Product cycle- Design process- sequential and concurrent engineering- Computer aided design – CAD system

PRODUCT LIFE CYCLE (PLC) AND DESIGN
PROCESSES
Every product goes through a cycle from birth, followed by an initial growth stage, a relatively stable matured
period, and finally into a declining stage that eventually ends in the death of the product as shown schematically
in the figure above.

Understanding the Product
Life Cycle
Introduction Stage
In this stage the product is new and the customer acceptance is low
and hence the sales are low.
Growth Stage
Knowledge of the product and its capabilities reaches to a
growing number of customers.
Maturity Stage
The product is widely acceptable and sales are now stable,
and it grows with the same rate as the economy as a whole
grows.
Decline Stage
At some point of time the product enters the decline stage.
Its sales start decreasing because of a new and a better
product has entered the market to fulfill the same
customer requirements.

Product Life Cycle for Continuous
Improvement
The product life cycle can be used as a framework for continuous improvement. As shown in the image above, the
cycle provides opportunities at each stage to refine and enhance the product to extend its life and maximize its
value in the market.

Design Process Models
Design is an activity that needs to be well organized and should take into account all influences that are likely to
be responsible for the success of the product under development. The following models are considered in design
purpose:
1 Shigley
A systematic approach to engineering design
with emphasis on mechanical systems.
2 Pahl and Beitz
A structured approach to design with clear
phases and decision points.
3 Ohsuga
A model focusing on the cognitive aspects of
design and problem-solving.
4 Earle
A design process model emphasizing creativity
and innovation.

Engineering Design Process Overview
The Engineering Design Process is the formulation of a plan to help an engineer build a product with a specified
performance goal. This process involves a number of steps, and parts of the process may need to be repeated
many times before production of a final product can begin.
It is a decision making process (often iterative) in which the basic sciences, mathematics, and engineering
sciences are applied to convert resources optimally to meet a stated objective. Among the fundamental elements
of the design process are the establishment of objectives and criteria, synthesis, analysis, construction, testing
and evaluation.

Engineering Design Process Steps
1
Research
Gathering information about the problem and
existing solutions
2 Conceptualization
Generating ideas and potential solutions
3
Feasibility Assessment
Evaluating if concepts are technically and
economically viable
4 Establishing Design Requirements
Defining specifications and constraints
5
Preliminary Design
Creating initial designs that meet requirements
6 Detailed Design
Developing complete specifications for the
final product
7
Production Planning
Preparing for manufacturing with tool design
8 Production
Manufacturing the final product

Ohsuga Design Process
The Ohsuga design process is a comprehensive approach that emphasizes the cognitive aspects of design. As
shown in the image, it includes multiple feedback loops and iterative steps to ensure the design meets all
requirements and constraints.

Conceptual Design
Conceptual design is a process in which we initiate the design and come up with a number of design concepts
and then narrow down to the single best concept. This involved the following steps:
Identification of Customer Needs
The main objective of this is to completely understand the customers' needs and to communicate
them to the design team.
Problem Definition
The main goal of this activity is to create a statement that describes what all needs to be
accomplished to meet the needs of the customers' requirements.
Gathering Information
In this step, we collect all the information that can be helpful for developing and translating the
customers' needs into engineering design.
Conceptualization
In this step, broad sets of concepts are generated that can potentially satisfy the problem statement.
Concept Selection
The main objective of this step is to evaluate the various design concepts, modifying and evolving
into a single preferred concept.

Embodiment Design
It is a process where the structured development of the design concepts takes place. It is in this phase that
decisions are made on strength, material selection, size shape and spatial compatibility. Embodiment design is
concerned with three major tasks - product architecture, configuration design, and parametric design.
Product Architecture
It is concerned with dividing the
overall design system into small
subsystems and modules. It is in
this step we decide how the
physical components of the
design are to be arranged in
order to combine them to carry
out the functional duties of the
design.
Configuration Design
In this process we determine
what all features are required in
the various parts/components
and how these features are to
be arranged in space relative to
each other.
Parametric Design
It starts with information from
the configuration design
process and aims to establish
the exact dimensions and
tolerances of the product. Also,
final decisions on the material
and manufacturing processes
are done if it has not been fixed
in the previous process. One of
the important aspects of
parametric designs is to
examine if the design is robust
or not.

