The engineering design process involves several iterative steps: 1) Recognizing customer needs and wants and defining design requirements and goals. 2) Developing preliminary design concepts and analyzing them to ensure they meet requirements. 3) Applying decision processes to select the best design concept that meets requirements and is superior regarding goals. 4) Product development involves tooling, fabrication, testing, and may require redesign. 5) The design process is usually a team effort involving different engineering and business functions.

1. Engineering Design
Overview
Dr. C.V. Suresh Babu

7. THE ENGINEERING DESIGN
PROCESS
Focus herein will be on product design, however much of what is
presented is just as applicable to the design of processes
The design process is often combined/confused with product
development - it is difficult to distinguish where design ends and
development begins
Stages/phases in the design/development process begin with
recognition of customer needs/wants through to production (first
article)

8. RECOGNITION OF
NEEDS/WANTS
The needs/wants are subjective and dependent on the customer
(consumer, company, government)
How does one become aware of the needs/wants? - marketing,
publications ongoing customer relationships, ...

9. DETERMINATION OF DESIGN
CONCERNS
Design concerns are defined by the customer and consist of design
requirements (needs) and design goals (wants)
The engineer must translate, what is often times, qualitative
needs/wants of the customer into quantitative and measurable design
requirements and goals
Distinction between design requirements and design goals
◦ design requirements - must be met for the design to be considered a
possible solution (yes or no)
◦ design goals - features desirable in the design - the closer the design is to
achieving the goals the better the design (better or worse)

10. IN THE DESIGN OF A BICYCLE
Design requirement - strength: The bike must support the weight of the
rider (with a reasonable factor of safety) without failing. The rider
doesn't care if the bike can support twice that weight. All the rider
cares about is that the bike doesn't break when he/she rides it. The
rider will not look upon the design which is able to support twice
his/her weight with any additional favor.
Design goal - weight: The bike should be lightweight. Given everything
else is the same, if one bike weighs 20 lb and another bike weighs 15 lb,
the rider will prefer the design which weighs 15 lb

11. CAN A DESIGN CONCERN BE BOTH
A REQUIREMENT AND A GOAL?
Although not typical, a design concern may be both a requirement and
a goal
◦ a product may have specific regulations governing a design concern (a design
requirement), however, for that same design concern the customer may
desire the product go beyond the regulation (a design goal)
◦ i.e. automobile crash safety

12. THE BEST SOLUTION
A possible solution to a design problem meets all of the design
requirements
The one possible solution which is superior with respect to the design goals
is the best solution
There can be many possible solutions to a design problem, but only one of
those possible solutions is the best solution
The best solution will be the design of choice (will be the one selected by
the customer, will receive the contract award in an industry setting)

13. unacceptable solutions
do not comply with all design requirements
possible solutions
comply with all design requirements
best solution
complies with all design requirements
superior with respect to design goals

14. THE NEXT THREE STEPS IN THE
DESIGN PROCESS ARE ITERATIVE
AND THE ORDER MAY BE ALTERED
Development of preliminary design concepts
Perform analyses (confirm the design concepts comply with the design
requirements and quantify the design concepts with respect to the
design goals)
Application of some decision theory/process to determine which design
concept is the best solution
◦ in order to be considered as a possible solution, the design concept must
comply with all the design requirements, therefore the decision process is
applicable only to the design goals
◦ the decision process can take the form of a simple matrix where the
performance of each of the design concepts with respect to the design goals
is compared

15. The analyses may lead to revision of the design concepts or possibly,
some combining of design concepts. If that is the case, then the revised
design concepts would need to be analyzed and so on. It may be
preferable to do some evaluation (application of a decision process)
right after development of the design concepts in order to reduce the
amount of detailed analyses necessary.
The design of choice is the one which meets the design requirements
and is superior with respect to the design goals

16. PRODUCT DEVELOPMENT
PROCESS
Stages of product development include:
◦ product CAD files
◦ design tooling, tooling CAD files, and fabrication
◦ fabrication process definition
◦ quality assurance plan (inspection plan, testing plan)
◦ fabrication of tool proof/process verification unit
◦ inspection
◦ fabrication of qualification test unit
◦ qualification testing
◦ fabrication of first article unit
◦ production
At stages in the product development process, redesign of the product
may be necessary
Many stages are done concurrently, rather than sequentially

17. STEPS IN THE DESIGN/DEVELOPMENT
PROCESS ARE USUALLY CARRIED OUT IN
A TEAM ENVIRONMENT
The team should include representation from various functions including:
product engineering, manufacturing engineering, production, quality control,
marketing, program management
Responsibilities/contribution to the design/development by each function:
◦ product engineering: product design, CAD, analysis, …
◦ manufacturing engineering: fabrication process, tooling design, CAD, …
◦ production: fabrication of the product
◦ quality control: qualification testing, inspection, acceptance testing, …
◦ marketing: customer insight (greatest awareness of customer desires)
◦ program management: budget, schedule, …