QFD uses a series of matrices
to document information collected and developed and represent the team's plan
for a product. The QFD methodology is based on a systems engineering
approach consisting of the following general steps:
- Derive top-level product requirements or technical characteristics
from customer needs (Product Planning Matrix).
- Develop product concepts to satisfy these requirements.
- Evaluate product concepts to select most optimum (Concept
- Partition system concept or architecture into subsystems or assemblies and flow-down higher-
level requirements or technical characteristics to these subsystems or assemblies.
- Derive lower-level product requirements (assembly or part characteristics) and
subsystem/assembly requirements (Assembly/Part Deployment Matrix).
- For critical assemblies or parts, flow-down lower-level product requirements (assembly
or part characteristics) to process planning.
- Determine manufacturing process steps to meet these assembly or part characteristics.
- Based in these process steps, determine set-up requirements, process controls and
quality controls to assure achievement of these critical assembly or part characteristics.
The QFD process described below is supported by our Product
Development Toolkit, which includes QFD software. The matrices and the specific
steps in the QFD process are as follows.
Gather Customer Needs
- Plan collection of customer needs. What sources of information will
be used? Consider customer requirement documents, requests for
proposals, requests for quotations, contracts, customer specification
documents, customer meetings/interviews, focus groups/clinics, user
groups, surveys, observation, suggestions, and feedback from the field.
Consider both current customers as well as potential customers. Pay
particular attention to lead customers as they are a better indicator of
future needs. Plan who will perform the data collection activities and
when these activities can take place. Schedule activities such as
meetings, focus groups, surveys, etc.
- Prepare for collection of customer needs. Identify required information.
Prepare agendas, list of questions, survey
forms, focus group/user meeting presentations.
- Determine customer needs or requirements using the mechanisms
described in step 1. Document these needs. Consider recording any
meetings. During customer meetings or focus groups, ask "why" to
understand needs and determine root needs. Consider spoken needs and
unspoken needs. Extract statements of needs from documents. Summarize
surveys and other data. Use techniques such as ranking, rating, paired
comparisons, or conjoint analysis to determine importance of customer
needs. Gather customer needs from other sources such as customer
requirement documents, requests for proposals, requests for quotations,
contracts, customer specification documents, customer
meetings/interviews, focus groups, product clinics, surveys,
observation, suggestions, and feedback from the field.
- Use affinity diagrams to organize customer
needs. Consolidate similar needs and restate. Organize needs into
categories. Breakdown general customer needs into more specific needs by
probing what is needed. Maintain dictionary of original meanings to
avoid misinterpretation. Use function analysis to identify key unspoken,
but expected needs.
- Once needs are summarized, consider whether to
get further customer feedback on priorities. Undertake meetings,
surveys, focus groups, etc. to get customer priorities. State customer
priorities using a 1 to 5 rating. Use ranking techniques and paired
comparisons to develop priorities.
- Organize customer needs in the Product Planning Matrix. Group under
logical categories as determined with affinity diagramming.
- Establish critical internal customer needs or management control
requirements; industry, national or
international standards; and regulatory requirements. If standards
or regulatory requirements
are commonly understood, they should not be included in order to minimize the
information that needs to be addressed.
- State customer priorities. Use a 1 to 5 rating.
Critical internal customer needs or management
control requirements; industry, national
or international standards; and regulatory requirements, if important enough to
include, are normally given a rating of "3".
- Develop competitive evaluation of current company products and
competitive products. Use surveys,
customer meetings or focus groups/clinics to obtain feedback.
Rate the company's and the competitor's
products on a 1 to 5 scale with "5" indicating that the product fully satisfies
the customer's needs. Include
competitor's customer input to get a balanced perspective.
- Review the competitive evaluation strengths and weaknesses relative to the
customer priorities. Determine the improvement goals and the general strategy
for responding to each customer need. The Improvement Factor is
"1" if there are no planned improvements to the competitive evaluation level.
Add a factor of .1 for every planned step of improvement in the
competitive rating, (e.g., a planned improvement of goiung from a rating
of "2" to "4" would result in an improvement factor of "1.2".
Identify warranty, service, or reliability problems & customer complaints
to help identify areas of improvement.
- Identify the sales points that Marketing will
emphasize in its message about the product. There should be no more than
three major or primary sales points or two major sales points and two
minor or secondary sales points in order to keep the Marketing message
focused. Major sales points are assigned a weighting factor of 1.3 and
minor sales points are assigned a weighting factor of 1.1.