Detail Design
It is in this phase the design is brought to a state where it has the complete engineering description of a tested and
a producible product. Any missing information about the arrangement, form, material, manufacturing process,
dimensions, tolerances etc of each part is added and detailed engineering drawing suitable for manufacturing are
prepared.

Models of the Design Process
Designers have to:
Explore
The problem territory
Generate
Solution concepts
Evaluate
Alternative solution concepts
Communicate
A final proposal

Ohsuga Model in Detail
The Ohsuga model provides a detailed framework for the design process, emphasizing the cognitive aspects of
design and problem-solving. As shown in the image, it includes multiple feedback loops and iterative steps to
ensure the design meets all requirements and constraints.

Morphology of Design
Morphology design refers to the
study of the chronological
structure of design projects. It is
defined by seven phases and
their sub steps. Out of seven
phases, the first three phases
belong to the design the
proposed by asimow and the
remaining four phases belong to
production, distribution,
consumption and retirement.
1 Feasibility Study
Initial assessment of
project viability
2 Preliminary Design
Developing initial
concepts
3 Detailed Design
Creating complete
specifications

Concurrent Engineering Design
Concurrent Engineering is an approach to product development that brings together various disciplines to work in
parallel rather than in sequence. This approach helps reduce time to market and improve product quality by
considering all aspects of the product lifecycle simultaneously.

Sequential and Concurrent Engineering
With today's marketplace becoming more and more competitive, there is an ever-increasing pressure on
companies to respond quickly to market needs, be cost effective, reduce lead-times to market and deliver
superior quality products.
Traditionally, design has been carried out as a sequential set of activities with distinct non-overlapping phases. In
such an approach, the life-cycle of a product starts with the identification of the need for that product. These
needs are converted into product requirements which are passed on to the design department.

Sequential Engineering
Process
In sequential engineering, the designers design the product's form, fit,
and function to meet all the requirements, and pass on the design to the
manufacturing department. After the product is manufactured it goes
through the phases of assembly, testing, and installation.
This type of approach to life-cycle development is also known as 'over
the wall' approach, because the different life-cycle phases are hidden or
isolated from each other. Each phase receives the output of the
preceding phase as if the output had been thrown over the wall.

Limitations of Sequential
Engineering
In a sequential engineering approach, the manufacturing department,
for example, does not know what it will actually be manufacturing until
the detailed design of the product is over. This can lead to inefficiencies,
delays, and increased costs due to late-stage design changes.

Over the Wall Engineering
The "over the wall" approach to product development is characterized by departments working in isolation, with
each department completing its work before passing it on to the next department. This can lead to communication
gaps and inefficiencies in the product development process.

Sequential Engineering Workflow
1
Design
Product is designed without input from
manufacturing
2 Manufacturing
Manufacturing receives completed design and
must adapt to it
3
Assembly
Assembly department receives manufactured
parts
4 Testing
Product is tested after assembly is complete
5
Customer
Product is delivered to customer

Comparison Between Sequential and
Concurrent Engineering
Product development cost Higher due to late changes Lower due to early integration
Number of design changes More changes late in process Fewer changes, addressed
earlier
Lead time for product
development
Longer sequential timeline Shorter parallel timeline
Customer satisfaction Lower, needs may change Higher, faster to market
Coordination between
departments
Limited, "over the wall" Extensive, collaborative

Benefits of Concurrent
Engineering
Reduced Time to Market
Parallel activities shorten development cycle
Lower Development Costs
Fewer late-stage changes and rework
Improved Product Quality
All aspects considered from the beginning
Better Team Collaboration
Cross-functional teams work together

Concurrent Engineering
Implementation
Implementing concurrent engineering requires a shift in organizational
culture and processes. Cross-functional teams must be established, and
communication channels must be opened between different
departments. Tools and technologies that facilitate collaboration and
information sharing are essential for successful implementation.

Role of Computers in Design
Computers play a crucial role in modern design processes, enabling
designers to create, analyze, and optimize designs more efficiently.
Computer-aided design (CAD) systems provide powerful tools for
creating accurate and detailed models of products, while simulation and
analysis software help evaluate performance before physical prototypes
are built.

CAD System Architecture
CAD system architecture consists of several components that work together to provide a comprehensive design
environment. These components include hardware, software, and databases that store design information.

