The document discusses different design processes and models, including: 1. Shigley's model which involves identifying problems in existing products, developing designs to meet requirements, analyzing each design, selecting the optimum one, developing a prototype, and producing documentation. 2. Pahl and Beitz's model which involves clarifying the task, abstracting the problem, finding working principles, embodying the solution, and detailing the design. 3. Ohsuga's model which involves clarifying objectives and constraints, conceptual design, preliminary design, detailing design, and evaluation.

1. DESIGN PROCESS

2. CONTENTS
• INTRODUCTION
• CAD DEFINITION
• DESIGN PROCESS - SHIGLEY
• DESIGN PROCESS - PAHL AND BEITZ
• DESIGN PROCESS - OSHUGA

3. INTRODUCTION – WHAT IS DESIGN ?
• Design is a creative
planning process that leads
to useful products and
systems.
• There is no perfect design.
• Requirements of a design
are made up of
criteria and constraints.

4. What is the Design Process ?
• The design process is a purposeful method of
planning practical solutions to problems.
• The design process is never final; there are always
multiple solutions to a problem.
• The design process is influenced by requirements
called criteria and constraints.

5. Computer-Aided Design (CAD)
• A software system that uses computer graphics to
assist in the creation, modification, and analysis of
a design.

6. Computer-Aided Design Process
• Two types of activities: synthesis and
analysis
• Synthesis is largely qualitative and hard to
capture on computer
• Analysis can be greatly enhanced with
computers
• Once analysis is complete, then design
evaluation- rapid prototyping
• Software packages for design optimization

7. HOW DOES IT WORK?
• Geometric modeling - Uses basic lines, curves, and
shapes to generate the geometry and topology of a part
– 2D -Technical drawing , General-Purpose drafting
– 3D - Difficult to master , Freely rotate and zoom a model
• Automated drafting and documentation
-Produces engineering drawings directly from the CAD
database
– More advanced documentation merges text and graphics
to produce assembly drawings, bills of material,
instruction manuals and reports, parts catalogs, and sales
brochures

8. Advantages & Disadvantages
• Reduce the lead time for new product introduction
• Products can be tested more quickly
• Costly mistakes in design or production can be avoided
• Time to manufacture can be reduced
• Documentation can be printed in various forms for
multiple users
• The quality of designs and the products manufactured from
them is improved
• Incompatibility
• Complex Surfaces

9. THE DESIGN PROCESS
In recent years there have been several attempts to
provide a formal description of the stages or elements
of the design process.
• The models of the design profess
1. Shighely Model
2. Pahl and Beitz
3. Ohsuga

10. Shighely Model
The problems in the existing products
The problem in the existing product or
specification of the new product
The designer develops number of
designs to meet the requirement
Each design from the synthesis stages are
Analysed and optimum one is selected.
A prototype of the product is developed
and experimentally checked for Its
performance, quality, reliability and other
aspects of product
After the product design passing through
the evaluation stage, drawings
diagrams,material specification,
assembly lists, bill of materials etc.

11. Pahl and Beitz Model

12. Ohsuga Model