1. Design Stages and Prerequisites

2. Machine
A machine is a device, a formulation of
principles, comprising of various elements
arranged together, so as to carry out the
needs of a human being.

3. Building Blocks of a Machine
• Mechanisms
A mechanism is made of a set of moving
parts or links. The moving parts would
have certain constraints, which would
make the outcome predictable.
• Structure
Structures are the fixed parts in case of a
machine. The fixed parts should be properly
restrained or held.

4. Schematic Concept of a Machine

5. Machine Design
To design is to understand the need, to be
creative, and then using the elementary
principles, devising a new improved machine
for accomplishing the requirements of a
human being.
Machine Design is the art of planning or
devising new or improved machines.

6. Design by Drawing
Features:
– The design is well conceived and changes can be easily
done on the drawings.
– The product design if first finalized on drawings and
then the design is released for production.
– The design process and manufacturing process can be
completely isolated and individual components can be
manufactured by different people.
– The record of design in the form of a drawing ensures
new designer does not have to start from scratch to
update it.

7. Basic Procedure in Machine Design

8. (1) Recognition of Problem
“Necessity is the mother of all inventions”

9. (2) Definition of the Problem
Categories:
• Must: These requirements are must in the design
• Must nots: These are the constraints which the
design should not have
• Wants: These are the requirements worth
stating, but are not always feasible to include.
• Don’t Wants: These are the constraints worth
stating, which preferably should not be present in
the design.

10. Other Considerations in Defining a
Problem
• Workshop facilities
• Form and size of the parts
• Selection of materials and sizes
• Economical considerations
• Economy in size of the batch
• Safety in operation

11. (3) Synthesis and Analysis
Synthesis involves giving shape to the system
and the designer is expect to create layouts,
configuration drawings, sketches of important
components, kinematics of linkages,
mechanisms and other details of joining
assembly.

12. (4) Analysis and Optimization
Analysis is concerned with calculating the
behavior of the design by using appropriate
principles of science.
• Type of load and stresses caused by the loads
• Kinematics or study of motion
• Frictional resistance and lubrication

13. (5) Evaluation
Evaluation is the stage wherein the design is
verified. This involves prototypes, and at this
stage the model undergoes vigorous testing to
ensure that it satisfies all the requirements
specified during definition of the problem

14. (6) Presentation
Presentation is the communication of the design to
others.
Presentation is selling the job and it needs convincing
that the design on offer is a reliable and better one.

15. Creativity and Requisites of a Design
Engineer
• Develop a creative attitude
Be confident that you can provide solution
• Vivid imaginations
Why? What if?
• Persistence and hard work
Invention is 95% perspiration and 5%
inspiration
• Open mind and positive thinking
• Suspend one’s judgment
• Set problem boundaries

16. Abilities of a Good Designer
• Good communication skills
• Team player
• Good understanding of fundamental
environmental sciences and manufacturing
processes
• Enthusiastic
• Efficient method of recording of his observations
• Good understanding of legal requirements
(patents and other legal laws)

17. Design of Machine Elements

18. Use of Standards
• Interchangeability of parts
• Easy replacements
• Reduce shock or inventory
• Better efficiency and specified quality
• Mass production of components

19. Reference:
• Design of Machine Elements 1st Edition by
Farazdak Haideri © 2005 by the Author