER
SOLID WORKS
SOLID EDGE
INVENTOR
Mechanical DESKTOP
MasterCAM
3-D modeling & manufacturing simulationSolidCAM
SmartCAM
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CAD-CAE SoftwareCAE software Purpose
ADAMS Multi-body dynamic analysis & simulation
SimDESIGNER with CATIA Multi-body dynamic analysis & simulation
Visual NASTRAN Multi-body dynamic analysis & simulation
Working Model Multi-body dynamic analysis & simulation
ANSYS Finite Element Analysis
NASTRAN Finite Element Analysis
ABAQUS Finite Element Analysis
LS-DYNA Finite Element Analysis, Crash simulation
DEFORM Finite Element Analysis, Crash simulation
PAMCRASH Finite Element Analysis, Crash simulation
FLUENT Computational Fluid Dynamics
Altair Hyper Mesh Meshing for Finite Element Analysis
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Computational Tools
Software Purpose
MATLAB Design calculation, dynamic analysis & simulation, design optimization, control
MathematicaDesign calculationMathCAD
Maple
TK Solver
Excel
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Design Phase Required CAD-CAE Tools Related Software (s)
Design conceptualization
Geometric modeling, Graphics aids, visualization
CATIA, NX, SolidWorks, Solid Edge, Pro-E, Inventor…
Modeling & Simulation
Geometric modeling, Graphics aids, visualization, Simulation Package
CATIA…, ADAMS….
Design Analysis Geometric modeling, Analysis Package, visualization
CATIA…, NASTRAN, ANSYS…
Design Optimization
Geometric modeling, Optimization module
CATIA…, MATLAB…
Design Evaluation Geometric modeling, Customized programs & Package
CATIA…
Design communication & documentation
Geometric modeling, Drafting package
CATIA…, AutoCAD…
CAD-CAE Tools
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3-D CAD model3-D CAD model Pre-Processor Solver Post-Processor
CAD-CAE Tools
CAD
CAE
Define the model & environment factors to be
applied
Performed computation on
high end computer
Display results in graphical form using visualization tools
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Assignment # 11. Explain with example, the different steps involved in machine design process & in design of machine
elements? What are the basic requirements of machine elements?
2. Distinguish between design synthesis and design analysis.
3. What is Standardization & what are the advantages of standardization? Give examples of Indian standards for commonly used engineering materials.
4. What are preferred numbers? How many basic series are used? What is R10 series? Develop R 10 series from 2 to 20.
5. What is an industrial design? What is the relationship between functional requirement and external appearance of the product.
6. Define ergonomics. What is the scope of ergonomics in machine design?
7. Distinguish between sequential design and concurrent engineering.
8. Explain the functional area of a basic CAD-CAE system & their applications & benefits in machine design process with examples.
9. Class Test Problem # 1.
10. Class Test Problem # 2.
Last date of submission : 08th February, 2008
April 8, 2023 Machine Design 27
Thank You