The
design concept for Pugh Method should be passed the absolute filters. There are
some filters that should be passed which are:
Evaluation
based on judgment of feasibility
- of the design. It is included the overall evaluation of the design team as to the feasibility of each concept
- Evaluation based on assessment of technology readiness.
- Evaluation based on go/no-go screening of the customer requirements. After passed the filters 1 and 2, the emphasis shifts to establishing whether it meets customer requirement framed in the QFD and the PDS.
Pugh
Concept Selection Method is a quantitative technique used to rank the
multidimensional options of an option set. It is frequently used in engineering
for making design decisions but can also be used to rank investment options,
vendor options, product options or any other set of multidimensional entities.
A
basic decision matrix consists of establishing a set of criteria upon which the
potential options can be decomposed, scored, and summed to gain a total score
which can then be ranked. Importantly, the criteria are not weighted to allow a
quick selection process.
Advantages
of Pugh Methods
- Finding a “best” design
- Prevents a team from “falling in love”
- With a flawed design or one not meeting
- All design constraints or objectives
- Communication tool; builds consensus
- Based on the “voice of the customer”
- Results in significant cost savings
The
advantage of this approach to decision making is that subjective opinions about
one alternative versus another can be made more objective. Another advantage of
this method is that sensitivity studies can be performed. An example of this
might be to see how much your opinion would have to change in order for a lower
ranked alternative to out rank a competing alternative.
The
Pugh Evaluation Process
Phase
I
1.
Criteria:
The list of evaluation criteria is developed through team discussion. A
benchmark or datum is selected, usually the “best” existing product. If no
comparable product exists, one of the new concepts (selected at random) can
serve as datum.
2.
Design
concepts: Original design concepts are brainstormed by
individual or small teams.
3.
Evaluation
matrix: Each design concept is discussed and evaluated
against the datum. Through the discussion, new concepts emerge; they are needed
to the matrix and evaluated.
4.
Round
1 result: The result of the first round is evaluated, and the
top ranking concept is selected as the datum for the next round. During an
incubation period, the teams improve the original design concepts by borrowing
ideas and components from each other, as well as through additional creative
thinking. Then Steps 3 and $ are repeated with these improved, synthesized
designs.
Phase
II
5.
Better
designs: The weakest design is dropped; the improvement
process is continued for additional round with fewer but increasingly better
concepts. During the process, the strong, surviving concepts are engineered to
more detail; the criteria are expanded and further refined. The weak point of
the concepts is being eliminated. The team gains insight into the entire
problem and solution.
6.
Superior
concept: the process converges to strong consensus concepts
that cannot be overturned by a “better idea’. The team is committed to this
superior design and wants to see it succeed.
Example:
paper cup replaced with Styrofoam cups.
These
are the list of design of cup.
A= Styrofoam cup
B= injection-molded cup with a
handle.
C= paper cup with a cardboard
sleeve.
D= paper cup with a pull-out handle.
E= paper cup with a cellular wall.
Engineering
characteristic that should be on the cups:
- Temperature in the hand
- Temperature of the outside of the cup
- Material environmental effect
- Indenting force of cup wall
- Porosity of cup wall
- Manufacturing complexity
- Ease of stacking the cup
- Ease of use by customer
- Temperature loss of coffee over time
- Estimated cost for manufacturing the cup in large quantities
After the discussions our group decide to eliminate the
design concept D since it has poor
temperature condition compare to the Styrofoam cup (datum). It also has more
complex shape and not easy to use by the customer compare to the Styrofoam cup.
Then in order to choose the best design we move to the
second Pugh Chart by using design concept B as our new datum since it has the
highest number of positives.
B= injection-molded cup with a
handle.
C= paper cup with a cardboard
sleeve.
E= paper cup with a cellular wall.
From the second Pugh Chart, it show that the design concept
C has the highest number of positive and lowest number of negative criteria compare to
the design concept E. Therefore, design of concept C, paper cup with a cardboard sleeve is the selected design.
