Subject: Quality Function Deployment
Group Members:
Fatma CEYLAN
Ceren KİMSESİZ
Deniz AKGÜN
Simay ÇETİN
Ahmet ÖZTÜRK
Quality Function Deployment
To design a product well, a design teams needs to know what it is they are
designing, and what the end-users will expect from it. Quality Function Deployment is
a systematic approach to design based on a close awareness of customer desires,
coupled with the integration of corporate functional groups. It consists in translating
customer desires (for example, the ease of writing for a pen) into design characteristics
(pen ink viscosity, pressure on ball-point) for each stage of the product development
(Rosenthal,1992).
Ultimately the goal of QFD is to translate often subjective quality criteria into
objective ones that can be quantified and measured and which can then be used to
design and manufacture the product. It is a complimentary method for determining
how and where priorities are to be assigned in product development. The intent is to
employ objective procedures in increasing detail throughout the development of the
product. (Reilly, 1999) Quality Function Deployment was developed by Yoji Akao in
Japan in 1966. By 1972 the power of the approach had been well demonstrated at the
Mitsubishi Heavy Industries Kobe Shipyard (Sullivan, 1986) and in 1978 the first
book on the subject was published in Japanese and then later translated into English in
1994 (Mizuno and Akao, 1994).
In Akao’s words, QFD "is a method for developing a design quality aimed at
satisfying the consumer and then translating the consumer's demand into design targets
and major quality assurance points to be used throughout the production phase. ...
[QFD] is a way to assure the design quality while the product is still in the design
stage." As a very important side benefit he points out that, when appropriately applied,
QFD has demonstrated the reduction of development time by one-half to one-third.
(Akao, 1990)
The 3 main goals in implementing QFD are:
1. Prioritize spoken and unspoken customer wants and needs.
2. Translate these needs into technical characteristics and specifications.
3. Build and deliver a quality product or service by focusing everybody toward
customer
satisfaction.
Quality Function Deployment has helped to transform the way many
companies:
• Plan new products
• Design product requirements
• Determine process characteristics
• Control the manufacturing process
• Document already existing product specifications
QFD uses some principles from Concurrent Engineering in that cross-functional
teams are involved in all phases of product development. Each of the four phases in a
QFD process uses a matrix to translate customer requirements from initial planning
stages through production control (Becker Associates Inc, 2000). Each phase, or
matrix, represents a more specific aspect of the product's requirements. Relationships
between elements are evaluated for each phase. Only the most important aspects from
each phase are deployed into the next matrix.
Phase 1, Product Planning: Building the House of Quality. Led by the marketing
department, Phase 1, or product planning, is also called The House of Quality. Many
organizations only get through this phase of a QFD process. Phase 1 documents
customer requirements, warranty data, competitive opportunities, product
measurements, competing product measures, and the technical ability of the
organization to meet each customer requirement. Getting good data from the customer
in Phase 1 is critical to the success of the entire QFD process.
Phase 2, Product Design: This phase 2 is led by the engineering department. Product
design requires creativity and innovative team ideas. Product concepts are created
during this phase and part specifications are documented. Parts that are determined to
be most important to meeting customer needs are then deployed into process planning,
or Phase 3.
Phase 3, Process Planning: Process planning comes next and is led by manufacturing
engineering. During process planning, manufacturing processes are flowcharted and
process parameters (or target values) are documented.
Phase 4, Process Control: And finally, in production planning, performance
indicators are created to monitor the production process, maintenance schedules, and
skills training for operators. Also, in this phase decisions are made as to which process
poses the most risk and controls are put in place to prevent failures. The quality
assurance department in concert with manufacturing leads Phase 4.
QFD analysis works in the following stages:
(i) Determine the customer requirements (CR’s). These are stated as customer/user
characteristics, e.g. faster, smaller, lighter, better sounding, different color, ….
(ii)
Prioritize the customer demands (based on statistical analysis of customer
surveys).
(iii) Translate the customer needs into technical specifications, i.e. measurable
engineering requirements. The tech specs are also called technical parameters (TP’s).
(iv) Complete the relationship matrix: the goal is to associate which technical
features of the product have an effect on (or contribute towards) each need of the
customers.
(v)
Benchmarking, or analyzing competing products: rank the competing products
in terms of customer satisfaction and technical performance.
(iv) Rank relative technical difficulty of achieving each technical specification.
(vii) Complete the ‘roof’: identify the inter-relations between different TP’s. Note that
increasing one requirement may increase, have no effect on, or decrease one or more
design requirements. Thus, achieving a given design requirement may require some
conflict resolution (i.e. design modification, or optimization).