- The process of setting improvement goals and sales points implicitly
develops a product strategy. Formally describe that strategy in a
narrative form. What is to be emphasized with the new product? What are
its competitive strengths? What will distinguish it in the marketplace?
How will it be positioned relative to
other products? In other words, describe the value proposition
behind this product. The key is to focus
development resources on those areas that will provide the greatest value to the customer. This
strategy brief is typically
one page and is used to gain initial focus within the team as
well as communicate and gain concurrence from management.
- Establish product requirements or technical
characteristics to respond to customer needs and organize into logical
categories. Categories may be related to functional aspects of the
products or may be grouped by the likely subsystems to primarily address
that characteristic. Characteristics should be meaningful (actionable by
Engineering), measurable, practical (can be determined without extensive
data collection or testing)and global. By being global, characteristics
should be stated in a way to avoid implying a particular technical solution
so as not to constrain designers. This will allow a wide range of
alternatives to be considered in an effort to better meet customer needs. Identify
the direction of the objective
for each characteristic (target value or range, maximize or minimize).
- Develop relationships between customer needs
and product requirements or technical characteristics. These
relationships define the degree to which as product requirement or
technical characteristic satisfies the customer need. It does NOT show a potential
negative impact on meeting a customer need - this will be
addressed later in the interaction matrix. Consider the goal associated with the
characteristic in determining whether the characteristic satisfies the customer need. Use weights (we recommend using 5-3-1
weighting factors) to indicate the strength of the relationship - strong, medium and
weak. Be sparing with the strong relationships to discriminate the really strong relationships.
- Perform a technical
evaluation of current products and competitive products. Sources of information include:
competitor websites, industry publications, customer interviews, published specifications,
catalogs and brochures, trade shows, purchasing and benchmarking competitorís products,
patent information, articles and technical papers, published benchmarks, third-party
service & support organizations, and former employees.
Perform this evaluation based on the defined product requirements or
technical characteristics. Obtain other relevant data such as warranty or
service repair occurrences and costs.
- Develop preliminary target values for product
requirements or technical characteristics. Consider data gathered during
the technical evaluation in setting target values. Do not get too
aggressive with target values in areas that are not determined to be the primary
area of focus with this development effort.
- Determine potential positive
and negative interactions between product requirements or technical
characteristics using symbols for strong or medium, positive or negative
relationships. Too many positive
interactions suggest potential redundancy in product requirements or technical
characteristics. Focus on negative
interactions - consider product concepts or technology to overcome these
potential trade-offs or consider the trade-off's in establishing target
importance ratings. Multiply the customer
priority rating by the improvement factor, the sales point factor and the
weighting factor associated with the relationship in each box of the matrix and add
the resulting products in each column.
- Identify a difficulty rating (1 to
5 point scale, five being very difficult and risky) for each product requirement or
technical characteristic. Consider technology
maturity, personnel technical qualifications, resource availability,
technical risk, manufacturing capability, supply chain capability, and
schedule. Develop a composite
rating or breakdown into individual assessments by category.
- Analyze the matrix and
finalize the product plan. Determine required actions and areas of focus.
- Finalize target values. Consider the product
strategy objectives, importance of the various technical
characteristics, the trade-offs that need to be made based on the
interaction matrix, the technical difficulty ratings, and technology
solutions and maturity.
- Maintain the matrix as customer needs or
- Develop concept alternatives for the product.
Consider not only the current approach and technology, but other
alternative concept approaches and technology. Use
brainstorming. Conduct literature, technology, and patent
searches. Use product benchmarking to identify different product concepts. Develop
derivative ideas. Perform sufficient definition and
development of each concept to evalaute against the decision criteria determined in
the next step.
- Evaluate the concept alternatives using the
Concept Selection Matrix. List product requirements or technical characteristics from
the Product Planning Matrix down the left side of the Concept
Selection Matrix. Also add other requirements or decision criteria such as key
unstated but expected customer needs or requirements, manufacturability requirements,
environmental requirements, standards and regulatory requirements, maintainability
/ serviceability requirements, support requirements, testability requirements, test
schedule and resources, technical risk, business
risk, supply chain capability, development resources,
development budget, and development schedule.
- Carry forward the target
values for the product requirements or technical characteristics from the
Product Planning Matrix. Add target
values as appropriate for the other evaluation criteria added in the previous
step. Also bring forward the
importance ratings and difficulty ratings associated with each product requirement
or technical characteristic from the Product Planning
Matrix. Normalize the importance rating by
dividing the largest value by a factor that will yield "5" and post this
value to the "Priority" column. Review
these priorities and consider any changes appropriate since these are the
weighting factors for the
decision criteria. Determine the priorities for the additional evaluation criteria added in
the prior step. List concepts across the top of the matrix.
