QUESTION:
In the search for more environmentally friendly design, paper cups have replaced Styrofoam cups in most fast-food restaurants. These cups are less effective insulators and the paper cups often too hot for the hand. A design team is in search of a better disposable coffee cup. The designs to be evaluated are: (a) a standard Styrofoam cup, (b) a rigid injection-molded cup with a handle, (c) a paper cup with a cardboard sleeve, (d) a paper cup with a pull-out handle, and (e) a paper cup with a cellular wall. These design concepts are to be evaluated with the Styrofoam cup as the datum. 

The engineering characteristics on which the cups are evaluated are:
  1. Temperature in the hand
  2. Temperature of the outside of the cup
  3. Material environmental impact
  4. Indenting force of cup wall
  5. Porosity of cup wall
  6. Manufacturing complexity
  7. Ease of stacking the cups
  8. Ease of use by customer
  9. Temperature loss of coffee over time
  10. Estimated cost for manufacturing the cup in large quantities
Using your knowledge of fast-food coffee cups, use the Pugh concept selection method to select the most promising design.

ANSWER:
Steps in Pugh Concept Selection Method:
  1. Choose the criteria by which the concepts will be evaluated.
  2. Formulate the decision matrix.
  3. Clarify the design concepts.
  4. Choose the datum concept.
  5. Complete the matrix entries.
  6. Evaluate the ratings.
  7. Establish new datum and rerun the matrix.
  8. Examine the selected concept for improvement opportunities.
 Pugh Concept Chart 1
Selected Criteria
Design Concepts
a
b
c
d
e
Temperature in the hand




D
A
T
U
M
+
-
-
-
Temperature of the outside of the cup
S
-
-
-
Material environmental impact
-
+
+
+
Indenting force of cup wall
+
+
+
+
Porosity of cup wall
+
+
+
+
Manufacturing complexity
-
-
-
-
Ease of stacking the cups
-
-
-
+
Ease of use by customer
+
+
-
-
Temperature loss of coffee over time
+
-
-
-
Estimated cost for manufacturing the cup in large quantities       
-
+
+
+
Number of Pluses
5
5
4
5
Number of Minuses
4
5
6
5

Our company decided to eliminate the design concept (d) based on the following reasons:
  1. Poor temperature condition.
  2. Complex shape.
  3. Difficulty for the use by the customer.
Since design concept (b) has the highest advantages when being compared to the Styrofoam cup, it will become the new datum for the next evaluation.

Pugh Concept Chart 2
Selected Criteria
Design Concepts
b
c
e
Temperature in the hand




D
A
T
U
M
+
+
Temperature of the outside of the cup
-
-
Material environmental impact
+
+
Indenting force of cup wall
+
-
Porosity of cup wall
+
+
Manufacturing complexity
+
+
Ease of stacking the cups
+
+
Ease of use by customer
+
-
Temperature loss of coffee over time
-
-
Estimated cost for manufacturing the cup in large quantities       
+
+
Number of Pluses
8
6
Number of Minuses
2
4

From the evaluation, design concept (c) has the highest number of positive and lowest number of negative criteria compare to the design concept (e). Therefore, paper cup with a cardboard sleeve will be the selected design to replace the Styrofoam cup.