(viii) Determine the engineering specification target values. This is based on
customer requirements as well as on the values for the benchmarked products.
(ix) Prioritize the requirements: the goal is to improve the most critical design issues
first.
The Structure of the “House of Quality”
Example
Figure shows an electrical appliance: an Ice-tea maker. We will use the QFD to
study how to improve its design. The operation is as follows: Add tea leaves to the
steeping basket, and cool water to the tank, and switch on the machine. The water
from the tank enters the heating chamber, where an electrical coil boils it. The
steam pushes the how water through a tube to the steeping basket. The hot water
seeps through the tea leaves, and the tea drips down into the jar. Finally, the icetea is prepared by adding sugar, lemon, and ice to the tea in the jar, and mixing.
Based on surveys, the customer requirements are identified; subsequent analysis of the
surveys yields the relative importance. Based on the engineering analysis of the
design, the corresponding technical features that must be modified are identified.
Usually, for each customer requirement, there will be one or more technical feature.
Also, the correlation between the CR’s and TP’s are noted by marking arrows (UParrow means positively correlated, i.e. increasing the TP value will increase the CR;
DOWN-arrow indicates negative correlation).
NOTES:
1. The correlation between the CR’s and TP’s is shown as number values: 9 means
high correlation, 5 means moderate, and 3 means weak. A blank cell means that the
correlation is negligible (or zero). [Some companies may use different ratings].
2. Meaning of arrows: e.g., if the ‘Time to clean product’ is decreased, then
‘Easy to clean’ rating will increase. Similarly, if the ‘Hottest temperature outside
the container’ is increased, it will decrease the rate of condensation, and more
steam will escape from the machine (i.e. objective of ‘Steam must not escape’ is
decreased).
A good convention is to always write the CR’s in terms so that “higher/more is
better”. In this case, you can interpret the arrows as whether the ideal design wants
to maximize the corresponding TP (UP arrow), or minimize it (DOWN-arrow).
3. Numerical values for relative importance are derived from customer survey
results.
Now we proceed to the next steps: Benchmarking and analysis based on
engineering and technical evaluations of what TP’s we can aim to modify by
changing some design modules.
The technical difficulty of each objective is assigned a numerical rating by the
engineers who are in charge of the design of the modules related to this
parameter. The team also consults each other to standardize their relative ratings.
NOTES:
1. Technical difficulty values are relative numbers assigned by engineering
teams
2. The right hand side shows comparison of consumer preferences to design of
competing products. These numbers are relative, and based on statistics from
customer surveys.
3. The ‘roof’ of the House is completed by identification of inter-related TP’s –
there are four types of inter-relationships of concern, these are described in the
table below.
+
strong positive
+
positive
-
negative
-
strong negative
increase in one will increase the
other by similar amount
increase in one will increase the
other a little
increase in one will decrease the
other a little
increase in one will decrease the
other by similar amount
When there are negative correlations, the re-design will involve some conflict
resolution. This means that either a compromise solution must be found by
formulation and solving of some optimization problem, or some design modules
may need to be re-designed so as to eliminate the conflict.
4. The technical importance is computed as L(relative importance)x(correlation
rating). Thus the importance of “Temperature of water in steeping basket’ =
9x9+2x3 = 87.
How to use the “House of
Quality”
Once the house is completely constructed, it provides a guideline for decisions on
which design features should be modified or upgraded first. If there is
unlimited time and money, we would like to upgrade all the features that can
be technically improved. However, this may not be the best strategy:
(a) A competitor may introduce a new product and capture some of the potential
market while we are trying to improve our product.
(b) It may be better to provide sequential upgrades to tempt earlier users to buy a
new machines once in every few time periods (for example, digital camera
companies used this technique very effectively in the last few years).
Thus, with budget and time constraints, the House of quality provides the design
team with information to prioritize the important (in terms of customer demand)
design changes.
House of Quality
Steps in Understanding the House of Quality
Introduction
Every successful company has always used data and information to help in its
planning processes. In planning a new product, engineers have always examined the
manufacturing and performance history of the current product. They look at field test
data, comparing their product to that of their competitor’s product. They examine any
customer satisfaction information that might happen to be available. Unfortunately, much
of this information is often incomplete. It is frequently examined as individual data,
without comparison to other data that may support or contradict it.
By contrast, Quality Function Deployment (QFD) uses a matrix format to capture
a number of issues that are vital to the planning process. The House of Quality Matrix is
the most recognized and widely used form of this method. It translates customer
requirements, based on marketing research and benchmarking data, into an appropriate
number of engineering targets to be met by a new product design. Basically, it is the
nerve center and the engine that drives the entire QFD process. According to Hauser and
Clausing, it is “a kind of conceptual map that provides the means for interfunctional
planning and communication.”
