Quality Function Deployment (QFD) is a systematic tool used in engineering design to ensure customer needs are met throughout the product development process, consisting of interconnected phases that translate customer requirements into technical specifications. The methodology is graphically represented through a House of Quality (HOQ), which includes various rooms to assess customer requirements, engineering characteristics, relationships, and competition analysis. A case study on redesigning a CD jewel case illustrates the application of QFD, highlighting the importance of customer feedback and design targets.

1. Concept in Engineering Design
QUALITY FUNCTION DEPLOYMENT (QFD)
Quality function deployment (QFD) is a planning and team problem-solving tool that has
been adopted by a wide variety of companies as the tool of choice for focusing a design
team’s attention on satisfying customer needs throughout the product development
process.
The term deployment in QFD refers to the fact that this method determines the
important set of requirements for each phase of Product Development Process (PDP)
planning and uses them to identify the set of technical characteristics of each phase that
most contribute to satisfying the requirements.
QFD is a largely graphical method that aids a design team in systematically identifying all
of the elements that go into the product development process and creating relationship
matrices between key parameters at each step of the process.
the QFD process is made up of four phases that proceed in sequence and are connected
as a chain with the output from each phase becoming the input to the next. The product
planning phase of QFD, called the House of Quality (HOQ), feeds results into the design
of individual parts, giving inputs into the process planning design stage, which become
inputs into the production planning phase of QFD.
Stages in QFD

2. Concept in Engineering Design
THE HOUSE OF QUALITY (HOQ) AND ITS CONFIGURATIONS
(Please crosses verify and compare the CD Jewel case study for better understanding)
ROOM 1: The Customer Requirement (CRs) and their importance ratings are gathered by the
team. It is common to group these requirements into related categories. Also included in this
room is a column with an importance rating for each CR
ROOM 2: Engineering characteristics (ECs) are product performance measures and features
that have been identified as the means to satisfy the CRs. product performance measures
features that have been identified as the means to satisfy the Customer Requirements (CRs)
need to translate the customer requirements into language that expresses the parameters of
interest in the language of engineering ECs include both technical and non-technical parameter
weight, force, velocity, power consumption, color, fragrance, shape etc. The units of ECs and
the improvement direction are also provided here. For instance you may want to improve
performance decrease weight etc. Symbols like ( , ) could be used.
Improvement Direction
Units andECs
Room 2
Engineering Characteristics (ECs)
“Hows”
Room 4
Relationship Matrix
“What related to Hows”
Room 5
Importance Ranking
Room 7
Technical Assessment
Room 8
Target Values
Room 3
Correlation Matrix
Importance
Rating
Room 1
Customer
Requirement
(CRs)
“Whats”
Room 6
Customer Assessment
of Competing Products
Rating Competitors on
“Whats”

3. Concept in Engineering Design
ROOM 4: The Relationship matrix is at the center of an HOQ. It is created by the intersection of
the rows of CRs with the columns of ECs. Each cell in the matrix is marked with a symbol that
indicates the strength of the causal association between the EC of its column and the CR of its
row. The coding scheme for each cell is given as a set of symbols that represent an exponential
range of numbers (e.g., 9, 3, 1, and 0). To complete the Relationship Matrix systematically, take
each EC in turn, and move down the column cells row by row, asking whether the EC will
contribute to fulfilling the CR in the cell’s row significantly (9), moderately (3), or slightly (1).
The cell is left blank if the EC had no impact on the CR.
ROOM 5: The Importance Rating: The main contribution of the HOQ is to determine which ECs
are of critical importance to satisfying the CRs listed in Room 1. Those ECs with the highest
rating are given special consideration for these are the ones that have the greatest effect upon
customer satisfaction.
ROOM 3: The Correlation Matrix or Roof of the House of Quality : The correlation matrix,
Room 3, records possible interactions between ECs for future trade-off decisions. The
correlation matrix shows the degree of interdependence among the engineering characteristics
in the “roof of the house.” It is better to recognize these coupling relationships early in the
design process so that appropriate trade-offs can be made. Keep some symbols something of
the following type and bring the relationship between the engineering characteristics (ECs)
parameters.
ROOM 6: Assessment of Competitor’s Products in House of Quality : The data available from
the HOQ can be augmented by adding the results of any benchmarking activities conducted for
the product. This table displays how the top competitive products rank with respect to the
customer requirements listed across the HOQ in Room 2. This information comes from direct
customer surveys, industry consultants, and marketing departments. it is not unusual to have
sparse data on some of the competitors and very detailed data on another. Certain competitors
are targets for new products and, therefore, are studied more closely than others.
ROOM 7 : Technical Assessment : may also include a technical difficulty rating that indicates
the ease with which each of the engineering characteristics can be achieved. Basically, this
comes down to an estimate by the design team of the probability of doing well in attaining
++ Strong Positive
+ Positive
None
– Negative
– – Strong Negative