Roles of CAD in Design
Accurate Graphical Representation
Accurately generated and easily modifiable
graphical representation of the product.
Virtual Prototyping
User can nearly view the actual product on the
screen, make any modification to it and present
his ideas on screen without any prototype,
especially during the early stages of the design
process.
Complex Design Analysis
Complex design analysis in short time. By
implementing Finite Element Analysis (FEA)
methods user can perform static, dynamic &
natural frequency analysis, heat transfer
analysis, fluid flow analysis, and plastic
analysis.
Information Management
It records and recalls information with
consistency and speed. Use of Product Data
Management (PDM) systems can store the
whole design and processing history of a
certain product for future reuse and upgrade.

3D Drawing Capabilities
Modern CAD systems provide powerful 3D drawing capabilities that
allow designers to create detailed and accurate models of products.
These models can be viewed from any angle, sectioned to reveal
internal details, and used for various analyses and simulations.

Application of Computers to Design
Modeling of the Design
Creating digital representations of products
Engineering Design and Analysis
Simulating performance and behavior
Evaluation of Prototype through
Simulation and Testing
Virtual testing before physical prototyping
Drafting and Design Documentation
Creating detailed drawings and specifications

Benefits of CAD
Productivity Improvements
Productivity improvement in design depends on:
Complexity of drawing
Degree of repetitiveness of features in the
designed parts
Degree of symmetry in the parts
Extensive use of library of user defined shapes
and commonly used entities
Additional Benefits
Shorter Lead Times
1.
Flexibility in Design
2.
Design Analysis
3.
Fewer Design Errors
4.
Standardization of Design, Drafting and
Documentation
5.
Drawings are more understandable
6.
Improved Procedures of Engineering Changes
7.

Benefits of CAD in Manufacturing
Tool and Fixture Design
Design of tools and fixtures for manufacturing
processes
Process Planning
Computer aided process planning for efficient
production
Documentation
Preparation of assembly lists and bill of
materials
Inspection
Computer aided inspection for quality control
Component Management
Coding and classification of components
Production Control
Production planning and control systems
CNC Programming
Preparation of numerical control programs for
manufacturing the parts on CNC machines
Assembly Planning
Assembly sequence planning for efficient
production

Reasons for Implementing CAD
4
Increase Productivity
To increase the productivity of
the designer
Improve Quality
To improve the Quality of Design
Better Documentation
To improve Documentation
Create Database
To create a Database for
manufacturing

Computer Graphics
Computer Graphics is defined as creation, storage, and manipulation of pictures and drawings by means of a
digital computer. It is an extremely effective medium for communication between people and computers.
Computer graphics studies the manipulation of visual and geometric information using computational techniques.
It focuses on the mathematical and computational foundations of image generation and processing rather than
purely aesthetic issues.

Interactive Computer Graphics
In Interactive Computer Graphics (ICG) the user interacts with the computer and comprises the following
important functions:
A coordinate system is one which uses one or more numbers, or coordinates, to uniquely determine the position
of a point or other geometric element on a manifold such as Euclidean space.

CAD System Architecture
Components
It is an early model which was used for the basic geometry construction
and modelling purpose. Four major components of CAD System
Architecture are:
1 Database
Stores design information and models
2 Operating System
Manages hardware and software resources
3 Input/Output Devices
Allows user interaction and displays results
4 User Interface
Facilitates communication between user and system

Computer Graphics
Technology
Computer graphics is a technology which uses the display of the
drawing or the geometric model of the component in CAD. CG may be
defined as the process of creation, storage and manipulation of
drawings and pictures with aid of a computer.

Types of Computer Graphics
Passive Computer Graphics
In passive computer graphics, the user cannot interact
with the displayed image. The image is generated and
displayed without any real-time manipulation
capabilities.
Interactive Computer Graphics
In interactive computer graphics, the user can interact
with and manipulate the displayed image in real-time.
This allows for dynamic visualization and modification
of designs.
The following functions of the ICG:
Modelling
Storage
Manipulation
Viewing

Advantages of Computer Graphics
3D Representation
The object drawings can be denoted by its geometric model in three dimensions. i.e. X, Y, Z coordinates.
Accuracy
Accurate drawings can be made.
Sectional Views
Sectional drawings can be easily created.
Easy Modification
Modification of geometric model of objects is easy.
Storage and Retrieval
It is easy storage and retrieval of drawings.