There are many different forms of the House of Quality, but its ability to be
adapted to the requirements of a particular problem make it a very strong and reliable
system to use. Its general format is made up of six major components. These include
customer requirements, technical requirements, a planning matrix, an interrelationship
matrix, a technical correlation matrix, and a technical priorities/benchmarks and targets
section.
The Voice of the Customer
The initial steps in forming the House of Quality include determining, clarifying,
and specifying the customers’ needs. These steps lay the foundation for a clearly defined
venture and will ensure a project or process is well thought out prior to any further
development.
Clarifying Customer Needs
Customers buy benefits and producers offer features. This seems like a relatively
simple notion, however, unless customers and producers are perfectly in tune with one
another, it may be very difficult to anticipate these features, or each underlying benefit
from each producer. It is of utter importance to translate the wishes of each and every
customer into some tangible values that can be turned into engineering specifications.
Some of theses features include but are not limited to:
Specifying the Customer Needs
After determining what items are most important to the customer, organizations
must translate them into particulate specifications. Nothing can be produced, serviced or
maintained without detailed specifications or some set of given standards. Each aspect of
the desired item must be clearly defined: Measurements must be defined, heights
specified , torques stated, and weights targeted.
These values can be derived from several locations. Organizations can use known
data from market research, or conduct new studies to gather necessary information. In
any event, the needs, which were clarified and then explicitly stated, should be satisfied
to the best of that organization’s ability.
Technical Requirements
The next step of the QFD process is identifying what the customer wants and what
must be achieved to satisfy these wants. In addition, regulatory standards and
requirements dictated by management must be identified. Once all requirements are
identified it is important to answer what must be done to the product design to fulfill the
necessary requirements. Figure 2 explains how to use a requirement chart to help the
design process.
Planning Matrix
The next step in the QFD process is forming a planning matrix. The main purpose
of the planning matrix is to compare how well the team met the customer requirements
compared to its competitors. The planning matrix shows the weighted importance of each
requirement that the team and its competitors are attempting to fulfill. Customer ratings,
typically ranging from 1 to 5, are given to each company under each requirement. The
customer ratings are combined with the weighted performance of each demand to
produce an overall performance measure for the companies. The planning matrix is a part
of the “House of Quality” matrix.
Interrelationship Matrix
The main function of the interrelationship matrix is to establish a connection
between the customer’s product requirements and the performance measures designed to
improve the product. The first step in constructing this matrix involves obtaining the
opinions of the consumers as far as what they need and require from a specific product.
These views are drawn from the planning matrix and placed on the left side of the
interrelationship matrix.
With this customer overview, the company can begin to formulate a strategy to
improve their product. In doing this, the strengths and weaknesses of the company are
weighted against the customer priorities to determine what aspects need to be changed to
surpass the competition, what aspects need to change to equal the competition, and what
aspects will be left unchanged. The optimal combination is desired.
Knowing what improvements need to be made allows the list of performance
measures to be generated and displayed across the top of the interrelationship matrix. By
definition, a performance measure is a technical measure evaluating the product’s
performance of a demanded quality (Terninco). In other words, the company must take
the voice of the customer and translate it into engineering terms. The matrix will have at
least one performance measure for each demanded quality.
After setting up the basic matrix, it is necessary to assign relationships between
the customer requirements and the performance measures. These relationships are
portrayed by symbols indicating a strong relationship, a medium relationship, or a weak
relationship. The symbols in turn are assigned respective indexes such as 9-3-1, 4-2-1, or
5-3-1. When no relationship is evident between a pair a zero value is always assigned.
The interrelationship matrix should follow the Pareto Principle keeping in mind that
designing to the critical 20% will satisfy 80% of the customer desires (Terninco).
Therefore, there should not be a significant number of strong relationships between pairs.
Technical Correlation Matrix
Performance measures in existing designs often conflict with each other. The
technical correlation matrix, which is more often referred to as the Roof, is used to aid in
developing relationships between customer requirements and product requirements and
identifies where these units must work together otherwise they will be in a design
conflict. The following symbols are used to represent what type of impact each
requirement has on the other.
These symbols are then entered into the cells where a correlation has been
identified. The objective is to highlight any requirements that might be in conflict with
each other.
Any cell identified with a high correlation is a strong signal to the team, and
especially to the engineers, that significant communication and coordination are a must if
any changes are going to be made. If there is a negative or strongly negative impact
between requirements, the design must be compromised unless the negative impact can
be designed out. Some conflicts can’t be resolved because they are an issue of physics.