- Perform engineering analysis and trade studies. Rate each
concept alternative against the criteria using a
"1" to "5" scale with "5" being
the highest rating for satisfying the criteria.
- For each rating, multiply the rating by the "Priority" value in that
row. Summarize these values in each column in the bottom row.
The preferred concept alternative(s) will be the one(s) with the highest
- For the preferred concept alternative(s), work to improve the concept
by synthesizing a new concept that overcomes its weaknesses. Focus attention on
the criteria with the lowest ratings for that concept ("1's" and
"2's"). What changes can be made to the design or formulation
of the preferred concept(s) to improve these low ratings with the product
concept? Compare the preferred concept(s) to the other concepts that
have higher ratings for that particular requirement. Are there ways to
modify the preferred concept to incorporate the advantage of another
Subsystem/Subassembly/Part Deployment Matrix
- Using the selected concept as a basis, develop
a design layout, block diagram and/or a preliminary parts list.
Determine critical subsystems, subassemblies or parts. Consider impact
of subsystems, subassemblies or parts on product performance or with
respect to development goals. What parts, assemblies or subsystems
present major challenges or are critical to the success and operation of
the product? What critical characteristics have a major effect on
performance? Consider performing failure mode and effects analysis
(FMEA); failure mode, effects and criticality analysis (FMECA); or fault
tree analysis (FTA) to help pinpoint critical items and their critical
characteristics from a reliability/quality perspective.
- If there will be multiple Subsystem/Subassembly/Part Deployment Matrices prepared,
deploy the technical characteristics and their target values
to the appropriate matrices. Carry forward the important or critical
product requirements or technical characteristics from Product Planning
Matrix (based on importance ratings and team decision) to the
Subsystem/Subassembly/Part Deployment Matrix. These "product needs" become the "what's"
for this next level matrix. Where appropriate, allocate target values
(e.g., target manufacturing cost, mean-time between failures, etc.)
to the Subsystem / Subassembly / Part Deployment Matrices. Organize these
product requirements or technical characteristics by assembly(ies) or part(s) to be addressed on a
particular deployment matrix. Include
any additional customer needs or requirements to address more detailed customer needs
or general requirements. Normalize the
Importance Ratings from the Product Planning Matrix and
bring them forward as the
Priority ratings. Review these priority ratings and make appropriate changes
for the subsystems, subassemblies or parts being addressed. Determine the the Priority for
any needs that were added.
- Considering product requirements or technical
characteristics, identify the critical part, subassembly or subsystem
characteristics. State the characteristics in a measurable way. For higher-level
subsystems or subassembles, state the characteristics in a global
manner to avoid constraining
concept selection at this next level.
- Develop relationships between product needs
(product-level technical characteristics) and the subsystem / subassembly
/ part technical characteristics.
Use 5-3-1 relationship weights for strong, medium and weak
relationships. Be sparing with the strong relationships.
- Develop preliminary target values for subsystem / subassembly / part characteristics.
- Determine potential positive and negative
interactions between the
technical part characteristics using symbols for strong or medium,
positive or negative relationships. Too many positive interactions
suggest potential redundancy in critical
part characteristics. Focus on negative interactions
- consider different subsystem /
subassembly / part concepts, different technologies, tooling concepts, material
technology, and process technology to overcome the potential trade-off or
consider the trade-off in establishing target values.
Calculate importance ratings. Assign a weighting factor to the relationships
(5-3-1). Multiply the customer importance
rating by the improvement factor (if any), the sales point factor (if
any) and the relationship factor in each cell of the relationship matrix and add
the resulting products in each column.
- Identify a difficulty rating (1 to 5 point scale, five being very
difficult and risky) for each subsystem / subassembly / part
requirement or technical characteristic. Consider technology maturity, personnel
technical qualifications, business risk, manufacturing capability, supplier
capability, and schedule. Develop a composite rating or
breakdown into individual assessments by category. Determine if overall
risk is acceptable and if individual risks based on target
or specification values are acceptable. Adjust
target or specification values accordingly.
- Analyze the matrix and finalize the subsystem/subassembly/part deployment matrix.
Determine required actions and areas of focus.
- Finalize target values. Consider interactions,
importance ratings and difficulty ratings.