Applications of Computer Graphics
Paint Programs
Digital art creation and image editing
Design Programs
Product and architectural design tools
Presentation Graphics
Creating visual aids for presentations
Animation Software
Creating moving images and visual effects
CAD Software
Engineering and product design tools
Desktop Publishing
Layout and design of printed materials
Education and Training
Visual learning tools and simulations
Image Processing
Manipulation and analysis of digital images

Coordinate Systems:
Number Line
The simplest example of a coordinate system is the identification of
points on a line with real numbers using the number line. In this system,
an arbitrary point O (the origin) is chosen on a given line. The coordinate
of a point P is defined as the signed distance from O to P, where the
signed distance is the distance taken as positive or negative depending
on which side of the line P lies. Each point is given a unique coordinate
and each real number is the coordinate of a unique point.

Cartesian Coordinate
System
The Cartesian coordinate system is a fundamental coordinate system
used in computer graphics and CAD. It uses perpendicular axes to
define points in space. In 2D, points are represented as (x,y), while in
3D, points are represented as (x,y,z).

Polar Coordinate System
Another common coordinate system for the plane is the polar coordinate system. A point is chosen as the pole
and a ray from this point is taken as the polar axis. Points are defined by their distance from the pole (radius) and
the angle from the polar axis.

Cylindrical and Spherical Coordinates
In addition to Cartesian and polar coordinates, cylindrical and spherical coordinate systems are also used in 3D
modeling and computer graphics. These systems are particularly useful for objects with cylindrical or spherical
symmetry.

Windowing Transformation
When it is necessary to examine in detail a part of a picture being
displayed, a window may be placed around the desired part and the
windowed area magnified to fill the whole screen and multiple views of
the model may also be shown on the same screen.
The window is a rectangular frame or boundary through which the user
looks onto the model. The viewport is the area on the screen in which
the contents of the window are to be presented as an image.

Clipping Transformation
Clipping is the process of removing parts of a line or polygon that are outside the viewing area. This is an
important operation in computer graphics as it helps optimize rendering by only processing visible elements.

2D Transformations
1 Scaling
Changing the size of an object
P =
2
[X , Y ] =
2 2
[S ×
x X, S ×
y Y ]
[P ] =
2
[
Sx
0
0
Sy
] [
x
y
]
2 Translation
Moving an object to a new position
[P ] =
2
[T ] ç
x [P]
3 Reflection with Mirror
Creating a mirror image of an object
4 Rotation
Rotating an object around a point

Translation Transformation
It is the most common and easily understood transformation in CAD. This moves a geometric entity in space in
such a way that the new entity is parallel at all points to the old entity. A representation is shown in following figure
for an object. Let us now consider a point on the object, represented by P which is translated along X and Y axes
by dX and dY to a new position P'. The new coordinates after transformation are given by following equations.
[P ] =
2
=
[
x2
y2] [
x + dX
y + dY
]
This can also be written in matrix form as follows.
+
[
x
y
] [
dX
dY
]
This is normally the operation used in the CAD systems as MOVE command.

Reflection or Mirror Transformation
Reflection or mirror is a transformation, which allows a copy of the object to be displayed while the object is
reflected about a line or a plane.

Example for Reflection Transformation
The transformation required in this case is that the axes coordinates will get negated depending upon the
reflection required. For example from following figures, the new
P =
2
[X , Y ] =
2 2
[X, 2Y ]
This can be given a matrix form as
[P ] =
2
[T ] ç
m [P]
Thus the general transformation matrix will be
[M] = [
±1
0
0
±1
]
Here, -1 in the first position refers to reflection about Y-axis where all the X coordinate values get negated. When
the second term becomes -1 the reflection will be about the X-axis with all Y coordinate values getting reversed.
Both the values are -1 for reflection about X and Y-axes.

Rotation Transformation
Rotation is another important geometric transformation. The final position and orientation of a geometric entity is
decided by the angle of rotation (») and the base point about which the rotation, is to be done (following figure).
To develop the transformation matrix for transformation, consider a point P located in XY plane, being rotated in
the counter clockwise direction to the new position, P' by an angle » as shown in following figure, The new
position P' is given by P' = [x', y'].