Others can be design-related, which leaves it up to the team to decide how to resolve
them. Negative impacts can also represent constraints, which may be bi-directional. As a
result, improving one of them may actually cause a negative impact to the other.
Sometimes an identified change impairs so many others that it is just simply better to
leave it alone. According to Step-By-Step QFD by John Terninko, asking the following
question when working with this part of the House of Quality helps to clarify the
relationships among requirements: “If technical requirement X is improved, will it help
or hinder technical requirement Z”
Many technical requirements are related to each other so working to improve one
may help a related requirement and a positive or beneficial effect can result. On the other
hand, working to improve one requirement may negatively affect a related requirement
as mentioned above. One of the principal benefits of the Roof is that it flags these
negative relationships so they can be resolved. If these issues aren’t settled satisfactorily,
some aspects of the final product will dissatisfy the customer.
Technical Properties & Tragets
The technical properties matrix uses specific items to record the priorities assigned
to technical requirements. It also provides a technical performance achieved by
competitive products and the degree of difficulty in developing each requirement. The
final output of the matrix is a set of target values for each technical requirement to be met
by the new design. In some cases, organizations are not able to create the most optimum
design because of constraints related to cost, technology, or other related items.
Setting Design Targets & Benchmarks
The customer requirements are distributed across the relationships to the quality
characteristics. This gives an organization prioritized quality characteristics. High priority
quality characteristics usually indicate that working on this technical issue will deliver
great value to the customer. A high quality characteristic weight indicates strong
relationships with high priority demanded quality items.
An organization’s current products can be benchmarked technically with
competitors' products on the high priority quality characteristics. In many cases,
organizations should not be surprised to learn that competitors are better at a given task
or characteristic. QFD assists organizations to identify technical areas and to develop
areas where they can achieve the most cost effective customer satisfaction. Organizations
can then examine the Customer Context for usage concerns that must be accounted for,
and set design target specifications for our quality characteristics. At a minimum, current
performance standards should be maintained.
Conclusion
The House of Quality functions as a living document and a source of ready
reference for related products and future upgrades. While it is a great communication tool
at each step in the process, the matrices are the means and not the end. Its purpose is to
serve as a vehicle for dialogue to strengthen vertical and horizontal communications.
Through customer needs and competitive analysis, the House of Quality helps to
identify the critical technical components that require change. Issues are addressed that
may never have surfaced before. These critical issues are then driven through the other
matrices to identify the critical parts, manufacturing operations, and quality control
measures needed to produce a product that fulfills both customer needs and producer
needs within a shorter development cycle time.
The net effect of all of this is that the items that drive the company’s actions are
driven by the customer’s requirements. There is an increased focus on the customer and
an increased awareness of their wants. Because of this focus, the process leads to
improved customer understanding and the ultimate outcome – a satisfied customer.
House of Quality
QUESTIONS:
Q.1) What are benefits of Using the House of Quality Methodology?
A process that forces conversations about customers’ needs to take place early and
often.
Ensures what is important to the customer becomes important to the design team.
Neutralize the “Voice of the Executives”
Allows proffesionals from different backgrounds to communicate effectively.
Q.2) What is the relation between quality and NPD (new product development)?
In NPD, quality must begin before design, when the business case is being
developed that defines the scope and financial deliverables of the project, who the key
customers are and how they are to be researched, what is the project timeline and what
are the resource and budget constraints, etc.
The only way quality can be assured is for organization functions to work
together from the start.
Q.3) What is the goals of QFD?
 Prioritize spoken and unspoken customer wants and needs.
 Translate these needs into technical characteristics and specifications.
 Build and deliver a quality product or service by focusing everybody toward
customer satisfaction.
Q.4) What are phases of Quality Function Deployment?




Phase 1: Product Planning
Phase 2: Product Design
Phase 3: Process Planning
Phase 4: Process Control
References
Terninko, John; Step-by-Step QFD Customer Driven Product Design; Second Edition, St.
Lucie Press, 1997.
Shillito, Larry M.; Advanced QFD Linking Technology to Market and Company
Needs; John Wiley & Sons, Inc.; 1994.
Day, Ronald G.; Quality Function Deployment-Linking a Company with its Customers;
ASQC Quality Press; 1993.
http://www.shef.ac.uk/~ibberson/QFD-IntroIII.html
http://www.soce.org/papers/crow-qfd/crow-qfd.htm
http://www.proactdev.com/pages/ehoq.htm
http://www.qfdi.org/newsletters/translating_voc_into_true_customer_needs.html
http://www.qfdi.org/newsletters/integrating_qfd_in_phasegate.html
http://www.scpdnet.org/papers/crow-qfd/crow-qfd.htm
http://en.wikipedia.org/wiki/Voice_of_the_customer