4. Concept in Engineering Design
desired values for each EC. Again, a 1 is a low probability and a 5 represents a high probability
of success
ROOM 8: Setting Target Values for Engineering Characteristics: is the final step in constructing
the HOQ. By knowing which are the most important ECs (Room 5), understanding the technical
competition (Room 7), and having a feel for the technical difficulty (Room 7), the team is in a good
position to set the targets for each engineering characteristic. Setting targets at the beginning of the
design process provides a way for the design team to gauge the progress they are making toward
satisfying the customer’s requirements as the design proceeds.
CASE STUDY – CD JEWEL CASE
A Group of designers intended to redesign a CD Jewel Case
• Method preferred – Semantic Enquiry + A Simple articulated method
• Based on complaints from the suppliers, Customers, Retailers the design
improvement is required on
• Crack Resistance
• Scratch Resistance
• Color Weight
• Mechanism
• Easy in operation
• Miscellaneous issues
Design of Question to the customer
• Do not use jargon or sophisticated vocabulary.
• Focus very precisely. Every question should focus directly on one specific topic.
• Use simple sentences. Two or more simple sentences are preferable to one compound
sentence.
• Do not lead the customer toward the answer you want
• Avoid questions with double negatives because they may create misunderstanding.
• In any list of options given to the respondents, include the choice of “Other” with a space
for a write-in answer.

5. Concept in Engineering Design
• Always include one open-ended question. Open-ended questions can reveal insights and
nuances and tell you things you would never think to ask.
• The number of questions should be such that they can be answered in about 15 (but no
more than 30) minutes.
• Design the survey form so that tabulating and analyzing data will be easy.
• Be sure to include instructions for completing and returning it.
Template: (Semantic + Articulated Method)
EVALUATING CUSTOMER SURVEYS : Ethnographic Studies
• To evaluate the customer responses, we could calculate the average score for each
question, using a 1–5 scale
• Those questions scoring highest would represent aspects of the product ranked highest
in the minds of the customers
• Frequency analysis - Use the customer templates that has 4 and 5 as the parameter
importance for the questions
Customer Information :TEMPLATE FOR CUSTOMER INTERVIEW
Parameter For Analysis
1 = low importance 5 = high importance
Please list any other improvement features you would like to see in a CD case : _____________________
Would you be willing to pay more for a CD if the improvements you value with a 5 or 4 rating are available on
the market ? yes or no : If yes how much you wish to pay __________________________
How many CD’s do you own (approximately) ? _____
1 A more crack-resistant case 1 2 3 4 5
2 A more scratch-resistant case 1 2 3 4 5
3 A hinge that doesn’t come apart 1 2 3 4 5
4 A more colorful case 1 2 3 4 5
5 A lighter case 1 2 3 4 5
6 A streamlined look (aerodynamically sleek) 1 2 3 4 5
7 A case that fits your hand better 1 2 3 4 5
8 Easier opening CD case 1 2 3 4 5
9 Easier extraction of the CD from the circular fastener 1 2 3 4 5
10 Easier to take out leaflet describing contents of the CD 1 2 3 4 5
11 A more secure locking case 1 2 3 4 5
12 A waterproof case 1 2 3 4 5
13 Make the case from recyclable plastic 1 2 3 4 5
14 Make it so cases interlock so they stack on each other without slipping 1 2 3 4 5

6. Concept in Engineering Design
ENGINEERING CHARACTERISTICS (ECs) – HOW (ROOM 2): The following are chosen as ECs
Force to open (lbs / N)
External Dimension (in / m)
CD positioning feature in case (-)
Toughness of case material (in lbf in–3
/ J m–3
)
Hinge design (-)
Shape of the case (-)
CUSTOMER REQUIREMENT (ROOM 1): choose those which has more than 40 % relative
frequency in the Pareto chars
Q.No Number of responses
with 4 and 5 rating
Relative
Frequency
PARETO CHARTBAR CHART FOR RESPONSE
Question numberQuestion number
RelativeFrequencyofResponse,%
RelativeFrequencyofResponse,%

7. Concept in Engineering Design
RELATIONSHIP MATRIX (ROOM 4):
For example : Force to open : = 5 * 3 + 5 * 3 + 4 * 3 + 4 * 9 + 4 * 3
+ 4 * 3 = 102
Find Relative weight out of 100% and give the Rank Order
Give also the improvement direction: Whether you have to
increase or decrease
CORRELATION MATRIX (ROOM 3)
Give interaction between parameters for example as below
++ Strong Positive ;
+ Positive
None
– Negative
– – Strong Negative
Example : strong positive (++) correlation between the hinge design and the force to open the
case
COMPETITOR ASSESSMENT(ROOM 6)
Assessment matrix of Competitors (say competitors A,B,C,D) such as
1 – Poor, 3 – OK, 5 – Excellent is provided.
For instance
• competitor B’s CD case has a high rating for cost and the best crack and scratch
resistance
• but it rates poorly on removal ease of liner notes, ability to be recycled, and
waterproofing
• Sometime we don’t get the data of all the competitors – Best Matrix should have data of
all the competitors
TECHNICAL ASSESSMENT / DIFFICULTY(ROOM 7) AND TARGET VALUES(ROOM 8)
Technical Assessment / Difficulty is given in terms of probability (Probability of Success
1(low) to 5 (high)
Target values : By knowing which are the most important ECs (Room 5), understanding
the technical competition (Room 7), and having a feel for the technical difficulty (Room
7), the team is in a good position to set the targets for each engineering characteristic.

8. Concept in Engineering Design
THE OVERALL HOUSE OF QUALITY
References
1. George E . Dieter and Linda C . Schmidt, Engineering Design, 4th
Edition, McGraw Hill
2009
+
++
+
++ Strong Positive
+ Positive
None
– Negative
– – Strong Negative
Whether you
have to increase
or decrease
Choose
those which
has more
than 40 %
relative
frequency in
the Pareto
Chart