Rotation Transformation Equations
From the following figure, the original position is specified by
x = r cos ³
y = r sin ³
The new position, P' is specified by
x =
2
r cos(³ + ») = r cos » cos ³ 2 r sin » sin ³ = x cos » 2 y sin »
y =
2
r sin(³ + ») = r sin » cos ³ + r cos » sin ³ = x sin » + y cos »
This can be written in a matrix form as
[P ] =
2
=
[
x2
y2] [
cos »
sin »
2 sin »
cos »
] [
x
y
]
[P ] =
2
[T ] ç
R [P]
[T ] =
R [
cos »
sin »
2 sin »
cos »
]

Homogeneous Coordinates
Homogeneous coordinates are a system of coordinates used in projective geometry. They have the advantage
that the equations for translation, rotation, scaling and perspective all become linear transformations when
formulated in homogeneous coordinates.
[P ] =
2
=
x2
y2
1
1
0
0
0
1
0
dX
dY
1
x
y
1
[MT] =
1
0
0
0
1
0
dX
dY
1

Viewing Transformations
Displaying an image of a picture involves in mapping the co-ordinates of the picture into the appropriate
coordinates on the device where the image is to be displayed. This process involves several transformations to
convert from world coordinates to device coordinates.

Elements of CAD System
Functional Areas of a CAD Design Process
The various functional areas that make up a CAD system
Geometric Modelling
Creating digital representations of physical objects
Design Analysis and Optimization
Evaluating and improving designs
Design Review and Evaluation
Assessing designs against requirements
Documentation and Drafting
Creating technical drawings and specifications

Manufacturing Control Applications of CAM
The manufacturing control applications of CAM are concerned with developing computer systems for
implementing the manufacturing control function.
The important manufacturing planning applications of CAM includes:
Process Monitoring and
Control
Real-time monitoring and control of
manufacturing processes
Quality Control
Ensuring products meet quality
standards
Shop Floor Control
Managing and optimizing shop floor
operations
Inventory Control
Managing raw materials and
finished goods
Just in Time Production
Implementing JIT production
systems

Computer Integrated Manufacturing (CIM)
CAD+CAM = CIM
CIM is the total integration of all components involved in converting raw materials into finished products and
getting the products to the market.
CIM is the integration of the total manufacturing enterprise through the use of integrated systems and data
communications coupled with new managerial philosophies that improve organisational and personnel efficiency.

Types of Production Systems: Job Shop
Production
Job or unit production involves the manufacturing of a single complete unit as per the customer's order. This is a
special order type of production. Each job or product is different from others and no repetition is involved.
Three types of job production:
A small number of pieces produced once
A small number of pieces produced intermittently when the need arises
A small number of pieces produced periodically at known time intervals

Batch Production
In this type, the products are made in small batches and in large variety. Each batch contains identical items but
every batch is different from the others.
Three types of batch production are:
A batch produced only once.
A batch produced repeatedly at irregular intervals, when the need arises.
A batch produced periodically at known intervals, to satisfy continuous demand.

Mass Production
In this type of production, only one type of product or maximum 2 or 3
types are manufactured in large quantities. Standardisation of products,
process, materials, machines and uninterrupted flow of materials are the
basic features of this system. Mass production system offers economics
of scale as the volume of output is large.

Process or Continuous Production
This type of production is used for manufacture of those items whose demand is continuous and high. Here single
raw material can be transformed into different kind of products at different stages of production processes. E.g.,
in processing of crude oil in refinery one gets kerosene, gasoline, etc., at different stage of production.
The characteristics, merits and demerits of continuous production system are the same as that of the mass
production system.
Suitability: the industries like paper, textiles, cement, chemicals, automobiles, etc., are a few examples of
continuous production industries.

Production System Comparison
Volume Very low Low to medium High Very high
Variety Very high High Low Very low
Flexibility Very high High Low Very low
Cost per unit Very high High Low Very low
Skill level Very high High Medium Low

Manufacturing Models and Metrics
Definition
Manufacturing metrics are used to quantitatively
measure the performance of the production facility
or a manufacturing company. Manufacturing
metrics is a system of related measures that
facilitates the quantification of some particular
characteristics of production.
Why Use Manufacturing Metrics?
To track performance of the production system
in successive periods.
To determine the merits, and demerits of the
potential new technologies and system.
To compare alternative methods
To make good decisions

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